Case Studies

A Collection of the Odd, Unusual and Interesting Found While Servicing Our Client Vehicles.

Originally intended as a showcase for customers of our workshop and staff’s abilities, this page has evolved in an interesting and informative teaching tool, and one of the most popular pages on our site!

By nature, these are rather extreme examples of failures, and not what we typically find during service. Our goal at Atlantic Motorcar is to prevent these from happening to you and your car. But rest assured, if we can fix these challenges, regular maintenance is breeze!

We like to call this our “YES WE CAN!” page. You can also view many of these concerns on our Facebook page. Each photo can be enlarged by clicking on it.

Secondary Air Injection Pumps, Kombi Valves and Check Engine Lights – Audi, BMW, VW, Mercedes and Volvo

Case Studies

What Is Secondary Air Injection System?
Secondary air injection (commonly known as air injection) is a vehicle emissions control strategy, wherein fresh air is injected into the exhaust stream to allow for a fuller secondary combustion of exhaust gases.

The Secondary Air Injection (SAI) system consists of three main parts, a pump, a valve and a solenoid, controlled by the engine computer.

The Secondary Air Injection (SAI) pump that creates positive pressure which is routed to a combination valve, or “Kombi Valve“. The SAI pump design is a vane pump turned by an electric motor. The pump’s air intake is filtered by a rotating screen or the vehicle air filter to exclude dirt particles large enough to damage the system. Air is delivered under light pressure to the injection point. A check valve prevents exhaust forcing its way back through the air injection system, which would damage the pump and other components.

The Kombi valve, as it’s called at times, is a pneumatically actuated shut-off valve that is integrated into the valve housing and allows the Secondary Air Injection (SAI) pump to add air to the exhaust gasses during start up and open loop to help with emission control. The early valves are vacuumed switched, while the later valves are electrically operated.

Finally a switching solenoid that routes engine vacuum when commanded to do so by the engine computer, to open the Kombi valve and allow air to flow into the catalytic convertor.

Operation
When the vehicle is cold, the engine computer commands on the SAI system motor to turn on, and create positive pressure. This pressurized air is then routed to the Kombi valve, directing the air into to the catalytic convertor. The computer also controls the Kombi valve, via engine vacuum and an electronic solenoid, to open and allow the air to flow into the catalytic convertor. This added pressurized air causes the convertor come on line quicker, clean up emissions, and prevent clogging of the expensive catalytic convertor.

The active secondary air system usually consists of an electric pump (see figure), the control relay, a pneumatic control valve, and a combination valve. The system is controlled by the engine control unit. While the system is working, the electric pump is switched on by the engine control unit via the control relay. The pneumatic control valve is actuated at the same time. The valve opens and the vacuum from the intake pipe operates the combination valve.

The vacuum causes the combination valve to open and the additional air conveyed by the pump is pumped into the exhaust pipe behind the exhaust valves. As soon as the lambda control becomes active, the secondary air system is deactivated. The engine control unit deactivates the electric pump and the pneumatic control valve. The combination valve is also closed, preventing hot exhaust emissions from reaching the electric pump and damaging it.

This design has been refined over the years, as emission control strategies grew more sophisticated and effective, the amount of unburned and partially burned fuel in the exhaust stream shrank, and particularly when the catalytic converter was introduced, the function of secondary air injection shifted. Rather than being a primary emission control device, the secondary air injection system was adapted to support the efficient function of the catalytic converter.

The original air injection point became known as the upstream injection point. When the catalytic converter is cold, air injected at the upstream point burns with the deliberately rich exhaust so as to bring the catalyst up to operating temperature quickly. Once the catalyst is warm, air is injected to the downstream location — the catalytic converter itself — to assist with catalysis of unburned hydrocarbons.

Failure Points
Increased emission values during the cold start and warm-up phases can be caused by a lack of post-combustion. The catalytic converter only reaches its operating temperature at a later point. Secondary air systems which are monitored by the engine control unit’s self-diagnosis function, cause the engine indicator lamp to illuminate in the event of fault.

The combination valve, or “Kombi Valve” as it’s called at times, is a pneumatically actuated shut-off valve that is integrated into the valve housing and allows the Secondary Air Injection (SAI) pump to add air to the exhaust gasses during start up and open loop to help with emission control. It serves as a one way check valve to allow the air from the SAI to flow, and prevent exhaust gases from entering and damaging the SAI pump.

A common failure is the Kombi valve, and If you are getting a fault code for secondary air injection system, it could very well be the Kombi valve that’s the problem. When these go bad, it can lead to malfunction in your SAI pump. Because these valves live in the exhaust system, they often can get carboned up over over time and when they do, they allow hot exhaust gases to enter the pump, condense into water, often filling and damaging the electronics on the SAI pump. As such a failed Kombi valve should be replaced right away to prevent damage the expensive SAI pump.

Not An EGR Valve
The Kombi valve is not EGR (exhaust gas recirculation) valve, both are one way check valves, but unlike the Kombi valve, the EGR valve recirculates unburnt exhaust fumes back into the combustion chambers (cylinders) to increase the quality of emissions.

An Ounce Of Prevention
If you’re an Atlantic Motorcar client, we’re going to be keeping an eye on this for you.
If you’re not, make sure it gets checked, kind of like that old bromide about voting, “early and often”. 😉

Our Goal For You and Your Car
Our goal is to save you money, not spend it. This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit. Our goal is to let you know about the small problems before they become big ones. Right now, we have a number of customer cars with well over 200,000 miles, and several approaching 300,000! And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.
Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969.

Thanks! 

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Be DEFinite About Your Mercedes, Land Rover, Audi, VW, Porsche and BMW Diesel DEF Fluid

Case Studies

Be DEFinite About Your Mercedes, Land Rover, Audi and BMW Diesel DEF Fluid

DEF (Diesel Exhaust Fluid) – The Other Engine Fluid
Along with oil, antifreeze, transmission fluid, brake fluid, and fuel, modern diesel engines also need DEF to run properly. All North American Mercedes Sprinters built after 2010 have DEF tanks, same with Audi, BMW, Land Rover, Porsche and VW.

DEF helps with emissions control and the computer in your vehicle will stop you from driving if it detects an empty DEF tank. But don’t panic if the DEF light on your dash comes on. You’ve got plenty of time to fill up.

So, what is DEF, why does your engine need it, and what’s the best way to fill the DEF tank?

