QuestionHello! I have a 1997 Buick Le Sabre and usually runs fine, but recently it has been stalling while I am driving. It has not created a huge problem yet because it starts right back up. It stops more frequently when it is in idle, or when I am driving slowly. I want to fix the problem before it gets worse! Thank you for your time
Anna
AnswerHello Anna,
There are so many possibilities, I can't cover them all.
But more than likely, it is due to one or more sensors not sending the correct information to the the "computer", or ECM.
The ECM uses the information to calculate the air/fuel mixture and ignition timing for whatever driving conditions exist at the time...several times per second.
An improper signal from a sensor will cause it to send the wrong fuel/timing.
Say for example the coolant temperature sensor is out of range, and tells the ECM the engine is colder than it really is. The ECM will send a richer fuel mix, similar to an old choke system in a carbed car.
A dirty mass airflow sensor will send an incorrect signal, and again, you end up with a wrong mix.
If you go to Autozone, they will connect a scan tool to the car, and there may well be stored fault codes, even if the service engine light isn't on. That would be the first step to take.
Don't just buy parts if it says something like oxygen sensor rich, or lean, etc.
A lean reading, for example, could be correct, but caused by something else, such as the EGR valve sticking open, which could easily cause the engine to die, since it is like a huge vacuum leak.
Cleaning the EGR valve, cleaning the idle air control valve, checking the fuel pressure are three things that are cheap, and should be done before doing anything else.
Then see what the codes are, and go from there.
Here are a few links you should read.
http://www.fordscorpio.co.uk/cleanmaf.htm (Ford, I know, but read it. The MAF's work the same.)
http://www.fordscorpio.co.uk/maftest.htm
http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279
Van
