erratic idle then kills

[oldchevy]

hey all.

I've been having this problem for about a year now and now that it's cold it's finally bad. Once i start the truck (cold start only), the idle surges up and down a bit and if I don't let it warm up, it kills when I put it into gear (reverse).

It doesn't kill if i don't put it into gear, and once it's warm there are no issues.

I've done all of the obvious, temp sensor, plugs, caps, IAC etc. No vacume leaks that I can find. I did use teflon tape on the temp sensor..which i believe is not good..do you think that could create this much of a problem. I only have this problem when the weather is below 60 degrees or so. Also the temp sensor is aftermarket.

let me know if anyone has any other ideas.

[jocat54]

Teflon tape on the temp sensor is not good, sensor will send erratic readings, not sure if would cause the problems you are having. I would pull the sensor out and clean the threads up real good (sensor and block) and put it back to see if anything changes.

[oldchevy]

does anyone else have an idea about this cold engine surging idle? No issue when warm. Only at cold start-up after sittng for 6-8 hours.

[bracketshark]

read the thread " Idle surge" below it might be some help. What model is the truck your working on and what engine?

[oldchevy]

the idle surge thread it totally different, his was all the time.

[2000CAYukon]

Originally Posted by oldchevy

the idle surge thread it totally different, his was all the time.

Yes his was all the time; however, you should still check the egr valve and gasket. Perhaps when yours get warm, the leak seals due to heat and expansion.

Does the EGR hold a vacuum when cold? Does the MAP hold a vacuum when cold? Check the hoses carefully. On mine, the MAP vacuum hose would not hold a vacuum and I had a surging idle.

Tape on the sensor should not be an issue since the sensor is a 2 wire sensor. The tape is not needed since they usually come with thread sealant already on the threads.

//2000CAYukon

[oldchevy]

thanks yukon,

the egr seems to be holding. I'm going to check out the map hoses etc. I read one of your other posts about that. I have a day off monday, im gonna check it out. I let you know what happens.

g