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.

With Honor – A Life Well Lived, Extraordinarily Well

Case Studies
With Honor

When I first met Robert, he was referred to our facility to solve some previously unresolved problems with his classic 1998 Mercedes wagon. He was 95 at the time and informed me that he was interested in driving his Mercedes until he was 100.

I truly believed, given his grace, determination, and experience, that he’d make that. A very resolute, yet kind and gracious spirit. We solved the Mercedes wagon problems, and then he brought me his pride and joy, pictured here, a 1971 Mercedes 250C that he had brought over from Europe.

Robert didn’t quite make 100, passing away a few years back at 97. Ironically, this year, 2022, would be the 100th anniversary of his year of birth in his native England. Fittingly, we share this announcement.

 

But first, before we talk about the new area, let me tell you a little about Robert…

A most extraordinary gentleman, meeting this WW2 hero (how often do you meet a living Royal Air Force Spitfire pilot these days, especially one who shared a cigar with Winston Churchill?) and resurrecting his classic Mercedes was truly one of the highlights of my then 34-year career in automotive service.

After the completion of his first Mercedes, we sat in my office, talking about life and cars, when he suddenly spotted a Morse code key and practice sounder sitting on my desk. Being a ham radio operator, I frequently used it in my spare time to keep my Morse code sending sharp. Like a boy in a toy shop, he grabbed it up and began sending Morse code, a skill that he had learned some 75 years earlier in the RAF. I was delighted to gift him that, and so it was that when he would later call, I’d pick up the phone to the melodious tones of Morse code being sent.

If I may, I’d like to share the story of a life well-lived, very well lived. I knew he was extraordinary, but humble man he was, I didn’t know quite how much, until I read his obit. I knew I found a kindred spirit, didn’t realize how much. A part of Robert’s story can be found here – https://tinyurl.com/amc-robert-gray

So it was, when we bought our second location last July, we had some freed-up space at the main shop.
Discussions ensued, and our team agreed that it would be an ideal location to make a simple showroom, and there to display Robert’s car.

So a renovation was undertaken late last year, recently completed, the floor was epoxy coated with a wonderful vintage flake finish, the walls painted, cove molding installed, and antique lighting put into place. This is the result. We plan artwork for the wall and a couple of overstuffed leather chairs. I think Robert would be proud…

– Bruce
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That’s Hot! – Air Conditioning and Climate Control Diagnosis and Service

Case Studies

Air Conditioning In Modern European Autos
From the entry-level to the top-of-the-line, every modern car comes equipped with climate control. It is not just a feature; it is the standard. Audi, BMW, Mercedes, Mini Cooper, Land Rover, and Volvo, all have different designs, but the theory of operation of reach of these systems is the same.

Even though you might not get the heated seats or automatic climate controls, your car will still have A/C as standard. Interior comfort is one of the many reasons why we need a good air conditioning system in our cars. Often thought of only as a summer convenience, did you know that in modern cars, air conditioning is also used when the heat is on, to dehumidify the air inside the cabin, and to aid in defrosting the windows?

But then again, no matter how good anything was in beginning, it will always come to an end. Air conditioning is no different. They sure make our life a lot easier and more comfortable, but with time their cooling also starts to fade, and the system requires service.

Why Is My Air Conditioning Not Cold Enough?
Well, when you talk about A/C not working properly, it means that your A/C is malfunctioning. Now malfunctioning can be caused due to several reasons. But when we talk about A/C not being cold enough, well then, the reasons are always obvious.

If your vents are pushing less volume of air or you see dust or the air smells different, that will be a bad cabin micro-filter.

But otherwise, it could be a failed component or it’s just out of refrigerant.  To understand it better let’s first understand the working of a modern air conditioning system.

The functioning of an air conditioning system is nearly universally the same in almost all cars. The first thing you should understand is that your A/C does not create or generate cold air, it simply converts hot air into the cold. Your A/C system does so by either regulating the cabin air or bringing it in from the outside.

Understanding Air Conditioning Operation
It all starts from one unit called a compressor. It is a device that is used to reduce the volume of gas by increasing its pressure. Due to an increase in pressure the temperature also increases. Now, this hot gas moves into another unit called the condenser. The condenser is like a radiator and as the gas moves through it, it loses its temperature while being at the same pressure.

