My car still has a surging idle after replacing the Idle air control valve yesterday but I did notice its only when I have the heat on. The car is an 02 with the ecotec. Any suggestions what to look at it?
Mine turned out to be the timing chain guide being broken at the top. See picture below. My car wouldn't idle correctly but would drive fine otherwise. Sometime would idle ok but fluctuate 50 - 100 rpm's. Sometimes would bounce around between 400 - 1000 rpm's. Most of the time would fluctuate like that by turning the heater on. Sometimes it would die coming to a stop. You can take the valve cover off and with a long screwdriver be able to get to it and you can see it with a flashlight. If it wiggles around then it is broken. If you are lucky like me, then the bolt will be sheared off in the head also. Probably not the news you want to hear but it is something to check and could very well be your problem.
Also, I don't know if you are getting any codes but mine would only throw a PO172 and only after 50 - 80 miles of driving after being cleared. It did throw a PO300 once but never came back again. If you have a standard transmission, my car would buck sometimes when slowing down under 2000 rpm's.
If you can find someone with a good scan tool, you could have them check the status of your sensors to make sure they are giving the right information. I was told everything was working properly when I had mine scanned, which was right. That will rule out the oxygen sensor and other such items that get expensive trying to solve the problem.
Just some things to think about.
Could also be a bad tps....
is youre battery and alternator charging properly? Could have a premature Head gasket or intake gasket leak. Thats will cause a surge issue. Compression test on each cyl will allow the findings to be made.
Okay thanks it did throw a code but all I did was disconnect the battery for a while and it hasn't came back. This morning driving it never did and I drove for about an hour but sometimes when I'm driving you can feel it surge a little so could that be the timing chain guide? Makes sense
Never seen so many off base answers in one post.
