Hi this is my first post on the forums and I really need some help. I have a 2003 Chevy cavalier with a 2.2 L61 engine. This is going to be a long post explain my problem the best i can. The car has a hesitation, misfire, rough/unstable idle and stalls at idle but will refire imediately. At idle the engine will rev between 500 rpms and over a 1000rpms. Also when let sit over night the car will not stat unless i step on the gas and as soon as i let off the gas it stumbles and stalls. If i let it warm up for a min or 2 holding the rpms at around a 1000 it is drivable but the idle will stumble and stall. The problems mainly happen after running thru a puddle or during a heavy rain or wet slushy snow. The car has/had a P0507 P0171 P0300 and P0440 codes but not all at the same time. It was worse after i got gas at a meijers gas station.
OK now onto what i have already done. As i stated above i though maybe i got bad gas or a high level of ethanol. But i drained the tank and put fresh gas in it and put GM fuel system cleaner in the tank. The fuel tested 10.06 percent ethanol which i was told was ok by gm specs. I flushed out the fuel injectors with gm top engine cleaner and replaced the fuel filter. The fuel press stays at 58 psi and only drops around 8-10 psi over a period of an hr. The fuel pump has been replaced with a gm pump 20k miles ago.I replaced the air filter and IAC valve. I removed the throttlebody and throughly cleaned it and the iac passages.I clean the engine ground for the ignition and pcm. I also check for vaccum leaks but could not find any. I pulled the 2 plugs closest the timing chain and they appeared to be ok just a lil bit wet and were dark colored around the threads but the electrode was white. ALso the trac off light comes on and stays on. I have access to a tech 2 and here are some of the specs i got while running at idle.
Barometric pressure-99kpa
MAP-10.0-2.5 volts and 25-35 kpa
O2 sensors front-10-850mv rear 200-900mv
CKP sensor - 10-250 counts
Injector pulse 3mv at idle-6 when revved to 1500rpm
Short term fuel trim -3 to 3
Long term fuel trim 18-21
misfire on all 4 cylinders- 1-4 counts on all cylinders at different intervals(random) at idle or when letting off the accelerator..no misfires while under load.
TP sensor .5 volts at idle
Ignition voltage 11.9 volts with key on and 14.7 while engine is running
Knock retard is 0 degrees
Battery tested good
I reset the fuel trim data after doing the fuel system test and unplugged the front o2 sensor to bring the car into open loop and it ran slightly better. I drove the car home and let it sit in the garage for 2 days then started it and it ran like normal idled perfect and no misfires or surging or stalling. I drove the car for a week and it ran great i thought i fixed it. No check engine lights. I took the car thru a car wash and boom same problems came back. It stalled 3 times and would not idle properly and i could tell it was misfiring and the check engine light came back on. I will check the codes tomorrow but im at witts end with this car i dont want to throw parts at it. Im thinking possible ignition module but not entirely sure because it mainly happens when its cold and wet. Any help would be greatly appreciated and again sry for the long post but i gave as much detail as i could.
Thanks Greg
I have a 2.4 so not sure I know if you have a distributor or not on your engine. If you do check the cap for water condensation.
I know I am going to look like a dummy if it doesn't have a distributor. Water is not good to spray on the engine or up under the engine as a rule at a car wash. I hope some one else can help you with a possible water condensation problem in your ignition system. Sounds like your fuel system should be good.
71k miles. Now it runs perfect after sitting for a day or 2. I checked the plugs, 1and 4 looked wet and 2 and 3 were clean. All 4 plugs were bright white around the electrode. The coil pack looked good. All the sensors on the tech 2 were with gm specs and working. I tried spraying the wiring with a salt water spray to see if i could duplicate the problem and i could not find a problem.
