I have a 2001 1.8T AWM. I had a slight clicking noise that you really had to listen for to hear. So I had a coworker who's a mechanic take a look at it. He started disconnecting my coils to see if one wasn't firing. Turns out the #1 (front) cylinder wasn't firing. We tried swapping the coils in #1 and #2 and the problem stayed in #1. So we just figured it was a fouled plug and I was just going to replace it. Well a couple minutes after we did that I started it back up and it was knocking, shaking real bad, and threw a CEL. The CEL started flashing as well. We got it scanned and it had #1 missfiring as well as a P0351 (something about coil A primary/secondary circuit malfunction.) I have since replaced the plug and coil and the problem is still there.

I have been searching and found that it might be the ignition control module. But I'm not sure if mine has one. ECSTuning doesn't have one for my engine (they seem to stop in 99 except for the AEB motors.) So do I have one? If not what else could the problem be? And please don't tell me it's the wiring harness because I'm sure that would cost a fortune to fix.

 

have you checked for vacuum leaks? Maybe a dirty injector?

 

I'll check that today. Is it easy to swap injectors to see if one is bad?

 

kextyn, you don't have an ICM. P0351 indicates a bad ignition coil
for cylinder 1. Try swapping coils 1 and 4 to see.if the code changes
to P0354. Let us know how many miles you have.

 

I have already replaced the coil with a brand new one and tried swapping with #2. Does it make a difference if I swap it with 2 or 4? The problem stayed in #1 when I did that though. I'm at about 65000 miles.

 

Problem solved. It turned out to be the #3 pin on the connector for coil A. This is the wire from the ECU that tells the coil when to fire. The wire was broken inside the connector. By pulling the connector off while trying to diagnose the original sound it completely broke free and that's why the engine went to crap afterwards. Before that it was still intermittent though. I only know this because the engine idles so smooth now compared to any time I can remember in the last 6-12 months. I'm guessing the problem started the last time I replaced my plugs. It's so nice to be running on all 4 cylinders all the time now. I don't feel any vibration from the engine at idle anymore...used to be quite prevalent in the wheel and shifter.

 

Congrats, nice that you found this.
I bet you are enjoying the nice snooth ride now.