Passat Mystery Problem

Maintenance/Repairs
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1

I am stuck. I have a 2002 Volkswagen Passat, and I have been having a couple different issues that no one has been able to explain (or there have been too many explanations). The main issue started a few months ago. Any time I drive long distances I stop to get gas and my car has a difficult time starting up. It takes a longer turn of the key, or sometimes it will take more than one try to get it started. Then once it starts the car makes a “womp womp womp” sound, and the tachometer (? the gage on the left hand side of the dashboard) passes back and forth from 0 to 10 until it finally calms down. Also, the check battery light comes on if it doesn’t start the first time. This ONLY happens after I have been driving for a few hours at a time during car trips, and I think it has gotten worse recently. I went to AutoZone to get my battery checked. That was a terrible mistake because they just confused me further. They said the battery was fine (which I would hope, because I just replaced it a little over a year ago). They said the alternator was fine, and no error codes came up when they tested my starter. One kid told me he thinks it is the fuel filter, or the fuel pump. Another lady said that if your starter is wearing down it gets flat spots, and sometimes your car will land on those flat spots and it will be hard for your car to start (this ignores the fact that it only happens after long car trips, and it sounded like gibberish to my mechanic-challenged mind). The manager said that the starter could be swelling in the heat, making it hard to start. AHHH!! Too many unsure people in one store! I took it to the Volkswagen dealership to get an oil change, and for them to check if anything was wrong. They found nothing. HELP.

Not to mention about a month ago I stopped at a stop sign, and I went to speed up again and nothing happened. My gas pedaled stopped working. The engine wouldn’t rev, and the car was still running. When my car cooled down again it seemed fine. I took it to a mechanic and they found NOTHING wrong with it. My dad thinks it is the fuel filter.

If anyone could help me I would be so happy. I am so confused, and I have to make an 11 our car trip back to school soon. I would hate for something to go wrong, and get stuck in the middle of nowhere.

Thanks

2

The battery light comes on when you don’t get a car started. That’s normal.

You say it happens when you get gas so clearly it is related to that.
What happens when you pretend to fill up? In other words: open the gas tank, close it and see if it wants to start. It it does, the process of filling it up does something to your car.
It it doesn’t, opening the gas tank does something. It would give us a clue.

Btw, you don’t necessarily have to do it at a gas station to try that^ - I doubt the car knows the difference where it is. :slight_smile:

3

Well I say it happens when I fill up only because it happens when I have been driving for a few hours constantly. So normally when I stop it’s to fill up my gas tank to continue on the road trip. However, it isn’t because I am low on gas. It did the same thing when I had half a tank, then filled up. Also, I filled up and tried to start (it had problems starting), then I had to go into the gas station to get food and such. When I came back out it did the same thing. It just wasn’t as hard to start. I assumed that it was because my car had some time to cool down.

4

Well, that’s what I’m asking:
Is it because you’re stopping after a long drive - or -
opening the gas tank after a long drive - or-
filling up after a long drive?

Since you mentioned ‘filling up’, I’m wondering whether that is an important detail or not.

5

No wonder you’re confused. I’ve spent the past 5 minutes looking at your post trying to figure out where to begin.

If I understand you correctly, the engine’s starter motor is turning the crankshaft over, but when the engine is warm it isn’t starting as easily, and it gets worse as it gets hotter. The starter won;t provide any fault codes, so that’s a blind alley.

The “flat spots” the lady referred to are often also called “dead spots”. The starter consists of wire coils wound around “arms” off of the spinning center rod, often called an “armature”. They’re energized (magnetized) as the armature spins by being connected to segmented contacts called a “commutator”. Sometime, either a commutator segment will wear out or a coil will break (or short), creating a “dead spot” in the motor. If the starter motor should stop on that “dead spot” it wonn;t have magnetism t get it started again until connection is again made through the armature or it is somehow moved past that spot…often by banging the motor assembly. That is not your problem. If that were happening, the motor would not turn the engine’s crank shaft. Besides, it would not cause a “womp womp” sound once it starts or cause a fluctuating needle.

The “swelling motor”… nope. While a starter motor can become heat sensitive, if it did it would not be turning your crankshaft. What would happen is that starter would fail to turn your crankshaft reliably when it got hot. And it wouldn;t be a swelling problem, it would be a winding problem. Dismiss that as a likelihood.

The needle fluctuating…I suspect that’s happening because a lot of cars now “sweep” the needle to full scal with every start up…and I suspect that your engine is starting erratically, thereby “sweeping” the needle more than once. Once you conquer the starting problem, I believe your needle problem will go away.

