Car (Almost) Stalls on Cold Start


#1

1991 Buick Regal, 3800 V6

As the title says, when I start the engine cold I get a slight puttering and drop in RPMs followed by the engine revving itself to about 1100 for a few seconds and then normalizing at 600. It has only actually stalled out a few times. This does not happen once the engine is near operating temperature.

Now, I did not notice this issue prior to doing some maintenance on the vehicle (radiator replacement and transmission service) and I’ve read that this can be caused by a faulty coolant sensor. Possible?

Battery is new.

Also, when I say cold start I mean summer temps here in Michigan. So it’s happening anywhere from 50 to 90 degrees F.

Thanks.


#2

There is a temp sensor that lets the ECM know if the engine is hot or cold and adjusts the fuel mixture accordingly. The other issue may be a dirty IAC. The MAF feeds the ECM for the IAC and it may need cleaning with sensor safe cleaner.


#3

So, this is getting progressively worse (or perhaps it’s the increase in humidity over the past week). It’s stalling out on more than half of cold starts. Odd thing is, it starts fine after an 8 hour shift at work, but only has this problem after sitting overnight for more than 12 hours, irregardless of the outside temperature.

I’m not wondering this: Can this cause any potential damage to the engine or ignition system other than advance wearing of the starter?

I haven’t had a chance to try cleaning any sensors yet, but it occurred to me that something may have gotten wet. There was flooding here a few weeks ago and the car got hit by a fairly deep wave of water when moving it to higher ground. It did not stall and the air intake looked bone dry upon inspection. I cannot recall if this issue started before or after the flood.


#4

You really need to look into the items knfenimore suggested. It’s sound advice.


#5

No, nothing is being damaged by hard starting. But faulty temp sensor is quite possible and inexpensive to replace.


#6

Leaky fuel injectors can flood the spark plugs with fuel. Try giving it full throttle while cranking for a few seconds. Then try again with the foot off. If that works, that would confirm the engine flooding.