Backstory: I have a 2002 Cavalier with the 2.2 ecotec engine. A while back it lost power and was only running on two cylinders. I pretty much knew it was ignition related so I removed the coil-pack on top of the engine and removed the plugs for inspection. Two of the four plugs were worn so badly that they couldn't fire. There wasn't much left for the electrode to spark to, unless it was sparking to the top of the piston. I couldn't believe the car was even running with these plugs. With only $100 in my hand I purchased 4 new plugs and a new after market coil-pack to be on the safe side. I decided to use my old ICM. One of the new plugs was improperly gapped so in an attempt to get the gap in tolerance, I accidentally broke off the very tip of the electrode. I bent the cathode back in tolerance and "went with it". The car fired right up and ran perfect.... for about 2 months. Now I have a mystery.
The car runs fine while cruising above 1000 rpms but as soon as you come to a stop it starts missing and stumbling. It idles a bit low though and has an occasional miss. It gets worse if the cooling fan is on or the A/C. When the fan kicks on the car immediately stumbles and all the lights go dim as if the battery was low. I'm thinking that its only due to the 400-500 idle the car currently has, added with the random miss fire or stumble.
I just knew this problem was the ICM because that was the only thing I didn't replace and many places I searched online said this is the most common cause of miss fires and P300 codes. I bought a new "cheap" ICM that didn't fix my issue. Swapping my coil-pack out with the old one didn't change anything. Swapping out the ICM with the old one didn't change anything either. I thought it might be that one plug that I broke so I bought 4 more new plugs and installed them which still didn't change anything. This leads me to believe that the only thing my car needed was spark plugs in the first place, and maybe this is true. I have searched everywhere on many forums and elsewhere and found only 1 youtube video that shows a car like mine doing the exact same thing and they said it was the MAP sensor. I have one on order but I'm not thinking that is my problem either because:
Old coilpack with new ICM gives me best results. Still misses and stumbles but not as bad as other combinations.
New coilpack with old OR new ICM (don't matter) stumbles worse, misses more at idle
Old coilpack with old ICM is better but not as good as what the new ICM does.
The old parts are original equipment, the new parts are aftermarket and weird named.
If my MAP was bad, why all the variation with the different ignition components? Unless someone has a different idea I'm going to install the MAP and see what that does and if that don't work I may try to find O.E. Coils and ICM.
Some of the variation in the ignition components may be due to the plug boots not being shoved up against the coils completely. I'm hoping that it was just my error because if so it puts more burden on the MAP being the culprit.
https://www.youtube.com/watch?v=WOv2vXeKc4Q at the 0.33 mark you can see a little dip in the rpms. My car does this "dip" every 4 or 5 seconds.
I'm doubting it jumped time or my cat is clogged as I have experience with these issues on other vehicles. While searching for vacuum leaks nothing was discovered. Anything else thinking MAP sensor?
