For a couple months I've battled a WOT 5500rpm miss. Well this past week its turned into an all range misfire just cruising around. Its accelerates, just not smoothly and lacks power. NO SES LIGHTS. Nothing has been touched other than swapping out coils. All wiring is intact and nothing is unplugged. Wires are less than a year old and tucked away, but new wires are on the way as I type this. Coil wire is good as well and snug on the coil and opti.

Before I dig out the Optispark, and install those new wires that are on the way, is there any chance this is an ICM problem?

Ive done a bunch of searches and it seems to be a 50/50 issue with a bad ICM setting a code if it is indeed bad and/or a no start issue -OR- a weird range misfire driveability issue like I have, but no one ever responds with the actual fix to their problem.

Yes I get the ICM can be tested, but no one around here can do that. I went to 2 Autozones and they lack the multi-meter. And the ICM needs to be hot. Well, by the time I might even be able to get it tested, it could cool off and a false negative test would be done.

Luckily, the car isn't dying on me if it is the ICM, but again before I spend $120 on a GM ICM, does this sound like an ICM problem?

 

Went to autozone and scanned for codes. Got code 48 and 72. Im betting the 48 is when i unplugged it and drove around for a couple miles trying to see if it would run better.

Code 72 (VSS Loss) has me stumped. I searched and usually it won't shift right or the speedo won't work. My shifting is fine and the speedo is working fine as well.

If I have an opti problem or o2 problem wouldn't it first set off an SES light and 2nd, wouldn't it drive fine in open loop then turn to crap in closed loop? Its running like crap all the time now.

 

The codes for the optical cam position sensor in the Opti do not turn on the SES light.

The VSS wire may be loose and lost contact for a few seconds. That will set a stored code.

You can heat the ICM with a hot air gun to test it.