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erratic idle then kills


oldchevy
01-26-2007, 03:30 AM
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
01-26-2007, 08:00 AM
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
02-07-2007, 03:10 AM
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
02-07-2007, 10:45 AM
read the thread " Idle surge" below it might be some help. What model is the truck your working on and what engine?

oldchevy
02-07-2007, 12:59 PM
the idle surge thread it totally different, his was all the time.

2000CAYukon
02-07-2007, 01:19 PM
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
02-08-2007, 03:38 AM
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

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