What is DEF?
Diesel Exhaust Fluid (DEF) is a mixture of urea and water. Basically the same ingredients as urine. But don’t try peeing into the DEF tank to refill it – DEF is a specific proportion (32.5% urea, 67.5% water) and pretty pure. The impurities in your pee would mess up the SCR catalyst. Also, be sure the DEF fluid you select is compatible with your vehicle,

Urea is nasty stuff – it’s corrosive and will eat through copper cables. In the exhaust system, its job is to convert nitrogen oxides (NOx) into water and nitrogen. The DEF is injected into the exhaust pipe just before the selective catalytic converter (SCR system). The exhaust has already been treated several different ways by this point. The DEF breaks down into ammonia in the hot exhaust gasses. The SCR helps this ammonia to react with nitrogen oxides. This reaction produces water vapor and nitrogen – neither of which cause pollution issues.

The DEF Dash Light/Display
How much DEF you use will depend on your driving style, but it’s only a tiny proportion of the amount of diesel you use.
Some 2016+ vehicles have a DEF level indicator in the dash display (if you have the high line display with the steering wheel buttons). Everyone else pretty much as to guess how full their DEF tank is, or just wait for the dash display to light up.

When there’s 1.5 gallons of DEF left, the vehicle will warn you to refill.

DEF dash light
DEF dash light – display will also say “DEF Check”

If you have the high line LCD display, it will tell you to “Check Additive” (not a useful message) or “Check Diesel Exhaust Fluid” on newer vehicles. Ignoring the warning isn’t a good idea. When the DEF level gets to 0.8 gallons, the check engine light will also come on, and the van will tell you that you only have a certain number of starts left. After that, it will go into limp home mode and you won’t be able to drive at speeds above 5 miles per hour.

The sensor in the DEF tank seems to still be an engineering work-in-progress. It’s not uncommon to hear reports that it has failed, even though they’ve filled the tank up, part of this is due to the corrosive nature of the DEF fluid itself. The NOx sensor in the exhaust system also fails occasionally, and that can lead to DEF warnings too. The dash light won’t go out as soon as you add more DEF. It will take a couple of starts for the van’s computer and sensors to update.

What Does “Poor DEF Quality” Mean?
The dreaded warning messages, they always lead to the same thing, lost revenue and unexpected expenditures. So, you are driving, and you receive a message on the dash reading “Poor DEF Quality.” What does this mean? What should you do about it, or not do? By the end of this post, our hope is that you will have a clear understanding as to what this message is suggesting and how you can go about getting yourself back up and cranking out the miles as efficiently as possible  “Poor DEF Quality”…may not always mean your DEF quality is bad.

To start, “Poor DEF Quality” is highly suggestive and worded in a way that can be misleading. I believe the best way to word this message would be “High NOx Emissions Detected” or “Poor SCR Efficiency” (some mfg use this terminology). Either of these would be a more accurate representation of what is wrong and better encompasses its potential causes. In short, this message means that the NOx emissions measured at the outlet NOx sensor are higher than the computer expects for a given situation.

What can cause this message to come up?   The potential causes are a more extensive list than the dashboard message suggests.
While it is common that the root cause is poor DEF quality, it is not a guaranteed cause by any means.

Potential causes beyond bad DEF fluid include: 

• Bad NOx sensors
• Contaminated SCR box
• DEF dosing issues

• Potential EGR issue

Methods of Testing DEF
Technicians can use various methods to test DEF quality, such as a refractometer where you take a sample of the DEF, place it on the sight glass, close the lid, and hold it up to the light. Ideally, you expect to be at a level of 32.5%. Investing in a refractometer can pay great dividends if it can prevent even one roadside breakdown caused by an engine derate.

Another test option is putting test strips in the DEF tank. Test strips are the most cost-effective and easiest test solution for technicians. If the strip stays the same color, DEF is in good shape. However, it is crucial to know exactly when to test the DEF.

When to Test DEF
There are a few indicators that a technician should test DEF quality, including:

  • Fault code(s) indicate poor DEF quality. An engine light will typically appear, and technicians should test DEF and perform a comprehensive diagnosis of the aftertreatment system.
  • A vehicle sat for an extended period of time. If your fleet has a truck experiencing longer downtime, you may want to test DEF before dispatching the vehicle as DEF can reach temps over 160 degrees, shortening the lifespan.
  • DEF has a noticeable odor. Typically, DEF may have a slight ammonia or sulfur smell, but a noticeable, pungent scent could indicate poor quality. When testing, technicians should smell the DEF tank to ensure there isn’t cross-contamination.

Overall, the interval for testing DEF quality will depend on factors such as the vehicle’s usage, operating conditions, and manufacturer recommendations. Technicians shouldn’t wait for other signs that the DEF has gone bad.

Diagnostics At Your Fingertips
Diagnosing through the list can be tough if you have nothing else to work with. But if you have any recent trouble codes, they could give you some direction as to the best place to start your diagnosis.

If this message arrived shortly after a DEF fluid refill, the easiest thing you can do is to test your DEF fluid. Is it good? If it is good, what should you do next?

The next thing to do is a thorough visual inspection. Look over the entire exhaust and DEF systems, including the EGR all the way through to the SCR. Any visible leaks, excessive corrosion, or unusual wear typically suggests a problem area.

If your truck has not received all its factory recommended maintenance, a thorough diesel tune-up would make sense. A new DEF filter, EGR tune-up, and a fresh set of NOx sensors can go a long way. It can eliminate the potential of skewed sensor readings or poor EGR performance, and it can assure you that you’ll have the correct information feeding the computer for future diagnosis if the problem continues.

After a diesel tune-up, a recent code history could help if you had some recent issues, but no items replaced, it may be the root of your headaches. For example, if you had a DEF pump code recently, it might make sense to diagnose the DEF injection system. Beyond that, you will want to start digging into the individual components and testing each one.

While there is no way to eliminate all the potential issues, maintenance does wonder in the prevention of unexpected problems. During the diagnosis process, we use a very sophisticated diagnostic computer be used to put our vehicle into a forced DPF regeneration, which is often a part of diagnosing aftertreatment issues.

An Ounce Of Prevention
If you’re an Atlantic Motorcar client, we’re going to be keeping an eye on this for you.
If you’re not, make sure it gets checked, kind of like that old bromide about voting, “early and often”. 😉

Our Goal For You and Your Car
Our goal is to save you money, not spend it. This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit. Our goal is to let you know about the small problems before they become big ones. Right now, we have a number of customer cars with well over 200,000 miles, and several approaching 300,000! And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.
Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969.

Thanks! 

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Porsche 911 / 996 Coolant / Water Pump Failure and Correction

Case Studies
Atlantic Motorcar Shop – Porsche 996 – Coolant Leak, Water Pump Bearing Failure

No, that’s not a green icicle in the photo; rather, it’s a small stream of coolant coming from this Porsche engine.