This in turn converts the gas into a liquid. Now the liquid moves through a dryer which separates the liquid from any remaining gas. Then the liquid moves to a thermal expansion valve which then simply turns your hot high-pressure liquid into a cold, low-pressure gas. The cold gas is now passed through an evaporator which is also like a radiator.

The hot air from the outside or from your cabin then passes through the evaporator. As the hot air comes into contact with the cold gas, the air loses its heat and you get cold air from your vents.

Then the cold gas from the evaporator goes back into the compressor and a cycle is created. This is how your air conditioning works. We would call it a heat exchanger, moving heat energy from one area to another.

How and Why Does Air Conditioning Fail?
You might be wondering, how does this explain your A/C not cooling air.
There are two answers to that.

a. Any one of the many AC components has stopped working.

b. Your compressor has run out of refrigerant due to a system leak, or the normal loss because of age.

What Is Refrigerant?
A refrigerant or freon is a substance used to transfer heat from one area to another. Yes, it is the same substance that keeps converting into liquid and gas as explained above. With time your car runs out of refrigerant and you need to recharge it.

Without refrigerant, your compressor will not work, and your evaporator will not have any cold gas to convert hot air into the cold.
But how would you know whether you have a malfunctioning AC or you just don’t have enough refrigerant?

How Much Does A Simple Air Conditioning Recharge Cost?
The total cost of getting your refrigerant refill or A/C simply recharged will generally not be more than $270-$300, but if a component replacement is needed, then the cost can be considerably higher. This is why it is important to have your system professionally diagnosed and checked for leaks, so parts are not needlessly replaced, or refrigerant wasted.

How Often Do You Need To Recharge Your A/C System?
Recharging your A/C doesn’t come with a time period or expiry date. Refrigerant is not consumed with use, but over time does seep out of the system, though this often takes years. So there is no time limit or frequency to how often you should recharge your air conditioning. It depends on the area you live in and the amount of time you use A/C and at what intensity you use your air conditioning, and system integrity.

The Proper Repair And The Alternative
If you search, you’ll see all kinds of “do it yourself” (DIY) kits to “repair and recharge” your air conditioning.  In days gone by, 20 or 30 years ago, this sometimes worked, when A/C had a “sight glass” to view the charge level.

Today’s modern systems no longer have a sight glass, and instead, rely on very accurate (down to the level of ounces) proper refrigerant charge. Any of these DIY kits will almost certainly damage your vehicle’s A/C system, and end up costing you hundreds, if not thousands of dollars more. DON’T TAKE THE CHANCE.

The only true and permanent repair is to confirm system integrity, correct any leakage, or replace worn or damaged components. Then the system must be thoroughly evacuated (vacuum drawn on the system for testing), a leak detection dye is then added, and then the system is properly recharged with the correct refrigerant, while pressure is monitored. It’s just not worth the risk, do it right the first time professionally, and it’s good to go.

Value
At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally
Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, 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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Glazed and Confused – Brakes, Brake Pad Glazing and Stopping the Car

Case Studies
Brake System – Caliper, Pads and Rotor

Not The Glazing You Hoped For
Glazing. At first, sounds like a sugary treat. But there’s nothing sweet about this service concern. No, it’s not a new donut, or frosting spread on your car’s brake pads, but rather something that adversely occurs to brake pad friction material.

A minor glazing issue will usually self correct. A major one requires professional rework of the brake system, to assure that you have a safe auto. So, let’s start out by talking about brakes, and how they work.

Process, How Brakes Work
To understand any failure, it’s first important to understand how the system is supposed to properly work. Automotive brakes are basically an energy conversion and storage system. The physics of car brakes are pretty simple. To slow down and stop your car, your brake system turns kinetic energy (the movement of your wheels) into heat energy, by way of friction applied by your brakes to the wheels.

This heat is then dissipated by the brake pads, brake rotors and though the brake fluid, into the air. Once all the kinetic energy of the wheels has been converted to heat energy by the brakes, your car stops. Pretty simple, right? By nature and design, brakes work in adverse environments, and do it well for tens of thousands of miles.

The Parts
There are five major components that make up your vehicle brake system – Brake Master Cylinder, Brake Lines and Hoses, Brake Calipers, Brake Pads and Brake Rotors.

