4th Gen 93 LT1 Camaro ICM Trouble

[Sook]

With the 470 ohm resister between your sense and your sorce. Your alternator should put out steady it should not fluctuate. Also if you have a bad ground your alternator will not put out correctly. Did I say check your ground? :-)

On your advice, removed the harness ground from the block, sanded it down, cleaned it with goo, and refastened.

Swapped the MSD plug wires with autozone specials, since that's all I could get today for diagnosis purposes. Got the old wires off, ohm'd them out... suspense... 8 out of 9 were bad (two orders of magnitude low on resistance), and the 9th is questionable at best.

Two of the wires looked like this!
IMG_20160929_212354.jpg

Unfortunately the set I got from autozone was missing the coil wire, so I used the questionable MSD wire for testing on the coil. New coil wire will be here tomorrow for further testing.

Fired up the car and the tach isn't bouncing around any more, getting an occasional wobble that I'm hoping will be fixed by swapping the coil wire. Alternator isn't getting stupidly hot like it used to, ICM is getting hot but I can actually touch it (not at all possible before). I didn't think it was possible for these wires to be bad, could have sworn we changed them this year.

I'll probably try to get a better set of wires for TWS, swap the ICM just in case and bring a spare. I'm not 100% sure this solved my problem, but fingers are crossed. Seems like we're always finding more things broken on the car, and fixing them just creates more problems.

- Josh

[GlennCMC70]

While the harness ground is important, you also need a block to chassis ground.
I also recall a ground strap from the ICM to the chassis.

Also still have the finned heat sink under the ICM?

[Supercharged111]

Aren't MSD wires lower resistance by nature anyway? That totally screws with your non-adjustable dwell which is why I run factory wires. That and factory wires aren't all the same length like that Autozone garbage. I also want to footsomp Glenn's input. Someone else asked about thermal compound and I may have skimmed too quickly but don't recall an answer.

[Pranav]

FYI I checked yesterday, and my alternator does make a tiny bit of noise with the engine off and the ignition switch on. Has been that way for a long time but it's quiet enough for me to have to try listen for it.

Yeah I found a bad plug wire last weekend; stuff happens.

Look into the heat protective fiber wraps if you're burning them up. I made all of my own MSD wires with these ends:

https://www.summitracing.com/parts/msd-3325

The opti and coil uses these:
https://www.summitracing.com/parts/msd-3304

I run the #7 wire under/behind the motor mount bracket (with a zip tie holding it there) and have it come towards the plug from the back. It actually is the only one of my plug wires that gets a wrap as it is still close to the exhaust:
https://www.summitracing.com/parts/the-14262

If you're interested I have a box full used plug wires, mostly MSD.

[BryanL]

On your advice, removed the harness ground from the block, sanded it down, cleaned it with goo, and refastened.

Swapped the MSD plug wires with autozone specials, since that's all I could get today for diagnosis purposes. Got the old wires off, ohm'd them out... suspense... 8 out of 9 were bad (two orders of magnitude low on resistance), and the 9th is questionable at best.

Two of the wires looked like this!
IMG_20160929_212354.jpg

Unfortunately the set I got from autozone was missing the coil wire, so I used the questionable MSD wire for testing on the coil. New coil wire will be here tomorrow for further testing.

Fired up the car and the tach isn't bouncing around any more, getting an occasional wobble that I'm hoping will be fixed by swapping the coil wire. Alternator isn't getting stupidly hot like it used to, ICM is getting hot but I can actually touch it (not at all possible before). I didn't think it was possible for these wires to be bad, could have sworn we changed them this year.

I'll probably try to get a better set of wires for TWS, swap the ICM just in case and bring a spare. I'm not 100% sure this solved my problem, but fingers are crossed. Seems like we're always finding more things broken on the car, and fixing them just creates more problems.

- Josh

Another guy missing a pinky??? What's going on in CMC. Al says those wires look great you just need to cross them.

[Sook]

While the harness ground is important, you also need a block to chassis ground.
I also recall a ground strap from the ICM to the chassis.

Also still have the finned heat sink under the ICM?

Ground strap is present, heat sink is still there with thermal compound. The ICM is bolted directly to the head without a ground strap.

I fired up the car from cold today and it seems to be dropping spark and surging until it got some heat in it. Still was running like crap and O2s are all over the place. Revved the engine a bit and it smoothed out mostly. Tach is still slightly noisy, but much better than before.

I don't have a high confidence that the car is going to make it through TWS weekend... Getting pretty f'n sick of LT1s