Tech Findings

One of our AMC Service team members, Dylan, found and documented this interesting failure yesterday. Although it is on a Porsche, it is pretty instructive to what a water/coolant failure looks like in almost any car.

Signs and Symptoms

Fortunately, the client wisely shut down the car and had it towed in before any engine damage occurred. A rather catastrophic support-bearing failure of the engine coolant pump impeller at 50K miles, occurred without warning.

Failure Mode

If you follow the photo, you can see where the pump pulley has worn through the left side of the pump case, cutting a nice curved slot for about 3 inches. The failed bearing allowed the pump pulley to cock out of alignment, and the drive belt tension pushed it against the aluminum base, cutting a grove right through and creating a substantial coolant leak.

Causes
One always wants to determine the cause of any failure; parts do wear out by nature of mechanical systems, but something that should not fail, or fails catastrophically, deserves a second look with an eye to prevention. On the engine coolant pumps on most engines, the pump impeller shaft is supported by a sealed roller bearing.

This bearing is lubricated for the life of the pump, but over time, the rubber seal that separates the bearing from the engine coolant can start to leak, allowing coolant to seep into the bearing, washing out the lubrication, and causing scoring and corrosion. The bearing eventually fails like this one, and often the bearing failure is the first sign of the pump problem unless coolant comes out of the water pump seal or weep hole.

In this case, there was little that could have been done to prevent the problem, or even diagnose it early, as no external coolant leakage was present. You’ll usually note coolant seepage at fitting, hoses, and pumps, by the build-up of a crusty substance around the source of the leak; this is a solid red flag. But in cases like this, there is little, other than proactively replacement of the pump, that could have been done.

Correction
Being a rear-mounted engine, with the engine radiator conventionally mounted in the front of the car, the 911 series has some very long coolant pipes and hoses; (see the diagram), all of which should be inspected during this service. Also, because of the length of the cooling system pipes and hoses, is very important that a proper and thorough bleeding procedure is done to remove any and all air from the system. Ideally, a vacuum bleeding machine should be used for service and filling of the system.

Correction will be the removal of the failed pump, and cleaning the engine and coolant system passages from any metal filings. Replacement of the coolant pump, replacement of the thermostat (right in the same area), replacement of the drive belt (soaked with coolant), then flush, fill, and bleed the air from the cooling system.

An Ounce Of Prevention
If you’re an Atlantic Motorcar client, we’re going to be keeping an eye on this for you.
If you’re not, make sure it gets checked, kind of like that old bromide about voting, “early and often”. 😉

Our Goal For You and Your Car
Our goal is to save you money, not spend it. This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit. Our goal is to let you know about the small problems before they become big ones. Right now, we have a number of customer cars with well over 200,000 miles, and several approaching 300,000! And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.
Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969.

Thanks! 

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Automotive Air Conditioning Service – Myths, Magic and Mistakes

Case Studies

A Little Background
Air conditioning is one of those systems that has evolved over the years, and with it some old myths that have died hard. The days of the R12 (Freon) systems are nearly 30 years in the past, but I still here from time to time, the same myths and mistakes, chief among those is the “topping off” concept. This can be downright dangerous, if you buy the the flammable gas that is often sold in small quantities rather than the proper refrigerant.

The other thing I hear about is A/C  compressor failures, with no explainable cause. There are two general types of compressor failures, the first being electrical, which is a small subset, and other being mechanical. Almost every compressor failure occurs as a result of mechanical wear or damage, and almost always it relates to a lubrication failure caused by undercharging, or systems run low on refrigerant.

An Ounce of Prevention
I’ve authored this simple case study to explain how A/C has evolved from the “early days”, and the importance of thinking of preventive maintenance on the A/C system to prevent premature failures. We often think of A/C as system requiring no maintenance until it doesn’t work. That’s akin to ignoring brushing your teeth until you get a toothache, by then it’s often too late. You read how some small loss of refrigerant from a sealed A/C system is not only normal, but should be expected.

Myth 1 – “Topping Up” A/C Systems
The very first myth that needs to be addressed is “topping up” your system. Did you know that if your system is 10% low, you will lose 40% of your oiling capability to your A/C Compressor? You won’t experience lack of cooling until you have lost 40% of your refrigerant. During that time, from -10% to -40% loss of charge, you are doing damage to your compressor.

Problem is, your compressor does not have a sump like your engine does, it relies on the proper volume of refrigerant in the system to push the refrigerant oil back to the compressor. The compressor is one of the most costly parts in your vehicle’s climate control system, so therefore preventing problems should be the focus. The number one reason for compressor problems is caused by lubrication failures, most often the lack of refrigerant to move the oil around the system, in other words, an undercharged or leaking system.

Mistake – Why “Topping Up” Really Doesn’t Work
The problem with topping up your system is you don’t know how much refrigerant is in your system to add to it. There is no “dip stick” to indicate refrigerant charge. Back in the “old days“, vehicles had what were termed “sight glasses“, a small clear viewing port, often on the receiver dryer, that allowed one to see into the system, and to charge until no air bubbles were present. The sight glass went the way of the old R12 refrigerent systems, back in 1994.

Yet the myth persists, nearly 30 years later, that one can just “top off” the A/C system, like you top off brake fluid. Problem is, brake fluid is in a translucent container, refrigerant is not, you can’t see through the metal pipes and lines. When you add refrigerant to your system that is blowing warm you can increase the charge until the system starts to blow cold, but you may still be in the -10% to -40% low refrigerant range, which is still doing damage to your compressor by not providing proper lubrication to the system.

The Right Way
The only proper way to service your vehicle air conditioning is to recover the system, pull a vacuum to remove contaminants such as air and moisture, install refrigerant oil to lubricate the compressor, and then install the factory refrigerant charge as specified by the manufacturer. This requires a professional A/C service machine, which costs several thousand dollars, and some specialized equipment. The good news is that most A/C recharge services cost under $300, far less than a compressor replacement.

Little Cans Make A Big Difference

  • The current automotive refrigerant (R-134a) is a highly potent greenhouse gas.

  • Just the gas contained in one single 12-ounce container is equivalent to the carbon dioxide (CO2) emissions from burning 150 gallons of gasoline!

  • The gas from two 12-ounce containers, if released into the atmosphere, will cause the same global warming pollution as driving all the way across the country diagonally, from Los Angeles to New York.