Of these, the last three, pads, calipers and rotors, are the usual culprits in a brake glazing concern, as they are most effected by heat, and most subjected to adverse conditions. During normal street use, brake rotors and pads normally see temperatures climb past 200 degrees Celsius, or 392 degrees Fahrenheit! That’s almost double the temperature required to boil water.

These are also the parts that should be inspected, and serviced as needed, on a regular basis, ideally every time your vehicle is in for service. Of all the systems on your car, your brake and steering are arguably the most critical. 

Glazed Brake PadSo What Is Glazing?
Quite simply, brake glazing or “crystallization” is hardening of the brake friction material due to excessive heat. To complicate matters, the hard glazing typically transfers from the pad surface onto the brake disc (rotor).

That means the friction component is significantly diminished, resulting in reduced braking performance and often a noticeable brake shudder or vibration when brake pad material builds up unevenly on the disc. You may also see it manifest as cracks or fractures on the brake pads.

Glazing results in excessive stopping distances, and it can happen without the driver’s knowledge. It’s called “glazing” as the normally rough surface of the brake pads takes on a shiny, or frosted appearance.

Types
It’s important to distinguish between two types, one, which is light surface glazing, and is cleaned off with normal use in a few hundred miles.

The other, is deep and permanent glazing that transforms the structure of the brake pad, and often leads to cracking, or failure of the friction material.

Glazing Reasons
There are several reasons for brake pad glazing on passenger cars and trucks.

• Repeated hard and rapid braking at higher speeds raises the temperature to the point where it exceeds the limit of the pad material. This is usually evidenced by a strong and pungent burning smell.

• Driving with a foot on the brake pedal, called “riding the brakes” or dragging the brakes, keeps the pads in contact with the rotor. This constant rubbing spikes temperatures beyond the limits that passenger vehicle pads are designed for. Usually, but not always, evidenced by a strong and pungent burning smell.

• Continuous application of the brakes when coming down a steep hill can result in glazing. Often evidenced by a strong and pungent burning smell.

• Mechanical or hydraulic failure of the caliper can cause glazing. The caliper forces the pads to constantly rub against the rotor, like riding the brakes or coming down a steep hill.

This is the most dangerous cause of glazing because it often occurs without the driver’s knowledge. There are clues, a strong burning smell, and also the brake rotors will show signs of overheating, blue lines or areas of discoloration. Brake rotors may warp, causing brake pedal pulsation, or even get bright red and glow from the heat.

Glazed Brake Correction
Light Glazing, is self correcting, and will often clean off in a few hundred miles though normal brake use. This is the most common type and is often caused by “riding the brakes”.

Deep Glazing, where brake pad breakdown or damaged has occurred, can only be addressed in one way, the brake pads should be replaced and the rotors cleaned or replaced. Glazing compromises and ruins the friction material. The calipers and hydraulic system should be examined for mechanical problems or failure.

If glazing happens often, with no mechanical cause, the driver will need to evaluate their driving style. They may need to learn not to ride the brakes or to stop their vehicle constantly hard.

Other Options
Brake Pad/System change, though at Altantic Motorcar we are advocates to preferably install the factory designed parts, we realize that some clients will want to use their vehicles in different ways, some for performance or track use.

In these cases, we may be able to offer a superior designed brake pad, brake lines, or rotors, more suited to this level of “spirited driving”. Repeated failure of brake pads, with no underlying cause other than driving style, would be a good diagnostic indicator for this option.

Professional Brake Service
Brakes are one of those systems that appear low tech, and is often the first thing that folks tend to “farm out” or attempt themselves, thinking they are saving money. If there is one repair that we see again and again, that is subject to redo after a “DYI”, it is the brake system.

Over the last 35 years we have corrected more “do it yourself brake jobs” than any other system on the car. Incorrect parts, misdiagnosed, unnecessary repairs or parts replacement, seem to be the norm here.

On most European cars, calipers rarely need replacement, yet it’s the first thing we see done by those not familiar with these cars. Very often a waste of money, and a high quality factory part is replaced with a low grade aftermarket alternative. Likewise, brake fluid exchange, a simple service to prolong the life of your brake hydraulic system, is one of the most neglected.

