Bad backfire at idle and P1361

[vipergtx500]

I was driving through a drive-through the other day when my car suddenly started to backfire every couple seconds. This only happened at idle, when i got on the gas it seemed like i went away. I drove straight home, about 20min, performance seemed the same, but I could've just been telling myself that. I scanned the car when I got home and besides the P0430 code "Catalyst System Efficiency Below Threshold (Bank 2)" that has been there for months now, it read P1361 - "Ignition Control (IC) Circuit Low Voltage". I have checked almost every forum and I have yet to find a straight answer on how someone's fixed this issue. I've found everything from replacing the coil and ICM, to replacing the opti. I replaced both the ICM and the coil last january, as well as the distributor portion of my opti, which I'd hate to think went again. I just wanted to see if anyone had any ideas before I start replacing everything again. thanx

[sweetbmxrider]

you could check the harness coming off of the opti for corrosion or contamination. you can also inspect the icm ground on the cylinder head. make sure its tight and clean. you could space the coil off of the cylinder head with a few washers, sometimes they heat up and will cause issues. you should also reapply dielectric compound between the icm and its bracket.

also, its telling me that this code sets during cranking. "The PCM detects 84 crankshaft revolutions without any IC activity during cranking."i would clear it and see if/when it resets.

[vipergtx500]

cleared the code and it never happened again, thanx for the advice

[vipergtx500]

strike that, happened again, replaced the icm and spaced it off the head, also replaced the IAC. Still the same problem at idle, no code this time.

[Pampered-Z]

link below details how to check out the igm module.

http://www.camaroz28.com/forums/showthread.php?t=601565

Couple other things:

Check the coil wire as well. They tend to corrode and cause issues. you can also try running a seperate ground wire from the coil mount to the frame grounding point. I chased the same problem on my car for months, sent the excel ign system back twice, added a second ground and never saw the issue again.

[S.J.SLEEPER]

did you look for a coolant or oil leak?
if you have a leak... maybe leaking into the dreaded opti.

I take it its a lt1....I have seen many ecm's go bad in them causing random misfire intermittinly and drive fine under acceleration or misfire while lugging the car in a like 5th or 6th.

[vipergtx500]

I'm going to get a multimeter and check out the icm and coil connections. For the ground wire, you want me to put an extra wire where all the ground straps are on the coil/icm assembly and ground it to the block? Just clarifying not sure on the locations.

I have not noticed anything leaking on the opti although ill check again to be sure.