Myth 2 – “Magic” Parts Store Recharge Cans – Buying Yourself A Can Of Trouble
The second myth is those “little cans of refrigerant” that are being sold at do it yourself parts stores. Federal Law states you can not sell refrigerant in containers that contain less than 22 pounds (10kg). If you are purchasing a container that has 6-12 ounces of “refrigerant” in it, this is often NOT R134a (refrigerant) which is required for your vehicle. What you are buying is called a Hydrocarbon, also known as a propane and butane mixture.

The way you can tell is to look at the labeling on the container, it will show the explosive and flammable symbol. R134a will ONLY show the compressed gas symbol on the label. R134a is not flammable or explosive, and is specified by the vehicle manufacturer for your vehicle. R134a and all proper refrigerants require technicians to be Federally certified to handle them. They are not available to be purchased without the proper certification.


A/C Fact – It’s Always Working – Even In The Winter

Here’s a surprising fact, your vehicle’s A/C never takes a break, not even in the winter. In fact your vehicles air conditioning system runs whenever you turn on the Defrost mode, and often runs when in the automatic mode.

The climate control system uses the a/c as it is designed to engage and act as a dehumidifier to remove the moisture from the air entering your vehicle to aid in removing moisture (fogging) from your windows.

You will notice vehicles with working air conditioning that the side and back windows are always clear. Vehicles without air conditioning or needing A/C repairs will have steamed up side and back windows which continually need wiping to clear.

Waiting Costs You Money
If your A/C system is not working 100% at the end of the summer season and you think you will get it fixed next year, do not put it off or you will do damage to your compressor. Remember, when you turn on the Defrost Mode, the compressor is engaged. With a low refrigerant charge over the winter months, you’re not getting the refrigerant oil back to the compressor which is damaging it all winter season that will lead to costly repairs in the spring time.

A/C Fact – A/C Service Is Normal – Think Every 3-5 Years
The Society of Automotive Engineers (SAE) designed the A/C fittings that are on your vehicle. These fittings have a SAE acceptable leakage rate of 1/4 ounce of refrigerant per year per fitting. That does not sound like a lot, but the average vehicle has 8 fittings. This means that you are losing 2 ounces of refrigerant per year.

So now that we know that you are are losing 2 ounces of refrigerant per year, and A/C service is just part of a proper maintenance schedule. It is recommended that you service your air conditioning every 3-5 years. This will ensure that your compressor is never “starving” for oil. The older vehicles used to have systems that held upwards of 36 ounces of refrigerant. Today’s vehicles have much smaller systems that require as little as 15 ounces of refrigerant. The need to service your air conditioning has become much more important with these reduced capacities or system damage will occur.

Our Goal For You and Your Car
Our goal is to save you money, not spend it.
This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit.

We aim to let you know about the small problems before they become big.
Right now we have a number of customer cars with well over 200,000 miles, and several approaching 300,000!
And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.

Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969!

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The Proper Use Of The Air Conditioning Air Recirculation Button In Your Vehicle

Case Studies

The Proper Use Of The Air Recirculation Button In Your Vehicle
When the weather heats up, and it’s time to turn on your vehicle air-conditioning, there’s one button you may not know how to use. Have you seen the button in your car that shows an arrow going in a circle? That’s the air-recirculation button. Although some drivers know what it’s called, many don’t know what it’s for! If you’ve ever wondered why it’s there and what it does – read on; you’ll be glad you did!

What Does The Air Recirculation Button Do?
The air recirculation button effectively cuts off the outside air to the inside of the car, ‘recirculating’ air inside your vehicle.
What the air-recirculation button is used for:

  • Boosting your AC to help your cabin get as cold as possible as quickly as possible
  • Stopping pollution & exhaust fumes i.e., in a city center traffic jam, entering your cabin
  • Reducing pollen when driving if you suffer from hayfever
  • Stopping strong outdoor odors entering your car

The Benefits Of The Air Recirculation Button

  • The air-recirculation function ensures your AC works to the optimum level, allowing your vehicle to get as cold as possible as quickly as possible.
  • It helps stop pollution, smells, and pollen from entering your cabin
  • It helps keep your air-filter cleaner for longer
  • It reduces strain on your AC system
  • It helps reduce fuel consumption by assisting the AC system

Some new cars do not have an air-recirculation button. This is because modern vehicles are often equipped with sensors that monitor the cabin air and moisture levels, adjusting the “air circulation” automatically.

When To Use The Air Recirculation Button

  • When using AC, unless the system becomes too cold, use it to quickly cool down your vehicle
  • In summer & hot weather
  • In dense traffic, to stop pollution from entering the cabin

Extreme Weather
If you’re driving in a heatwave, you should turn on your AC & your air-recirculation ON to ensure your air-con gets as cold as possible as quickly as possible.

If you don’t switch the air-recirculation button on, your air-conditioning will constantly cool warm air from outside your vehicle, and will have to work much harder, putting more stress on the blower & air compressor.

The system works by recirculating the cool air you get from your A/C when you first turn it on. The longer it’s on, the cooler your vehicle will get! If you don’t use it, the car will use the air from the outside that is much warmer, and your A/C will work harder and continuously to cool the hot air.

If your AC has to work harder, you’ll increase fuel consumption, and your cabin won’t reach its optimum level of coldness from the air-con system. You will also be putting undue wear and tear on your A/C compressor.

When Not To Use Air-Recirculation
In winter and cold weather. Generally, when its cold outside, ensure the recirculation button is switched off! The air-recirculation button is best to use alongside your AC during warm weather. It doesn’t benefit much during cooler weather and can even be detrimental.

Some drivers think it makes sense not to have “all that cold air coming in” if they use heaters in winter. However, in reality, it’s best to keep it switched off. The standard “fresh air” mode forces the outside air through your heater core, so it’s nice and toasty before it reaches you, and your windows will de-fog a lot quicker and stay that way while you drive.

Disadvantages Of The Air Recirculation Button
The main downside of the air-recirculation button is that it traps humidity inside the car, which results in misted windscreens, especially when the air is cold outside and in wet weather.

  • It can cause your windscreen to mist up
  • It can trap humidity in the cabin
  • If your vehicle is fully loaded with passengers, it can cause it to be stuffy and may make you drowsy

Our Goal For You and Your Car
Our goal is to save you money, not spend it.
This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit.

We aim to let you know about the small problems before they become big.
Right now we have a number of customer cars with well over 200,000 miles, and several approaching 300,000!
And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.

Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969!

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Porsche Panamera – Water Leaks and Clogged Drains – Electrical Issues – Prevention

Case Studies

A Tip From A Friend and Colleague
From our friend Tony Callas, at Callas Porsche Service in California, is this service tip for Panamera owners. Photos are Tony’s, but here at Atlantic Motorcar, we’ve all seen this happen before, esp in the Boxster series. Especially so for cars that are kept outside or frequently washed.