Today’s complex ABS brake systems, electronic calipers, and computer controlled traction systems, require special training and equipment to service and diagnose.

The simple truth is that professional brake service, on one of the most critical safety systems of your car, is really no more costly in the end, by having a professional do it right, the first time. In fact, amortized over the life of a professionally serviced brake system, it’s remarkably inexpensive.

Atlantic Motorcar Workshop


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

We aim to inform you about the minor 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. Be sure it is properly performed, and take it to Atlantic Motorcar…Extraordinary Service for Extraordinary Cars.

Professional Team Members

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper, or other European (and now Japanese) import, 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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Mercedes Magical SAM Module – Solving Electrical Problems and Keeping SAM Happy

Case Studies

Background
This Mercedes presented with multiple external lights out, or not working correctly.

Locating the “SAM” under the coffee cup holder may not have been the best of design decisions. Then again, Europeans don’t really eat or drink in their cars.

So What’s A SAM?
SAM stands for Signal Acquisition Module in the Mercedes world. A SAM module receives data from sensors, switches, and controllers, and can send data, actuate (activate) components, and monitor systems.Mercedes-Benz has been using SAM modules since the mid-90s. SAMs come in a number of shapes and sizes, depending on where they are located on the car. Some are part of the fusebox, some are separate modules, most Mercedes usually have between four and five SAM units, depending on the complexity of the vehicle and systems.

Cool Technology
SAMs are very cool technology, replacing literally hundreds of discreet wires with a two or three-wire data network. They are usually super reliable and make your car more reliable…unless they get wet.

One of the top failures in the SAM control modules is water or in this case, liquid coffee damage, which leads to corrosion and eventual failure.

Typical Problems that cause SAM failure
Corrosion –  It is possible that the SAM control module may have gotten wet, corroded, and eventually failed. Typically this is caused because the repair is performed near the SAM control unit. If the SAM modules are not closed and sealed, properly they will eventually corrode. If a SAM module fails due to corrosion, at first you may notice that electrical problems are intermittent.

Excessive Current Draw – SAM control units don’t fail often. Other than physical damage or corrosion the next most likely cause to make your SAM unit fail is an excessive current draw. If you’ve done modifications to your Mercedes-Benz or have a module that is drawing too much current that can damage your SAM unit.

Broken Wires – Broken wires or shorts can cause your SAM module to fail due to excessive current draw. We this often with rodent damage or insulation that has broken down.

Incorrect SAM Coding 
– If you just had your MB serviced and now you have a different problem it is possible that there is a programming issue. During a repair, a technician may have reprogramed a new sensor but they didn’t complete all the needed programming. If this is your situation, t is important to read all fault codes before you start doing any troubleshooting on your Mercedes-Benz.

Correction
In the early model years, you could replace the SAM unit with a used SAM from another Mercedes-Benz and not worry about any programming. Newer Mercedes-Benz models require SAM module programming and the new SAM unit will need to be coded with the Sofware Calibration Number (SCN). You will need to replace it with a new one if you need a SAM. The new SAM module will need to be coded and programmed using the Star Diagnostic System (which we have at AMC) once it is installed.

The Proper Repair
The only true and permanent repair is to replace the SAM module and carry out programming, being certain that the cause of the failure, water entry, or other, is corrected.

Value
At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally
Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, please contact us.

Our team of Service Specialists is here to help, for even the newest autos!
Don’t hesitate to call us today, at (207) 882-9969.

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

Warmly,
The Atlantic Motorcar Center Service Team

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Sunroof Water Leaks And How To Prevent Them

Case Studies

Tech Tip – How’s Your Sunroof Drains?

Important Service Tip – Make sure your sunroof tracks are clean and clear as debris will find their way into the drain system, causing water to backup or leak inside your car. Pine needles, and leaves, both pretty common this time of year, are not your friends. This is especially true if you park your vehicle outside, somehow that stuff always finds its way in.

How – You can “Do It Yourself” by fully opening your sunroof, inspecting the track, and the areas underneath. Then carefully and manually clearing away all the debris you see in the track, in extreme cases, you might need to use a vacuum cleaner. Try to avoid parking under trees, espcaully pine trees, if you can help it.

