Runaway car

I have 2001 Chevy Venture van. Most of the time I start it up, especially when it is 45 degrees or colder, and it races about 2,000 to 3,000 RPM.

Usually I let it race in neutral so as not to burn the clutches in my transmission by holding my foot on the brake, and in about 3 minutes I turn it off and restart it, and it idles normally. But sometimes it continues to race, only a little slower. Even when it is at normal operating temp it does this and I can’t get it to idle normally.

And another thing, when it is acting like this, it won’t downgear on the road. I can put my foot to the floor and it just crawls up hill until I manually downgear.

Does anybody have ideas. My mechanic has cleaned everything there is to clean, throttle control sensor replaced, another sensor at the big intake pipe replaced.

Have your mechanic check the signal for the coolant temp sensor for the computer.


It is interesting that you suggest this. Because ever since I owned the van, the temp has been acting unusual. When I am out for a ride on Sunday afternoon, looking at houses, I go very slow and sometimes up steep hills. The temp goes from 1/3rd to 2/3rds hotter. And it fluctuates up and down. It seems too sensitive. Otherwise I would have no idea why you suggest I look at a temp related issue to solve a fast idling engine problem.

The computer uses the temperature the CTS (Coolant Temp Sensor) is reporting to determine such things like fuel load and idle speed. If it thinks the engine is too cool, it will bump up the injector pulse width to enrich the fuel mix, like the old cars did with a choke. It will also bump up the idle to help keep the cold engine idling, just like the choke function on old carbureted engine. But, if the CTS is erronously reporting the temperature as to cool, the computer knows no different, and gives you the results your complaining about.

I hope that helps.

Always check for TSB’s with these type of concerns. It sure doesn’t pay to be doing your own diagnosis when its already been done for you.

What type of scanner does your mechanic have. This may take advanced OBD2 diagnostic capabilities to figure out does your mechanic have them?