Dealing with a bad brake at church

Posted on 05/10/2017

In September, I wrote about electric emergency brakes. At the end of the column, I told everyone to read their owner’s manual to have a better understanding of their brakes if they encounter a problem.

The subject recently hit close to home.

My wife drives a 2011 BMW X5 diesel that just so happens to have an electric emergency brake. I noticed that her electric emergency brake switch was getting loose, but I kept telling myself that I would order the part and install it when I got a chance.

While driving to church, I looked down and saw that the e-brake switch had broken off. I asked my wife what happened, but knowing the switch was already loose, I didn’t press the subject. I also realized that I could still line up the broken tab and possibly position it well enough to make it useful.

As we arrived at church, I found myself in a predicament: Should I engage the e-brake or not? In the back of my mind, I somehow thought it would be kind of a cool experiment. So I did it. At that exact moment, my wife turned to me and exclaimed, “Why did you do that? You know it’s broken.” I, being Matt the Mechanic, of course replied, “It will be fine.”

As we emerged from church, collected our children and headed to the car, I couldn’t help but feel a little excited – I was going to prove to my wife that I could just line up the tab and release the brake instantly.

Yet we all know that it didn’t go that way.

The moment the e-brake did not release, my wife sternly reminded me that our oldest son had swim practice in 20 minutes and that I better get this sorted out right away.


I quickly sprang into action. I knew where the manual emergency brake actuator was (left side of the trunk area), but I had never attempted the manual release procedure. While I accessed it, I politely asked my wife to please read me the instructions on how to release the cable.

This is where things got interesting.

As the rear hatch came up, I discovered a bike, a scooter, a helmet, two strollers, another bike and miscellaneous sand toys. It was as if we were in a BMW commercial on what you could put into the back of a midsized SUV.

As I began to unpack the payload, my wife quickly read the instructions and reminded me that we now had 15 minutes to get to swim class.

Once I cleared the rear of the vehicle, I accessed the left rear panel. I could see the release cable. My wife told me to remove the plastic tool from the car tool kit; it’s red and looks like an L. I then inserted the tool over the cable and pulled hard.

At that moment, I found myself crouched in the trunk, sweating in my Sunday best with what looked like a yard sale in the back of that car. People were beginning to stare.

I was sure relief was in sight – I was just about to release the e-brake and save the day, but, no, it did not release. I pulled harder and harder. I then got an update from my wife that I was not pulling hard enough and we now had 10 minutes to make the swim class. On top of that, our oldest was saying that he did not want to go to his swim lesson and our youngest was screaming at the top of his lungs.


I tried a few more times but realized that it was not going to work. At that moment, I sat calmly and asked myself, “What would I do at the shop?” I exited the trunk and sat in the front seat. I retrieved the broken tab and examined it. I noticed that it was a dual cantilever system.

I figured out what would release the switch and asked my wife for something sharp from her purse. She gave me that look that indicated, “Why in the heck did you set the e-brake in the first place?” She then gave me a pen. I removed the clip from the end, inserted it into the correct position of the switch and heard the glorious sound of the e-brake releasing.

I have to admit that I was kind of laughing inside during the entire episode, because I had just written about being prepared for such an incident. It is just another reminder that no matter what you do, life is always going to throw you a curveball. In the end, our oldest made his swim lesson and we enjoyed the rest of our Sunday.

Matt goes full throttle to fix BMW

Posted on 05/10/2017

In November 2015, one of my newer customers brought in his 2011 BMW Z4 35i because the service-engine-soon light went on.

He explained that the car did not idle well and was low on power. We connected the car to the Integrated Service Technical Application, because it was a post-2008 BMW, and were able to pull several codes related to the primary operation of the engine.

We pulled Digital Motor Electronics (DME) codes: DME 002CF6 Throttle valve potentiometer 1 – plausibility to air mass; DME 002CF7 Throttle valve potentiometer 2 – plausibility to air mass; and 002D2E DME Throttle valve angle – intake vacuum correction.


But one must be careful when reading codes. It would be easy to think that there may be a problem with the throttle body, but the third code is extremely important (DME 002D2E Throttle valve angle – intake vacuum correction). The correction code indicates that the volume of air entering the throttle is not the same amount being processed by the engine.

This air-to-fuel correction is called fuel trims, or lambda. A higher amount of fuel indicates that the system is rich, and the higher the ratio of air indicates that the system is lean. So we tested the throttle body and reset its adaptations.