Check The Drains – Make sure your sunroof drains are clean and clear by slowing pouring a cup of water on each side, near the drain holes, and observing that it drains away. Modern sunroofs are not designed to seal perfectly from water entry, some always gets through, especially in the large glass panoramic designs. This is what the drains are for, to handle the water that finds its way in, and to direct it down the drains, and not into the car. By the way, this design is always the prime reason why aftermarket sunroofs almost always invariably leak, as they do not have the water track and drain system, and rely instead on a perfect seal.

Clogged Drains
– Normally this water entry is not a problem, but when the drain tubes get clogged, all manner of havoc can break loose. These tubes are designed to take the water that makes it around the seal, and drain it down the front “A Pillars”, the metal channels on either side of the front windshield. Once these tubes clog, they often allow water to leak inside the car, making for a wet headliner, carpet, dash, or giving rise to all sorts of electrical gremlins. If you have clogged sunroof drains, seek immediate professional correction, before water entry damages your car, or its electronics. Be very careful about cleaning the drains with compressed air, or wire snakes, lest you disconnect, puncture or damage the drain tubes, requiring removal of the headliner of the vehicle to access and correct.

Twice Yearly – At Atlantic Motorcar Center, we advise checking these on a regular basis, and clean as needed, usually twice yearly. It’s important, if you are having your vehicle maintained elsewhere, to make sure this simple, but vital service is carried out. An ounce of prevention, worth a pound of cure.

All Cars – By the way, this is not use a Mini Cooper or VW problem, we see the same issue on Audi, BMW, Mercedes, Volvo, Saab, Lexus, and other brands. If you have a sunroof, check the drains, sooner, rather than later, and as noted, this is doubly true if you park outside.

Value – At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally – Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, 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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Mercedes Sprinter Service – Now In Midcoast Maine

Case Studies

Mercedes Sprinter Service – Now In Midcoast Maine

We are now open for Sprinter Service and Diagnostics here in the midcoast!
We follow the Mercedes Service Schedule, handle Check Engine and Warning Lights, as well routine Mercedes A and B Services every 10,000 miles.

Ensure your vehicle remains capable of great performance by servicing your Sprinter van with the professional service team at Atlantic Motorcar.
We’ll get you in and out, quickly and efficiently, minimizing downtime.

Our Bosch Certified Sprinter technicians use the latest technology to ensure that each vehicle is performing up to our highest standards,
and have the most up-to-date knowledge and technology, combined with factory parts so we can provide you with the high quality personal service, for you and your Sprinter!
3 Year /36,000 Mile Nationwide Warranty for your Peace Of Mind.

Please note that though we are a Sprinter Service Point, we are unable to accommodate very large Sprinter RV or box trucks to building limitations,
we are fine with most campers and work vans, so please call for information. 

Call Atlantic Motorcar Sprinter Service at (207) 882-9969 for prompt, professional service!

The AMC Service Team
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Don’t Knock The Humble Knock Sensor – Piezoelectric Knock Sensors – Design, Theory And Operation

Case Studies

Don’t Knock The Humble Knock Sensor – Piezoelectric Knock Sensors – Design, Theory And Operation

Knock Sensor – Waveform

What They Are
This is a quick technical dissertation will cover the design, function and how to test piezoelectric knock sensors on gasoline engine equipped vehicles.
Often buried deep down in the bowels of the engine, the knock sensor is one of those things that rarely fails, or is even discussed, until a problem occurs.
To put it simply, knock sensors are vibration sensors that are well suited to detect structure-borne acoustic oscillations.

Purpose 
This can occur as knock in a gasoline engine when pre-ignition or detonation occur (unintended combustion).
The knock sensor converts the engine knock into an electrical signal, monitored by the engine control module.
The engine control module uses this signal to counteract engine knock via ignition timing adjustments.

The Humble Knock Sensor

Theory Of Operation
Inside the sensor is a toroidal piezoceramic element with an attached mass.
The mass reacts to the vibration caused by engine knock, in turn causing movement in the piezoceramic element which generates an electrical signal.
This is the signal used by the engine control module as described earlier.

An engine will utilize just enough knock sensors to reliably monitor engine knock.
On four-cylinder engines one knock sensor can be used, as it can easily monitor all of the cylinders. As engine cylinder count increases, more sensors are needed.
Most times knock sensors are split into banks. For example on a six-cylinder engine, bank 1 may be cylinders 1 -3 and bank 2 would be cylinder 4 – 6.