Tony’s Note – ATTENTION PANAMERA OWNERS:
Please clean out your rear hatch water drains. If these two drains get clogged, water will fill up the rear hatch and then leak water into the battery (electronics) area, which will cause all sorts of havoc and get super costly!

AMC – A Word About Water Drains On Cars
Drains aren’t just for bathtubs or the kitchen sink; they also exist in your car to drain away from the effects of rain, ice, and snow. Yet, they’re one of the most neglected of service items. Often considered only when it’s too late.

The Problem
If your car has persistent condensation in colder weather and damp mildew smell, chances are that the foam pads in the footwells and on the floor behind the seats are saturated with water. A cursory check will confirm this for you: have a feel around the join of the floor carpet and rear carpet behind the seats – press down on the floor carpet, and be sure to check the trunk (if your Porsche is equipped with one. If you see, feel or hear water squelching, then you’re carrying water down there.

There is no quick fix to this one: forget about gel pads, hairdryers, heaters, etc. The seats have to come out, various bits of the trim removed, the carpet lifted. You will see 2 thick foam pads attached to the carpet, as highlighted in red in the picture. The pads sit in “sumps” that do not drain anywhere – how clever is that?! Once the foam pads are exposed, that will allow you to squeeze out as much water as possible and then use whatever other means to dry out the pads. The flimsy rear drain trays need to be inspected for any holes that might allow water entry. And we generally run a small dehumidifier inside the car for 2-5 days to thoroughly dry it all out.

That’s just the start, for you now must check the control modules, and there are numerous ones, wiring harnesses, and electrical connectors for the deleterious effects of water entry. Modules really need to be opened up and circuit boards exposed, wiring needs to be checked for insulation integrity, and the small, often very small, electrical connectors checked for any signs of corrosion.

An Ounce Of Prevention
Check, or have checked regularly your vehicle’s cowl, sunroof, and other body drains. This is doubly true if the car lives outdoors, rather than in a garage. You’d be amazed at how quickly the “schmutz” builds up in the drains and lines. Pine needles, leaves, road dirt, pollen, you name it. Cars that live outside should have drains checked, and cleaned as necessary, ideally every quarter. As my mother used to tell me, “An ounce of prevention is worth it pound of cure.”

If you’re an Atlantic Motorcar customer, we’re going to be keeping an eye on this for you (Doesn’t hurt to remind us if you’ve noted any water inside your car, odd, musty smells, etc.). If you’re not, make sure it gets done, kind of like that old bromide about voting, “early and often”. 😉

Our Goal For You and Your Car
Our goal is to save you money, not spend it. This is why each and every car that we service gets a free Courtesy Maintenance Inspection during its first visit. Our goal is to let you know about the small problems before they become big ones. Right now we have a number of customer cars with well over 200,000 miles, and several approaching 300,000! And these cars are not just limping along – most look and drive pretty much the way they came out of the showroom.

Proper maintenance is an investment in the life of your vehicle.
Knowing, not just doing, but actually knowing and understanding the difference, makes all the difference.
Be sure your car is properly loved, our professionals will attend to both you and your car’s needs.
Atlantic Motorcar…Extraordinary Service for Extraordinary Cars, just a phone call away, (207) 882-9969.

Thanks! 

 

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Keeping Your Cool – Air Conditioning (A/C) Recharge System Service Process and Costs

Case Studies

Anticipated Service Cost
If your car’s AC system efficiently drops and is no longer cooling or cooling effectively or has a flashing warning light, it may be running low on refrigerant. Pending finding no gross leaks, it may be as simple as a recharge. This isn’t a costly repair and likely won’t need to be done before you hit the 60,000 to 100,000-mile mark, so any car for five years or older will likely need this done at least once.

For most cars, an AC recharge will cost between $200 to $300, depending on the amount of refrigerant needed (larger vehicles use more refrigerant), including the addition of UV leak detection dye. It’s a straightforward procedure, but it can take a while to check everything out and ensure no further damage.

When to Get an AC Recharge Done?
It’s important to have your AC system recharged, don’t neglect an inoperative system. You can run it for a very short while before there is any serious damage, but you should take care of this problem sooner rather than later. Over time, the lack of refrigerant will put extra pressure on the compressor and other parts of the AC system, making them work harder; plus, any moisture which has entered the system can cause them to break down and require extensive repairs and replacement.

The best way to know if your system needs a recharge is to pay attention to its operation. You may notice that your system isn’t working as well as it should. It may have trouble producing cold air or make weird noises or overheat. These are signs that you need to have some inspection or service needs to be done.

What Is A Recharge System Service
Your AC system runs on a refrigerant. The refrigerant removes moisture from the inside of the car and deposits it to the outside. So you feel comfortable. But over time, the refrigerant will run out. It can escape through normal seepage. Also, major leaks or component failures can deprive the refrigerant. Once the refrigerant is low, the AC will no longer function properly.

Without the right refrigerant levels, your system can overheat and experience pressure that can damage the other components of the AC system. An AC recharge means checking the current pressure levels in the system and recharging it to get it to where it needs to be. This allows everything to operate smoothly, last longer, and produce cooler air.

What Is Done During AC Recharge Service
The technician will want to check for the source of the problem first. If you have a concern about some issue with your AC, we will perform a thorough check of the system to ensure that by recharging your unit, we are taking care of all the problems. You don’t want to pay for a recharge and then find out later that you have a refrigerant leak!

Once the technician sees that the system needs a recharge, he will evacuate all the refrigerant from the system using a coolant recovery machine. Once the parts have been evacuated, he will replace them and remove all the air from the system. The new refrigerant will be installed, and any damaged or worn seals must be replaced. If the unit leaks, one or more seals or hoses are usually at fault. We use a UV Dye test to check for current and future leaks.

UV Leak Detection
As many refrigerant leaks are often not detected until the vehicle has been in service for some time, we have chosen the UV Dye method as the most accurate and cost-effective available.

There are three common ways of finding leaks in the system:
1. Visual. If the leak is very obvious, we will see it with no help.
2. Use of a special UV flashlight and goggles
3. Gas/Refrigerant Leak detector.

This can only be done if the system has enough refrigerant & oil/dye in it to detect a leak, which is why this service must be performed first to determine the source of failure. This test will help us find the largest leak, it is possible that other (smaller) leaks will show up after a larger leak is repaired.

