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-   -   Over-revving in the cold...and engine cleaning. (https://www.gmforum.com/1992-1999-91/over-revving-cold-engine-cleaning-212332/)

96LeSabre 02-03-2005 04:49 PM

Over-revving in the cold...and engine cleaning.
 
Anybody have any idea what would cause a car to rev excessively during warmup after sitting in the cold. I know that the car will send extra gas and air to help the car warm up faster but my car hits 3000 RPM in park! My next problem is that when I put it into gear before it warms up quite a bit the RPMs stay too high, I gotta keep hitting the brakes to slow it down. Sometimes when I put it back into park after warming up more it will go back to normal idle speed but this seems extreme. My car once hit 75 in a 55 because of this problem without me hitting the gas. Also not on topic with my main question but in an article that was posted on cleaning the throttle body it mentioned about pouring Seafoam through where the PCV valve goes while the car is running...is this normal procedure for this product, is it harmful?

MOS95B 02-03-2005 04:52 PM

Try cleaning the throttle body? Sounds like the choke may be sticking....

96LeSabre 02-03-2005 04:57 PM

Would that cause it to happen only in the cold? It never happens in warmer weather only in freezing temps or around there.

1993 SLE 02-03-2005 05:02 PM

the car will always have a higher idle when the car is in cold weather

96LeSabre 02-03-2005 05:05 PM

I know that it will idle high, but isn't 2500-3000 RPM extreme? Also when I put it into gear shouldn't it drop back close to normal not so high that it can accelerate up slight hills on it's own?

MOS95B 02-03-2005 05:08 PM

The cold could cause whatever gunk is on the butterfly (controlled by the choke) and other choke mechanisms to get even thicker. As the engine warms up, the gunk gets thinner and allows for normal operation.

Remember, this is all theory/guesswork off the top of my head. Based on my knowledge of carbourated engines, not FI. But the choke should work basically the same.

1997_LeSabre 02-03-2005 05:09 PM

Yes that is extremely excessive. I have a 97 LeSabre, same Vin K engine as yours. Mine warms up at max 1400 rpms, when it's zero degrees F out here. Your Idle Air Control motor may be sticking, or you could have a vacuum leak, or an intermittently faulty throttle position sensor, or .... any of a thousand other things that can make a fuel injected car do weird things. Do a search on this board for how to check your TPS voltage, should be around 0.040 idle 4.10 wide open, stock. Take the IAC out and clean it with water. If it's really crapped up and/or your car has a lot of miles onit, it wouldn't be a bad idea to get a new IAC. Check all vacuum lines. If you don't have a lot of diagnostic experience with newer cars, get yours over to a shop. You're definitely going to do damage to the engine running it at high rpms when it is just-started cold.

96LeSabre 02-03-2005 05:49 PM

Ok, I was planning on cleaning the throttle body, and I will check out what else I can. Anybody got any opinion on the cleaning of the engine with the seafoam. No one said it was wrong when it was posted before so I'm figuring it's alright, I just wanted to check.

MOS95B 02-03-2005 06:21 PM

The only time I've used SeaFoam, I've just poured it into the tank (or the carb, but that don't apply here). But that doesn't clean all the passages.

I've never done it the other way, so I'll wait for smarter people to chime in...

96LeSabre 02-03-2005 06:25 PM

here's the link so people can get a better idea of what I am speaking of. http://www.geocities.com/rivierareso...ecleaning.html


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