A Volvo engine equipped with one sensor.

Knock Sensor Positioning

A Mercedes-Benz engine equipped with two sensors.

Knock Sensor – Mercedes 6 Cylinder Engine

Sensor are mounted to the engine crankcase and secured with a bolt tightened to s specified torque.
This tightening torque is important, under or over torqued fasteners could reduce sensor reliability.
Then sensor is mounted directly to crankcase with no washers to a machined and clean surface.

Knock Sensor Crankcase Mounting Location

Mounting Location

Testing
When sensors fail they can cause a few different faults. First of course if the sensor electrical circuit fails, you will receive a fault related to the circuit, such as a P0325.
This code refers to the sensor circuit, so it will likely be an electrical failure. P0326 may set, this fault code refers to sensor range / performance.
This can set due to signal out of range. The sensor can also fail, setting no fault codes but causing ignition timing to retard therefore reducing engine power.
This can be checked by viewing live data stream and confirming engine timing is being retarded.

When testing turn the Key On with the engine OFF, backprobe the sensor connector to check the bias voltage (this voltage is present for circuit integrity).
On most vehicles one wire will be battery negative (ground), the other will be reference voltage, 2.5 volts with connector plugged in and 5 volts with the connector unplugged.

Testing and Measurement – Knock Sensor Signal

Knock Sensor – Testing

Once you have tested circuit integrity and confirmed DC voltage is correct, you now have to test the sensor signal, which is an AC signal riding along the bias DC volts.
When knock occurs, the sensor will produce about spikes from 0 – 4.5 volts (depending on severity of knock).
You can lightly tap the area surrounding the sensor to manually test it. The sensor will produce a waveform as shown below.
You can also test the sensor using a DVOM in AC volt mode. Expect to see voltage generated in the same range as shown in the scope pattern.

Scope Pattern 1 – Knock Sensor Signal Without Knock Present

Knock Sensor – Waveform

Scope Pattern 2 – Knock Sensor Signal With Knock Present

Knock Sensor – Waveform

Still need help diagnosing an engine control input on any vehicle? Get in touch, we will get that vehicle fixed for you.

Value
At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally
Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, 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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Audi Electrical Diagnosis – HVAC Blower Motor and Control Module Failure

Case Studies

Awww Audi
Mike our shop foreman at the Atlantic Technical Center (ATC) discovered this today when diagnosing a HVAC fault in a client car. Nice call Mike! Now this is bad…whenever we find melted connectors, it’s what we call a “clue”, but also is a very interesting find, instructive even. Especially if you understand Ohm’s Law or E = IR, and also the relationship between heat and resistance, also known as P=I2R.

Great question!
Normally electric power is useful, making a lamp light or a motor turn for example. However, electrical energy is converted to heat whenever a current flows through a resistance and this can be a problem if it makes a device or wire overheat. In electronics the effect is usually negligible, but if the resistance is low but not close to zero (a wire or low value resistor for example) the current can be sufficiently large to cause a problem. You can see from the equation P = I² × R that for a given resistance the power depends on the current squared, so doubling the current will give 4 times the power.

What Happened
In this case, a worn blower motor was drawing much more current than normal, to overcome the friction of the worn bearings. Yet, not enough current to cause the fuse to blow, which would have alerted to the problem. As the worn bearings created excessive drag, which in turn causes the current to rise, more current equates to more heat at any resistance point. More current means any resistance in the system is going to get warm. Electrical connectors are the weak point, heat is generated there due to resistance. More heat causes tempered spring connection to fail and become loose, creating more resistance.

I agree, you’d think with that much heat, to clearly melt the plastic connector, and also melt the solder off the circuit board, that the fuse would fail, that’s what fuses do, right? It did not, but the resistance at the connector was turned into heat (P=I2R), and what it did do was melt the wiring harness, effecting the need for a wiring harness repair. And replacement of the melted module, and the worn blower motor. Schematic diagram is attached for you adventurous sorts. I love German wiring diagrams, so logical, and…well, so German.

The Proper Repair

The only true and permanent repair is to replace the blower motor, control unit, and repair the wiring harness. It’s just not worth the risk, do it right the first time, and it’s good to go.

