Need some help with ICM, code P0304

[rfortier1796]

My girlfriend's Saturn is running pretty rough, so we pulled the code and got a P0304. Started with the basics, checked the plugs. Cylinders 1-3 were ash white all the way across, so there is some detonation, cylinder four was completely black. Swapped the plugs for some OEM ones, still have the same issue. Based on the best of my research, it looks like the ignition control module problem common to the 2.2 Ecotec.

I've done all the searches, I'm just looking for a good DIY on this part. I hate to say it, but seeing as that it is my girl's car and not mine, I don't want to dive head first in without knowing what I'm doing. That is pretty sad considering the work I've done on other cars. Anyone have a decent walk through on replacing it? It looks to be a straight forward plug and play job, but I want to make sure all I need is just the new ICM (AC Delco part D1968D, ~75 overnighted to us) and nothing else for it. Thanks in advance for any help.

-Robert

[fdryer]

It might help to post year and model.

[rfortier1796]

Originally Posted by fdryer

It might help to post year and model.

2002 L200 with the 2.2L Ecotec.

[fdryer]

You are correct about the icm being problematic and the more likely of the two ignition parts to fail. You can try pulling out all three; plugs, ignition coil pack and icm to lay out on top of the engine, all connected together for a spark test with the plug bases grounded to the engine (use wire if you have to). A simple blip of the starter should confirm spark plug #4 not firing. If I'm not mistaken, the coil pack consists of a pair of coils to fire the four plugs, making the coil pack less likely to fail.