M42 coil fault code, not firing on #2

[mbradican]

My '95 Ti started running on three cylinders two days ago. I took out the plugs and they looked OK, but Number 2 looked damp. I took off that plug wire and the engine ran the same, so I assumed it wasn't firing. I checked for spark with a screwdriver and it sparked. The check engine light hadn't come on, but after I put in new plugs to try it again, it ran the same and the check engine light came on with fault code 37 (OBDI) for coil pack. I did a compression check and the other three were 175-185, but number 2 was 210. I thought maybe the coil was weak and I had carbon build-up. I bought a new Bosch coil pack and installed that, but it is still running the same. The plugs are new, the wires about two years old. I checked the plug wire on #2 for continuity and it seems good. I'm stumped now.

[mbradican]

I did a stomp test this morning and came up with multiple 1271 codes, for coil. The 37 code I got from my Bav Auto scanner. The coil is brand new; what else could cause this code? I started it again this morning and used a timing light. I got a signal on spark plug wire #2, but removing the wire from the plug did not change the way the engine ran. I check for a signal on plug wire 4 and got none, so I disconnected that one and now I know it's not firing either. I think it's amazing it can idle on two cylinders. I guess the next thing is to pull the DME out and look at it.

[bazar01]

Originally Posted by mbradican

My '95 Ti started running on three cylinders two days ago. I took out the plugs and they looked OK, but Number 2 looked damp. I took off that plug wire and the engine ran the same, so I assumed it wasn't firing. I checked for spark with a screwdriver and it sparked. The check engine light hadn't come on, but after I put in new plugs to try it again, it ran the same and the check engine light came on with fault code 37 (OBDI) for coil pack. I did a compression check and the other three were 175-185, but number 2 was 210. I thought maybe the coil was weak and I had carbon build-up. I bought a new Bosch coil pack and installed that, but it is still running the same. The plugs are new, the wires about two years old. I checked the plug wire on #2 for continuity and it seems good. I'm stumped now.

Did ou see any traces of motor oil on the spark plug holes? I had the same issue on misfires and m spark plugs were soaked in motor oil due to leaking valve cover/spark plug seals.
If that is not it. it could be missing fuel on that cylinder because there was spark on the plug.
Have you checked that the injector was firing? If it is firing, it could be plugged up. Try tapping lightly on the injector.

[mbradican]

Thanks, but no oil in the spark plug wells. I changed the valve cover gasket about a year ago. I haven't checked the injectors yet. I took out the DME on the theory that it is not sending spark/power to the coil. There is no spark at all on #4. #3 shows some spark with a timing light, but it's not firing. I'm looking for a diagram showing the DME connector pin layout so I can see if there's a broken wire in that loom that goes from the DME to the coil.