I drive a 2000 Saturn Wagon, and am generally pretty happy with it. It’s roomy enough for a big guy like me, carries my stuff around, gets decent mileage, and is fairly trouble free.
Except sometimes.
Every once in a while, the damned thing decides to stall. Usually this happens when the engine is cold, and particularly when the air conditioner is turned on. There have been times that I have had to sit in my parking space gunning the motor for ten minutes or more, because each time I took my foot off of the accelerator for even a moment the engine would die. Usually, by this point in time I would get impatient, and (if traffic was light enough) I’d shift into Drive and starting moving down the street. As long as I was accelerating, it was fine. Each time I’d reach a stop sign, though, it would quit yet again. Only after I had actually driven for two or three miles would it operate normally.
Try as I might, I’ve never been able to nail down a pattern for when this happens. I can go for months without a single instance, and then, suddenly, it happens again. Last week it started happening after I had already driven a couple of miles, but was stuck in bumper-to-bumper traffic on the freeway. Drive ten feet. Stall. Shift into Park. Restart engine. Shift into Drive. Repeat about fifteen times. Rip out hair in frustration.
I attempted numerous times to bring this to the attention of the mechanics at the dealership where I bought the car. Each time I’d complain about it, they’d keep the car for one or two days (so that they could test it when the engine was cold) and then announce that they’d been unable to find anything wrong. And knowing the car the way I do, they were probably telling the truth.
So can any of our automotive gurus point me in a likely direction? What sort of things could cause this? What steps can I take to rule out potential cause x or y?
When you find out, let me know. My car does the same thing, but only when the engine is fully warm. My mechanic drove the car for a week and couldn’t get it to act up.
The mechanic thinks my problem is the fuel pump, but says that’s far too expensive a repair to try as an experiment.
Let take these in reverse order. kunilou I odubt very much that it is your fuel pump. Electric fuel pumps (what is used on modern fuel injected cars) are a lot like a light bulb. Either they work or they don’t there is very little middle ground, and very rarely do they go intermittant. (Johnny LA’s MG is the exception to this rule BTW) it is possible to have a fuel pump not deliver enough pressure, but usually that shows up as a preformance problem, not a stalling problem
Possible causes of an intermittant failure to idle could include a dirty throttle, a dirty or sticking IACV (Idle Air Control Valve), dirty or plugged fuel injectors, electrical gremlins causing a sensor to read incorrectly, but not far enough out to set a check engine light, or air leaks.
If I were going to diagnosis the car, I would start with checking and repairing any and all vacuum leaks. That would include hoses that could be cracked or disconnected, manifold gaskets that might be leaking. I also make sure that all the intake hoses are intact and do not have any holes. A hole in an intake hose past the mass air flow sensor will make the engine not get enough fuel for the amount of air that is going into the engine. The air that leaks in, that is not measured, is called pirate air. (ARRRRGH matey!)
If that did not correct the problem, I would move onto cleaning the throttle, and a good visual inspection of the wiring harness on the engine. I would be looking for a damanged or worn harness.
At that point I would clean / replace the injectors and or the IACV. If the problem still persists, I would wait for the next time it occurs and take it to the shop right then.
If you take it to the shop during the malfunction, it should not be difficult for a professional technician to nail down the cause.
I had the stalling when warm problem with a 1998 Camry, which turned out to be the result of a sticking EGR valve. Hard to trace down, and expensive to replace, unfortunately. YMMV.