We reviewed the data and saw that the car was running lean. The next step was to smoke-test the intake system. Once we started to pressurize smoke into the intake system, we noticed that it was escaping through a crack in the valve cover.

The late-model BMW valve covers house the crankcase breather valve. The breather valve takes unburned fuel and oil vapors from the crankcase and recirculates them through the intake so that they won’t escape into the atmosphere. The extra air pulled into the valve cover drives the fuel trims lean and starves the intake of fuel. The extra air would in turn cause a rough idle and poor acceleration. We replaced the valve cover and corrected the fuel trims.

Problem solved – or so we thought.


Eleven months and 3,800 miles later, the customer called to tell us that the service-engine-soon light went on again. He stated that the car was intermittently idling rough.

All three codes were back, but when we examinded the fuel trims, the car was not running lean. We then smoke-tested the intake and found no leaks.

We thought there might be a vacuum leaking internally. We performed an exhaustive smoke test on all intake-related systems and found no leaks.

The interesting thing was that as soon as we cleared the codes, 002D2E would come back within 1 mile or so of driving. Normally, it would take at least 10 miles of driving to set a fuel trim code.

We then checked the mass air sensor to see if it might be physically damaged. We found it contaminated with oil – it had gotten into the intake system when the valve cover/breather was cracked. The oil vapors were causing the sensor to read incorrectly.

We replaced the main air mass sensor and the car immediately sent code 002F0A – intake air-turbo sensor signal for the secondary pressure sensor. We replaced both air pressure sensors.

After driving the car for 10 miles, the check-engine light returned. The accompanying code read: DME 002D07 throttle.

This is where it gets crazy – there was no explanation for the code.

We contacted BMW’s technical support department and discovered there was no data for the code. While we continued to run diagnostics on the throttle, we checked the car’s software level. We found that it was operating on its original base programming and that there were multiple module and program updates available. We then performed a complete car reprogram and all available adaptions. After that, we drove the car for 280 miles without any problems.

When the customer picked it up, we told him that there was still a possibility that the throttle could have a problem, but at this time we felt that the mass air sensors and the reprogramming were adequate for the repair. We did not want to change the throttle unless it was absolutely necessary.


One month and 550 miles later, the service-engine-soon light lit up again. The codes: the DME 002D07 throttle and the 002CF6 throttle valve potentiometer 1 – plausibility to air mass. We then triple-checked all of our data and replaced the throttle.

This was one of the most challenging and exhaustive repairs we had ever performed. I personally do not want to say everything is OK until a year from now. The valve cover had caused fuel trim problems in three systems, yet there was also an intermittent problem in the throttle that was being blocked by the fuel trim codes. This reminds me to stay updated with as much information as possible and be patient with each repair.

Outback overheating issue comes to a head

Posted on 05/10/2017

A new customer recently brought his 1999 Subaru Outback to the shop. The man said the car was overheating and making noise whenever he drove it.

Because most of the time I write about complex diagnostic scenarios, I’m sure that many of you think this is going to be a column about a really tough cooling-system problem.

But that’s not the case; the cooling-system problem was the typical Subaru 2.5-liter head-gasket failure. I am bringing up this problem to discuss the anatomy of the failure.


I first must explain the different types of motor configurations. There are four configurations of internal combustion engines: inline, V, boxster (flat) and rotary.

Inline engines are those with cylinders that are literally “in line” – lined up back-to-back. The most common inline motors are 4, 5 and 6 cylinders.

The “V” used to describe a V6, V8, V10, V12 and V16 does not actually stand for a word, but instead the shape of the piston arrangement.

The boxster motor has horizontally opposed pistons. Boxster motors come in 4 and 6 cylinders.

Rotary engines use a triangular-shaped rotor that spins, unlike the typical piston engines. There are 2- and 3-rotor engines.

All four designs have their benefits and drawbacks.


Because the Subaru has the boxster motor, I will focus on it.

All Subaru motors are boxster style. The pistons on a boxster motor lower engine vibration to almost nothing because of the counterpunch dynamic. The lower engine height also lowers the overall center of gravity of the vehicle, which improves handling. In addition, the lower configuration enables the engine to fit into a smaller area.

Along with Subaru, cars made by Porsche and early air-cooled Volkswagens feature the boxster design.


So let’s get back to the Subaru’s head-gasket problem. The most common problem with a boxster motor is engine oil leaks. Because the pistons are horizontally opposed, the cylinder heads are on the outside of the engine. When you turn off a boxster motor, the hot engine oil takes longer to return to the oil pan.