I believe the “check battery” light is recating similarly, doing its “check” lightup with every erroneous start. Again,

Now, to the actual problem.
It may be the fuel filter or fuel pump, especially since it would not respond to your gas pedal inputs recently. It may have been starving for fuel. Fortunately, that can be tested with a simple test kit. And shop can do this for you.

Another possibility is a failing ignition component, either a coil pack or igniter. These can become heat sensitive, Understand that your underhood temperatures rise when you stop. Your exhaust manifold and the areas around your cylinders are much hotter than the “engine temp” measure by your temp gage. When you shut the engine off, the coolant stops circulating, the fan stops running, and that heat migrates out the surfaces of the exhaust parts and the engine and heats up the engine compartment. Because of the way coils are made, the insulation can over time break down and allow shorting of the windings when they expand from heat.Then when the engine compartment temp cools off again, the insulation breech closes and the coild works again. A coil pack failure would not be an unusual failure after the coils’ having been thermal cycled for 10 years.

6

Yup, those things are definite possibilities.
Maybe the cranks sensor as that clearly affects it running like junk and also indirectly runs the tachometer that jumps all over the place.

Too many possibilities right now.

7

If the car fails to start on the first attempt, on the second attempt a kind of wooop, woop, sound can occur due to the extra fuel injected the first time, as part of the car’s normal starting procedure. Since you had to start it twice, you ended up w/unburned fuel, which had to burned out the second start. Hence the likely source of the weird noise.

The hard to start problem could be caused by a lot of things. Has your car had a tune-up recently? If not, that’s probably where I’d start. Especially since you are facing a long trip. You want to be safe.

Since the check-battery light comes on occassionally, make sure all the battery connections have been properly removed, cleaned, and re-tightened, and I’d probably get a second opinion on the battery itself. You need what is called a “load test”. In my area Sears Auto will do this for free.

There’s some possibility the weird sound is caused by the starter motor going bad, but because it seems to crank ok, I doubt this is a starter motor problem. If you turn the key and sometimes nothing happens at all, maybe just a click, that is the more common symptom of a starter problem.

Now the second problem, where you stepped on the gas and nothing happened? To me that sounds like a mechanical problem with the connection between the gas pedal and the throttle. If the pedal was hard to push, sort of stuck, that means the throttle body needs to be cleaned. If the pedal just went to the floor and nothing happened, that means all the mechanical devices from the pedal to the throttle control at the top of the engine need to be visually inspected.

Best of luck.

8

Hmmm, anyone thinking that an injector is sticking open after a long drive? Open injector will cause loss of fuel rail pressure causing a no start or extended start until it closes again. BTDT.

Problem is we really don’t know if the starter is turning or not or if its heat soaked, if there is fuel pressure, spark, or anything else when there is a delayed start. Either going to have to carry some diagnostic tools like a spark tester or fuel pressure tester to get anywhere, or she’s going to have to find a shop and then drive right there after an extended drive to have them hook everything up to test it.

9

this car is drive by wire no throttle cable

10

How long of a trip do you need to go on for this to happen. I assume the car is driven locally and you have no issues with that, so how far do you need to go before the car acts up?

11

Unfortunately this isn’t going to solve the OP’s problem with too many diagnoses, but I think the problem is electrical and has something to do with ECU connections. IMO all of the symptoms can be explained by corroded connection(s) and or a poor ground connection to the ECU. Plus I think Volkswagens are prone to this type of problem. First thing I would do is disconnect all of the connectors and look for corrosion, and check the ECU ground.

12

I don’t think we can with any kind of certainty say what’s wrong with that car. We simply don’t have enough information.

13

If the 2002 Passat is indeed a drive-by-wire design – that’s surprising to me, I didn’t think they had that in 2002 – then @MTraveler is on the right track. Some kind of electrical connection problem caused by oxidized connectors would be the first place to look to find the cause of the non-working accelerator pedal. If the car has been in an accident or has had extensive repairs, such as a new engine or new head, then a missing or loose ground is a good possibility too.

14

Have someone check for a defective Mass Air Flow sensor. VW’s of this vintage are notorious MAF sensors failing. A co-worker had a 2003 Jetta where the MAF sensor would fail every 6-9 months. This problem got so bad that the dealer dropped the price of the MAF sensor from $169.00 to $29.00 because they didn’t last long. And people complained.

He finally sold the vehicle because he couldn’t take the chance of the vehicle breaking down with a new-born.

But by now, I’m sure all the replacement MAF sensors have been redesigned so they last.

Tester

15

hey, I am having a somewhat similar problem see " unsolveable problem" posted 8/23/12. the throttle doesnt respond all the time, haven’t noted any trouble with starting, or gas fill ups, will keep you posted if they ever figure out what is causing it for me- I still have mechanics looking at it