Value
At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally
Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, 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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Let’s Talk About Steering Wheel or Tire “Pull” – Can Your Tires Really Be Cone Shaped?

Case Studies

Let’s Talk About Steering “Pull”
What can cause your vehicle to pull to one side? Let’s assume the obvious reasons have been rectified.
Your vehicle’s alignment has been checked and has either been re-set to the manufacturer’s specs or it is in good shape.
What could cause your vehicle to continue to pull to one side or the other?

Three Reasons Your Vehicle May Pull
There are three main reasons your vehicle may pull to one side.

  • Number One – And most common, you might have improper inflation in one or more of your tires.
  • Number Two – You might have severe, irregular or uneven wear on one or more of your tires, this is often caused by worn suspension parts, a lack of rotation, or an alignment issue.
  • Number Three – You might have a radial pull or “conical” pull caused during the tire’s construction.

Improper Inflation
Improper inflation, particularly on your vehicle’s front tires will certainly cause your vehicle to pull to one side. The wrong inflation on your rear tires, especially if your vehicle has a shorter wheel base, can also cause your vehicle to pull to one side. For instance, if one of your front tires has 35 pounds of air pressure and the other front tire has 28 pounds of pressure, your vehicle will pull toward the side with the smaller amount of air pressure. Not only is the tire with less pressure sitting just a bit lower than the other tire, but there is also more rubber contacting the ground with an under-inflated tire. More rubber contacting the ground causes the tire to grip the road even more causing your vehicle to pull in that direction.

Alignment Issues – Severe, Irregular or Uneven Tire Wear
Severe, irregular or uneven tire wear can cause a vehicle to pull to one side. If you have a newer tire with more tread on one side, particularly on the front of your vehicle, and an older tire with much less tread on the other side, the tire with the newer tread is going to grip the road better. Your vehicle will pull in that direction.

Tire Conicity and Radial Tire Pull
The third reason your vehicle may pull to one side could have been caused when the tire was built. This is called tire “conicity”, or sometimes, “radial tire pull”.
This is what this post is all about, the first two issues are easy to correct, where as tire conicity is much misunderstood.

Release the steering wheel and your vehicle pulls or veers (depending on servility) to one side. A front end problem, right, must be the alignment.
That pull is what most folks think of a wheel alignment problem. Surprisingly a tire can also cause your vehicle to pull. Tire “conicity” is a common phenomenon even in new tires.
Many people also call it a “radial pull” and sometimes a “tire pull.” You’ll see kinds of attempts to fix it, changing the air pressure in one tire only, shops that don’t understand issue trying to “fix it” with an alignment. None of that really works.

So, What Is “Tire Conicity”?
Tire conicity is where a properly inflated tire causes a vehicle to pull to the right or left when driven. Tires do not get conicity. They are manufactured them with the tendency. It is considered a defect and tire manufacturers cover tire conicity under their warranty, if we diagnose it properly and promptly.

Tire conicity or radial pull is usually different from a pull we feel with improper wheel alignment. A caster or camber related pull is normally constant, whatever the vehicle speed. This is because the misalignment does not change as the vehicle increases speed. When radial pull or tire conicity is the problem, the degree of the pull may increase with vehicle speed. It may be hardly noticeable at low speed and quite severe at 60 MPH or more.

Here’s An Example
You have a professional shop install a new set of tires on your vehicle and the wheel alignment is set. It is remarkable how well the vehicle now handles and drives. The driver can release the steering wheel and the vehicle tracks perfectly straight. The vehicle is a joy to drive. You smile, satisfied with your purchase.

Then it happens. After a few thousand miles it is time to rotate the new tires. After the tire rotation the vehicle now has a hard pull to the right. The pulling gets worse as we drive faster. What happened? Did the alignment suddenly go out? We perfectly inflate the tires, but the vehicle veers hard to the right when driving. A likely cause is tire conicity, a defect in a new tire.

A Proper Diagnosis Of Tire Conicity
Example – After a few thousand miles you have the tires rotated.  Now the vehicle has a hard pull to the right that gets worse as you drive faster.
What happened; Did the alignment suddenly go out?  As long as the tires are properly inflated, more likely is tire conicity, a defect in one of the new tires.
Diagnosis is straight forward; temporarily cross the suspected tire to the other side and see if the vehicle pulls the other way, or stops pulling.