Additionally, the hot oil may come to rest on top of the head gaskets and valve-cover gaskets. Over time, the hot oil literally cooks the gaskets.

With the inline, V and rotor designs, the pistons or rotors sit directly above the oil pan. When a non-boxster motor is turned off, the hot oil returns to the oil pan much quicker and does not have an opportunity to stay behind and cause problems with the gaskets.


It’s extremely difficult to know when a Subaru head gasket is failing. That’s because it leaks or burn coolants so slowly that the customer does not know that there is a problem until his or her radiator is low on coolant.

The head gasket has a thick steel core with two coated outer thin metal gaskets. These head gaskets have a tight tolerance, so they leak slowly. The Subaru head gasket can seep oil for extended periods of time before it becomes a problem. But once the gasket coating starts to disintegrate coolant, oil will begin to leak. And once the coolant begins to leak, the head gasket must be repaired.

The best way for Subaru owners to avoid this is to follow the car’s maintenance schedule closely. It is also important to use Subaru or factory-quality engine oil and coolant. And don’t forget to check the engine oil and coolant level at least once a month.

Solutions for two problems in one day

Posted on 05/10/2017

I recently had two customers bring me two common problems on the same day, so I thought that it would be interesting to bring these issues to light.

We had a 2004 Acura TL with a power-steering pump whine and a 1999 Toyota Camry XLE V6 with no idle when cold. I find these problems interesting because there is no built-in warning light or technical code to identify them.

The Acura owner told me that when he starts the car in the morning, he hears a whining noise in the background that increases when he turns the steering wheel. Acura hydraulic-power-steering systems use a power-steering pump, power-steering reservoir, power-steering rack (rack and pinion) and power-steering hoses that tie it all together. The power-steering fluid starts in the reservoir and is pulled into the pump through the suction hose. The pump pressurizes the fluid and then delivers it to the power-steering rack. Once there is pressurized fluid at the power-steering rack, the steering wheel turns easily – even if the car is sitting still.

The benefit of a hydraulic system is the ease of power transmission and stiffness. Therefore, if air somehow gets pulled into or is introduced in the hydraulic fluid, the hydraulic will lose its stiffness. The air will also cause cavitation damage and severe fluid degradation. Therefore, as soon as air mixes with the fluid, the pump cannot properly pressurize the fluid. The power-steering pump is designed to pressurize fluid – not air. The air then causes the power-steering pump to make a loud whining noise.

There are two hoses that go to the power-steering pump. The suction hose pulls fluid from the reservoir, and the pressure hose pushes fluid to the rack. There is a small adapter on the pump that connects to the suction hose. The adapter mounts to the pump with a bolt, but it is sealed by a rubber O-ring.

The pressure hose also seals to the pump with a rubber O-ring. Over time, the rubber O-rings shrink and stiffen up. Once the O-ring hardens, it loses its sealing quality. So as the pump pulls in fluid through the suction hose, it also pulls in air because of the worn O-ring.

Once the suction O-ring is replaced, the pump stops pulling in air. We also recommend replacing the pressure side O-ring, because it will tend to leak.


That same day, we had a 1999 Toyota Camry that could not idle at all when cold. The customer reported that when she starts the car, it dies, and she has to keep her foot on the accelerator to rev up the RPMs to drive it.

This Toyota V6 is fuel injected and uses a throttle body for air delivery to the intake manifold. If the throttle plate is shut, there is almost no air traveling to the intake. Without air flowing to the intake, the engine won’t run. So there has to be a secondary air bypass to keep the engine running while the throttle is shut. This secondary air bypass is called an Idle Air Control (IAC) valve. The IAC, which enables air to travel from one side of the throttle plate to the other, will help control the idle when other consumers such as the air-conditioning system or the power steering steal horsepower from the engine during idle. There is a small gate inside the IAC that can change the flow of air during all of the different conditions of idle.

Throttle bodies have a tendency to build up carbon over time. Because the IAC valve is mounted to the bottom of the throttle body, it also begins to build up carbon. Once carbon fills up inside the IAC valve, it can get stuck. The carbon is harder when cold and tends to loosen a little when warmed up. We removed the IAC valve and found the gate jammed with carbon. We cleaned the valve and reinstalled it.

Both of these problems took only a couple of hours to solve and were easy on the budget.

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