The customer must return at the first sign of loss of cold air; if the system runs out again and rain washes the dye away, this process must be re-done at the customer’s expense. Refrigerant is a greenhouse gas, and it is illegal to vent it out into the atmosphere. Therefore, we are not allowed to knowingly recharge a leaking A/C system.

Benefits of AC Repair
By recharging your AC unit, you will enjoy a system that works more efficiently and lasts longer. The air it produces will be colder, and you will protect the rest of your AC system and the surrounding car parts from overheating and other types of damage. You also enjoy the benefits of an AC system that works like it should every time, providing cold air when needed and keeping your car comfortable.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue and others; with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Finally
Questions or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, don’t hesitate to get in touch with us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.
Thanks!

Warmly,
The Atlantic Motorcar Center Service Team

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Audi, Porsche and VW 2.0 TSI Engines – Rear Main Seal Oil Leaks And Proper Correction

Case Studies

Vehicles Affected
The Audi and VW 2.0L TFSI, TSI, and FSI engines have been around for almost 15 years. During that time, Audi/VW made endless revisions and updates to the hardware and software.

You may have read of the problems with the leaking rear main crankshaft seal on the Audi and VW 2.0 TSI engines. This is a common pattern failure with 2009-2012 Volkswagen Tiguans. We say 2009-2012 VW Tiguans, but the issue can occur on any 2.0TSI Volkswagen, Audi or Porsche (2014+ Macan) using this seal design.

As with all cars, the Rear Main Seal is located between the engine’s crankshaft and the flywheel, which means the transmission must be removed to replace this part. This is a considerable labor operation, so it’s critical to use only the highest quality parts, and fully service the system to prevent repeat failures.

This often first evidenced by a leak of oil under the car, which may be found during a service visit, and later will show up on the ground. The leak can range from a couple drops on the driveway to a pool. In extreme cases, the MIL (Check Engine Light) will illuminate due to a vacuum leak out the seal, as the engine will be running lean, more about that below.

Symptoms and Diagnostics
When the rear main engine seal fails, you will find an oil leak coming from the bottom of the vehicle where the engine and transmission meet.  Ensure the leak is not coming from higher up on the engine before deciding the main seal is bad, cam cover gaskets and front timing covers leaks must be handled first. Cleaning the oil from the engine, and the use of an oil based UV Dye Leak Tracer is a good method for confirm the diagnosis.

As the engine uses a sealed crankcase system, you also may experience fault codes like P0171 – System too lean, or misfire fault codes P0300, P0301, P0302, P0303, and/or P0304.  It is essential to note that these fault codes should only be considered as potentially related to a bad rear main seal if you are experiencing an oil leak from the area between the engine and transmission where the rear main seal is located and absent an oil leak are NOT a diagnostic indicator for rear main seal replacement.

Causes
Rear engine main seal failures will often be caused by two things, the first, a failed Crankcase Vent Valve and PCV system which causes excessive crankcase pressure (PCV) issues, and the second, the seal design itself.

Crankcase Vent Valve
VW Technical Service Bulletin 2015505/1 discusses increased oil consumption and blue smoke. Upon inspection, oil can be found in the air intake hoses after the turbocharger, and the oil can be seen leaking from the oil filler cap.

The cause of the problem is that the guide pin (see yellow arrow) that is part of the check valve in the intake manifold side of the valve may break, preventing the check valve from correctly sealing when boost pressure is present in the intake manifold. Intake boost pressure will be applied to the engine crankcase, resulting in oil leaks and the prevention of engine oil from properly draining from the turbocharger through the oil return line.

In addition, infrequent oil changes, extended service intervals, or oil changes with the incorrect oil and filter can lead to a build-up of sludge in the engine, and clog or damage the Crankcase Vent Valve and PCV system. Once clogged, the effect of this is too much pressure building up in the crankcase, and the PCV isn’t venting it out correctly. When this occurs, over time, it causes the rear main seal to blow out and begin leaking.

We have also heard possibilities of this issue becoming prevalent due to using incorrect spec oil, but a failed Crankcase Vent Valve and PCV system in fact causes most failures. The part has been redesigned, and there is a superseded part number; always double-check with Audi/VW/Porsche electronic service information to ensure the latest and greatest part is installed.

The Seal Design
The other cause we mentioned is the main seal design itself. The OEM rear main seal utilizes a poorly designed PTFE “sealing lip” in an inexpensive stamp steel housing, which over time and with overpressure, can separate and lead to an oil leak between your engine and transmission.

In the past,  the seal was almost always housed in a rigid aluminum rather than stamped steel housing. There is an upgrade for some cars, using a conventional old-school, durable rubber seal, which we highly recommend.

Correction
Because of this issue with the PCV becoming so prevalent, VW has issued redesigned seals that resolve the issue at hand, but do not automatically fix or prevent a pre-existing failed or failing rear main seal.

It is important to note that if you have an issue with your rear main seal leaking on your VW or Audi 2.0T TSI engine, you should definitely replace your Crankcase Vent Valve and PCV system at the same time. Failing to do so may result in premature replacement rear main seal failure. Whenever we replace a rear main seal, we always quote replacing the PCV with the updated version (if it hasn’t been already), the rear main seal, and normally a full synthetic oil change with VW spec oil.

Upgrade
For some cars, a billet aluminum rear main seal kit is designed to replace the failure-prone stamped steel factory part. This billet aluminum rear main seal kit is CNC machined from 6061-T6 Aluminum and features an OEM Viton Elring seal with an integral tension spring to ensure a tight seal to the crankshaft. The OEM rear main seal utilizes a poorly designed PTFE “sealing lip” which, over time, leads to an oil leak between your engine and transmission.

This kit has been tested and proven to last under high heat and is an excellent upgrade for replacing your leaking rear main seal. It is also an outstanding preventative maintenance modification that can save you from future headaches of oil leaks, stained driveways, and reduced performance that a leaky OEM rear main seal brings with it.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue and others; with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Finally
Questions or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, don’t hesitate to get in touch with us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.
Thanks!

Warmly,
The Atlantic Motorcar Center Service Team

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Porsche 911, 912 and 914 – Steering Tie Rod Upgrade Kit – Conversion To Turbo Tie Rods

Case Studies

Background
First off, if you don’t know much about steering tie rods, the basic definition is that it connects the steering rack (in this case, a gear-driven box that translates turning the steering wheel into side-to-side motion to turn the front wheels known as a “rack and pinion”) to the wheel hub assembly (brakes, rotors, wheel, tire, etc.). It “ties” the track to the wheels.

The steering rack is up in the car’s underside, and the wheel hubs both turn and go up and down. So you need something that “ties” it together but can also handle all this movement. So it becomes a very fancy thing that needs two joints to be able to handle the movement. It could be a solid, straight bar if it didn’t have to move up and down and change the angle of motion. But it does. So we have two joints on it to do its job and manage the angles.