  • We need no rocket science, because diagnosis of tire conicity is straight forward.
  • We first drive the vehicle to confirm the problem.
  • After test driving, we temporarily cross the suspected tire to the other side of the vehicle.
  • If the vehicle now pulls in the other direction, or stops pulling, it suggests tire conicity.
  • The tire on the side with the pull, is the normal cause.
  • To confirm the issue we rotate the suspected tire back to the rear.
  • If the vehicle again drives straight, we have found the problem tire.

Tire Conicity Is Different From Thread Separation
Tire conicity should not be confused with a separated, worn or damaged tire.
Though each of these problems can also cause a vehicle to pull, they are each separate issues.
Tire conicity or radial pull exists from the time we install the tire, because they build it into the tire when they manufactured it.

Why Does Conicity Occur?
Tire conicity results when tire belts are not perfectly aligned when the manufacturer builds the tire. Placing the layer of belting to one side creates the problem. Because more belting is on one side than the other, the tire surface inflates improperly. The side with less belting is not as strong as the other. Inflation pushes the tread out, more on the side with less belting. The result is a tire that inflates to a cone-shape, thus the name conicity.

When we roll a cone on a flat surface, it rolls in a circle toward the point of the cone. The same thing happens with a tire. This is why the vehicle pulls when the defective tire is placed on the front. When we place the tire on the rear, the effect is much less, but can also cause a pull if bad enough. We exaggerate the above illustrations for clarity. In reality we cannot see conicity with the eye.

When we install a new tire that has conicity on the front, the effect is obvious. It may go unnoticed when we originally install the tire having conicity on the rear. A driver may only notice the problem several thousand miles later, when they rotate the tire to the front and feel the pull.

Warranties – This Is What They Are For
The vehicle owner needs to notify the tire dealer in a prompt manner. Drivers require prompt action in reporting this condition to the tire company.
Tire manufacturers cover conicity under the new tire warranty, but quick notification is best. If you allow the tires to wear significantly, the wear may be [falsely] blamed for the pull and warranty may be much more difficult. Replacing the tire solves the problem.

Shops should not try to modify the wheel alignment to compensate for tire conicity.
The problem is the tire, not the alignment.
Changing the alignment will only result in the pull returning, when the tires are  rotated once again.

Prevention 
We suggest replacement only with quality name brands, Michelin, B.F. Goodrich, Pirelli, Continental.
These are the brands we use, with Michelin in particular being the brand we most often recommend for durability, handling and warranty.

Final
That’s our goal with each and every client car, fix it right the first time, and prevent problems from happening in the first place.
35 years of service experience have well taught us that “an ounce of prevention is worth a pound of cure.”
Be cured, once and for all, and give us a call, we’re happy to answer any service questions you might have on your Audi, BMW, Mini Cooper Mercedes, Lexus, Volvo or Volkswagen.

Earning your trust, every time you turn the key…that’s what we do…every day…for the last 30 years.
If you have questions, or if we can be of further assistance, just call us at (207) 882-969, we’d love to meet you, and your car!

Warmly,
Bruce and the AMC Service Team

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Land Rover Discovery II – Ignition Lock Problems, And The Correct Solution

Case Studies

The Problem
This Land Rover client presented us with a beautiful 2004 Discovery with an intermittent starting problem. We love Rovers, both old and new, and we also enjoy a good challenge!

On inspection, our Land Rover technician verified that the issue, and carried out a visual assessment. Then using the diagnostic computer we checked and scanned for codes, none were found, but did verify that the lock cylinder for the ignition had an excessive amount of wear.

The Proper Repair
The only true and permanent repair is to replace the ignition lock cylinder assembly with the housing, matching it to the client’s key sets, so the car does not have two different sets of keys. The challenge arises that the part seems to be nearly obsolete, and were quoted a “maybe” 5 week delivery time from the UK.

We were able to buy a new lock cylinder with a “generic” key set, and then disassemble, and rekey the lock cylinder to match and work with our client’s existing keys. When doing this, it is important to have both sets of keys, as wear may have occurred on one key, and if the cylinder is not coded to work with both sets of keys, the client may be locked out of the truck.

Value
At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Finally
Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, 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

Read More

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