97 sunfire low/rough idle

[bigx1384]

my 97 sunfire has a low/rough idle. car runs fine otherwise. when cold it starts right up, idles about 1100rpm, then slowly idles down to around 600 rpm. when i pull up to a stop, it idles rough. i can tap the gas pedal and it will idle smoother. i have replaced the intake and tb gaskets, cleaned the tb, replaced the iac, tp, plugs, both o2 sensors, checked for airleaks, cant find any. help.

[bigx1384]

it is a 2.2 automatic with 150k miles

[302Z28]

My '97 Cav had a similar problem. After 4 different shops worked on the car, including the local Chevy dealership and changing almost every sensor on the car, someone suggested a plugged cat convertor. I had 3 shops check the convertor and all said it was fine. They all said that a plugged convertor will not cause an idle problem, but the issue will be at higher RPM's. Two shops used an infared thermometer to measure the input and output temp of the convertor. The third shop inserted a pressure gage in the -02 port. Finally, a shop installed a gage in front of and behind the convertor and noted the pressure difference. They said the convertor was partially plugged and replaced it. It idles and runs like a new car. Any compentant exhaust shop should be able to check the convertor - free of charge.

[Spyder3K]

What about changing the MAP sensor or making sure the IAT sensor is working right?

That map sensor can be a biatch. Trust me, mine hated me for a while (2.4L DOHC).

I'd check to see what the voltage is off the MAP and compare it to GM data if you haven't done so already.

I also wonder if it's cuz your Valve cover is leaking. I just did cam work on my car and everything's panned out once the seals were fixed on them. I'd look at your valve cover and see if it's got oil leaks and for the hell of it, if you're going to keep your Sunfire long, I'd replace it. It's easy to do it. I'd love to have it that easy with my car haha.

[bigx1384]

ok. did a compression check, had low comp on 2 & 3. 110psi. pulled the head off, had burnt exhaust valves. did a valve job, put it back together, still rough idle. but it does run MUCH better at road speeds, has alot of get up and go. gonna try the map sensor now.

[bigx1384]

replaced map sensor, still no difference. sold the car.

[muff34]

Originally Posted by bigx1384

replaced map sensor, still no difference. sold the car.

lol............ outta sight outta mind .