The car has progressively gotten worse over the past week with the cold idle. When i start it up after not driving it for a while it has a BAD misfire until the car starts to warm up, and once it is warmed up the misfire goes away and the car acts normal and has plenty of power. Once the car warms up the car will idle fine at about 850, and then sometimes the idle will bounce up to around 1500 and then either stay around there or settle back down. I checked the temp sensor at the sensor and at the pcm and it seemed to be in good working order. The car has no egr so that cant be the problem. I also swapped out the air regulator on the bottom of the intake manifold last week and that did not help any. I have checked the plugs after driving the car and they look very clean but after letting it do a cold warm up i checked the spark plugs and they were fouled with fuel. All of the plugs are gapped to .44. I have searched around and havent found anyone with a similar problem to this yet and since i am only on a break at school i dont have much time to do more research. Thanks

So i pulled the codes and i had a code for the coolant temperature circuit and the knock sensor. I removed the knock sensor and it was cracked and so i swapped it with a spare one i had. I also checked the coolant temp circuit and everything seemed to be fine so im not sure what that code was caused by. The car still started all crazy right after that but in the evening when i started it again and every time since it has been starting fine and feels like it pulls harder now. Has anyone ever had a knock sensor cause a problem like this?

The car has progressively gotten worse over the past week with the cold idle. When i start it up after not driving it for a while it has a BAD misfire until the car starts to warm up, and once it is warmed up the misfire goes away and the car acts normal and has plenty of power. Once the car warms up the car will idle fine at about 850, and then sometimes the idle will bounce up to around 1500 and then either stay around there or settle back down. I checked the temp sensor at the sensor and at the pcm and it seemed to be in good working order. The car has no egr so that cant be the problem. I also swapped out the air regulator on the bottom of the intake manifold last week and that did not help any. I have checked the plugs after driving the car and they look very clean but after letting it do a cold warm up i checked the spark plugs and they were fouled with fuel. All of the plugs are gapped to .44. I have searched around and havent found anyone with a similar problem to this yet and since i am only on a break at school i dont have much time to do more research. Thanks

u should be using bkr7's or 8's gapped at .28.pressure test ur system and try either cleaning the ect or replacing her with an oem dealer unit..go over the little things like adjusting the tps/checking the voltage on the maf/o2 sensor voltage to help u clear someof those symptoms up..also if its a jwt ecu then its pretty normal.I had the same cold start issues but after replacing the ect with a dealer one instead of the borg-warner unit the cold idle seems fine now.be sure to zip tie all of the vac lines as well:biggthump

u might wanna post ur set up just to shoot u in a str8 line:D

Its an all motor setup with s3 cams, header, place racing cold air intake, thermoblock spacers, underdrive pulleys. 8.5 pound flywheel. From what ive read i dont need to go that small of a gap on an all motor setup. I set the tps voltage only a few months ago but i guess it wouldnt hurt to double check that. The car has fairly consistant compression across all 4 cylinders too. Also it is a stock ecu.

I would brush off the o2 and check the wiring on the coolant temp sensor and knock sensor.

My car had horrible problems with the knock sensor. Come to find out, there were about 5 shorts in the 1 knock sensor wire.

The o2 sensor does nothing until the car has warmed up so that cant be the problem as far as the cold start goes. After i swapped the knock sensor out with my other one the car felt like it woke up a lot, but i do still need to check and see if there is a code for that sensor anymore. I tested the coolant temp sensor at the computer and it seemed to be outputting the right readings to the computer. I would figure that if the sensor was bad it would be bad more than just up to a certain temperature....or maybe i am wrong.

My car had a miss fire when cold that would go away when it warmed up. did this for a week, then my headgasket blew. i think in the morning when it is cold, fluid would leak into the cylinder upon intial start up. As the motor got warmer, the leak sealed off and car would run better.

Do a compression check while are is cold, and when car is hot.

I checked the compression i think cold not too long ago but i will check it again. Also it seems that when i wiggle the TPS sensor sometimes i can get it to start acting more normal.