Original Porsche Design
On basically all Porsche 911, 912, and 914 models from 1969 through 1989, the tie rods look like the one shown below in the “Old vs New” photo. The exceptions may be cars already serviced and updated. The old tie rod has a normal ball joint at the wheel side (the “tie rod end”) like the new one. But at the other end, the old tie rod has an angled hinge-type joint with rubber bushings. On the outer end, which attaches to the wheel spindle, is the traditional tie-rod end with a ball and socket-type joint on the suspension upright end.

Why Update Needed
However, on the steering rack end, the inner tie rod is a strange-looking joint that houses a rubber bushing. Porsche designed this to help quell steering wheel vibration on their sports cars and installed this rubber bushing rather than the now traditional ball and socket type joint. Given the design and materials of the late 1960s, this rubber bushing was probably not too bad when it was brand new, but over time it wears down, and you lose a lot of steering feel and directness with this nasty old rubber. Again, every air-cooled Porsche used this tie rod style for two decades. That is, every air-cooled Porsche except one.

Then The Porche 930 Happened

It was in 1976, Porsche introduced the 911 Carrera Turbo (type 930) with a 3-liter engine and a turbocharger providing additional shove. It was a phenomenal car, a world-beating car even, an insanely fast car in its day. Because the Turbo was a bit of a handful to drive, Porsche wanted to make sure there was not any steering bind or even momentary delay in the response of the front wheels to the driver’s steering inputs. As a result, they removed the standard tie rod and replaced it with a metal-on-metal ball and socket-type joint at the steering rack.

Recommendation
Since then, Porsche enthusiasts have figured out that the two styles of tie rods are interchangeable and have installed several thousand sets of Turbo Tie Rods on non-turbo Porsches. Which is exactly what we do here. The kit shown below is the Porsche 930 kit, which we retrofit to the early 911s, 912, and 914 we care for.

Next Steps – Proper Alignment
After the tie rod update, a proper four-wheel tracking alignment must be carried out.
Our workshop uses the Mercedes Benz of alignment machines, the Hunter Hawkeye Elite, recommended by most of the major European auto manufacturers.
There are four key measures to each alignment: caster, camber, toe, and thrust angle, and we’ll explain those below.

Camber
This suspension angle shows how the tire angles away from 0 degrees vertical when viewed from either the front or rear of the vehicle. Expressed in degrees, negative camber means the top of the tire tilts toward the vehicle’s center, while positive camber means the top tilts away from the center. A visual cue for a camber problem is excessive tire wear on the inner or outermost ribs.

Caster
This angle shows the forward or backward slope of a line drawn through the upper and lower steering pivot points when viewed directly from the side of the vehicle. Also expressed in degrees, caster is measured by comparing a line running through the steering system’s upper and lower pivot points (usually the upper and lower ball joints of an A-arm or wishbone suspension design or the lower ball joint and the strut tower mount of a McPherson strut design) to a line drawn perpendicular to the ground. Caster is said to be positive if the line slopes toward the vehicle’s rear at the top, and negative if the line slopes toward the front. A visual cue for a caster problem is serious tire scrub laterally across the tread face.

Toe
Identifies the direction in which tires are pointed relative to the vehicle’s centerline when viewed from above. Toe can be expressed in either degrees or fractions of an inch. When looking down upon a vehicle, “toe-in” is when the leading edge of the tire is pointed toward the vehicle’s centerline. Conversely, “toe-out” refers to a tire face that points away from the vehicle centerline. The toe setting is typically used to help compensate for the suspension bushings’ compliance to enhance tire wear. Service Tip – The toe alignment also can be used to adjust vehicle handling; for vehicles that “wander,” the toe can be set slightly more toed in for directional stability. 

Thrust Angle
Consider an imaginary line drawn perpendicular to the rear axle’s centerline. This measure, expressed in degrees, compares the direction in which the rear axle is aimed at the vehicle’s centerline. The thrust angle also confirms if the rear axle is parallel to its front axle and that the wheelbase on both sides of the vehicle is the same. If the thrust angle is incorrect on a vehicle with a solid rear axle, it often requires a trip to the frame straightening shop to correctly reposition the rear axle.

Tech Note
There are various reasons for any of these alignment measures to be incorrect. At the same time, adjustment angles can be adjusted by a skilled technician to correct for inherent vehicle problems, correct for unusual tire wear, or to improve the performance and feel of a vehicle.

Alignment Specifications
All vehicle manufacturers have set specific alignment specifications for each vehicle. These are the “preferred” angles for camber, caster, and toe (with the preferred thrust angle always being 0 degrees). OEMs also provide the acceptable “minimum” and “maximum” angles for each specification and are usually within plus or minus one degree of the preferred angle.

Vehicles With Steering Angle Sensor
Sometimes, an additional labor operation must be performed to calibrate the steering angle sensor. The Steering Angle Sensor is what tells the onboard system if the steering wheel is pointing straight, left, or right and by how many degrees. Suppose the steering angle sensor data does not match with the rest of the vehicle data. In that case, the traction control system will likely trigger a plausibility error because the car doesn’t match what the steering angle sensor tells it. As mentioned, this is a separate labor operation from a standard four-wheel alignment and will be billed separately.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue and others; with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Finally
Questions or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.
Thanks!

Warmly,
The Atlantic Motorcar Center Service Team

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Bosch CIS (Continuous Injection System) or K-Jetronic Demystified

Case Studies

Background
So you bought a vintage Audi, BMW, Mercedes, Saab, Volvo or VW with the Bosch CIS fuel injection system. To which I say, “Cool” I cut my teeth on CIS as a young tech back in the 80s and 90s, and have a strong fondness for the system. The design is typically German, simple, reliable, and very ingenious.

Bosch CIS Is K-Jetronic
Bosch CIS (Continuous Injection System) or K-Jetronic, has earned an unfair reputation as being difficult to service as it is largely a hydraulic system relying on pressures and pressure differentials to function.

No Scan Tools
One can’t just plug into it with a scan tool and find answers; it requires understanding how the system operates to know normal and abnormal parameters. On the other hand, since it is largely a mechanical system, there are far fewer things to go wrong with it, and it is nearly bulletproof.

Theory Of Operation
The Bosch K-Jetronic (K-Jet) system comprises different components, which are discussed below, and their functions. Only the components related to the system are shown below. The K-Jet system belongs to the group of CIS injection systems, which stands for “Continuous Injection System.” This means that the fuel is continuously injected into the inlet manifold. The system is completely mechanical, relying on pressures and pressure differentials to function.

From the end of 1979, this system was modified by adding a lambda control system (oxygen sensor to create a closed-loop mixture control system. This new system was known KA-Jetronic, or K-Jet with Lambda. This system is shown in the figure below; the components 11, 12, 16, and 18 are specific to this lambda control system and are, therefore, not present in a mechanical K-Jet system.

From Cold Start
Let’s take it from a cold start. Cranking the starter triggers the cold start valve to spray into the intake plenum on early models. Due to flooding problems, a thermo-time sensor was added to prevent the cold start valve from spraying fuel for more than 8 seconds and when the engine temp is warm.

The control plunger inside the fuel distributor moves according to how much air deflects the air sensor plate and is also affected by control pressure. Control pressure acts on the top of the control pin; cold control pressure is low, about 1 bar (15 psi), depending on the model, which lessens the resistance of the air sensor plate to rise. As the engine temp comes up, the control pressure rises, and the resistance increases leaning out the mixture (hot control pressure is about 3 to 3.5 bar (50 psi).

The internals of the fuel distributor determines how much fuel is output to the injectors. There are two chambers separated by a stainless steel diaphragm; the lower chamber is system pressure set by a small spring and is adjustable but almost never necessary. When the control plunger rises, this allows system pressure into the upper chamber; once the pressures in both chambers are equal, the spring pressure deflects the diaphragm and let’s fuel out to the injectors. Note the diagram below.

So let’s look at each component of a typically K-Jet system.

1 – Fuel Tank
Unfourtantly its greatest enemy is water, which wreaks havoc on the small metering passages in the fuel distributors and filter screens in injectors and ports.

2 – Fuel Pump
The fuel pump is used to supply the system with the necessary fuel pressure. A non-return valve is installed just after the fuel pump, which is needed to keep the system pressurized after the engine has been switched off; this allows for easy warm starts. The design is an electrical roller type with a check valve to prevent backflow and a relief valve in case of restriction.
system pressure = 80 psi or 5.5 bar (14.7 psi  = 1 bar)

3 – Fuel Acculator 
The fuel accumulator has two functions:
– After the engine is switched off, this accumulator keeps the fuel system under pressure to promote a warm start.
– The accumulator dampens out the fuel pulses generated by the fuel pump. A large spring-loaded diaphragm to keep fuel pressure up with the engine off also dampens pulses from the pump.

4 – Fuel Filter
The purpose of the fuel filter is to filter the fuel so that it does not pollute the system. Keep the filters clean; we now recommend replacement yearly and water out of the tank (which goes for extended sitting with alcohol fuel), and the system lasts nearly forever.

5 – Warm Up Regulator / Control Pressure Regulator
The purpose of the warm-up regulator is to help enrich the fuel mixture during a cold start. The mixture is adjusted to the correct ratio when the engine warms up. This component can be overhauled, and we have had great success in cleaning and servicing these units, many of which are no longer available. An electrically heated bi-metallic strip operates a valve controlling fuel pressure to the distributor. Some units have a vacuum diaphragm that provides enrichment during acceleration.

6 – Fuel Injector
The injector provides a nicely atomized fuel to make the fuel-air mixture as homogeneous as possible. Not an electrical design; think of it as a mechanical valve that “pops” when the fuel pressure reaches approximately 45 psi (3 bar). All injectors in A K-Jet system spray at the same time the same amount; there is no timing as with a mechanical injection system. These are usually quite reliable, as long as water or debris doesn’t enter the fuel system. They do have rubber o-ring seals that need replacement from time to time.

7 – Cold Start Fuel
Discharged from the Cold Start Injector is present only when the engine is cranking over, as the operating voltage is derived from the starter solenoid.

8 – Cold Start Injector
Working in connection with the Thermo-time switch, the cold start injector adds extra fuel at very low ambient temperatures to assist when starting the engine. These only operate when the engine is cranking over, as the operating voltage is derived from the starter solenoid.

9- Fuel Distributor
The fuel distributor is the mechanical heart of the system, supplying the different cylinders with exactly the same amount of fuel. Some versions have an internal fuel pressure regulator to keep the system pressure constant. The main moving part is a central plunger which is controlled by the air sensor plate. When the throttle is opened, the increase of air into the manifold causes the air sensor plate rises and pushes the control plunger which allows fuel out to the injectors. Mixture adjustment is via the 3 mm Allen screw. This part can be serviced or rebuilt only with great care and proper tools. This is very easily damaged by debris or water in the fuel.

10 – (Mechanical) Air Flow Meter
The mechanical air flow meter measures the amount of air drawn in by the engine by employing a “teeter-toter” pivoting lever to access the metering plunger in the fuel distributor. Based on this measurement, the fuel mixture is mechanically adjusted. These are quite robust and rarely require service or adjustment.

11 – Frequency Valve / Timing Valve
This control valve is used with KA-Jetronic systems. Here the fuel mixture is regulated by means of a lambda-probe control system. The control valve changes the pressure between the upper and lower chamber of the fuel distributor, thus changing the fuel mixture.

12 – Lambda (Oxygen) Sensor
The lambda-sensor (only on KA-Jetronic) generates a signal that the control unit uses to adjust the fuel mixture. A special ceramic material that senses the difference between the O2 in the exhaust (or lack thereof) and the ambient O2 and produces a voltage that is sent to the Lambda Control Unit to adjust the CO in a closed loop system. The voltage fluctuates between a few millivolts and just less than 1 volt. The early single-wire (unheated) lambda sensor only generates a signal if the component has a sufficiently high temperature.

13 – Thermo-Time Switch
The thermo time switch controls the injection time of the cold start injector (8).  If a lambda control system is fitted, this sensor is also used as an input for the control device (computer) (18).

14 – Igntion Distribotor
It is not directly connected to the CIS system, noted only for diagram continuity.

15 – Auxiliary Air Valve
The purpose of the auxiliary air valve is to supply more air when the engine is cold. This air slide can be operated electrically or can be directly connected to the coolant system to change the system state.

16 – Throttle Position Switch / Position Sensor
The throttle switch is only used in systems with a lambda control system. This switch is present so that the control unit knows the throttle position for idle speed control.

17 – Engine Control Unit / Computer 
The control unit (ECU) processes the various inputs to provide the desired signal to the control valve (11), thus optimizing the fuel mixture. This unit is only present with KA-Jetronic systems or K-Jet with Lambda.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue and others; with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Finally
Questions or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.
Thanks!

Warmly,
The Atlantic Motorcar Center Service Team

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