SteveR

A few minutes after my car gets to operating temp, it starts misfiring, the longer it runs the worse the problem gets. Eventually it will just die. It is setting DTC #42 - "Ignition Control (IC) Circuit (Shorted or Grounded Circuit)", but usually won't turn on the SES light until it is running so bad it is about to die. It is definately an ignition problem, I can hear the unburnt fuel exploding in the exhaust. It is not the coil or ICM. I checked for power on pins A & D, they both have 12v even when the car is hot.

http://home.comcast.net/~fastbird/Tr...ds/dtc43p1.jpg
http://home.comcast.net/~fastbird/Tr...Aids/dtc42.jpg

The ground is flaky (pin C), I measured 180ohms to the battery ground when the car is hot, and near zero after it cooled off. I think that may be my problem...but I don't know where the ground wire from the ICM (pin C) attaches to a ground point. It goes towards the back of the engine over the intake manifold, directly behind the coil. Does anyone have any pictures of the back of the engine when it ISN'T in a car? I can figure out where the wire goes, but it will be a pain.

Any ideas or tips? Anyone have this problem before and solved it easily? Thanks for any information!

SoloExceptional

http://shbox.com/1/g103.jpg PCM to Block Ground
http://shbox.com/1/95_ign_system_schematic.jpg The ground goes to the block from the ICM above the starter if I remember correctly


Thx Shoebox

SteveR

Great. Thanks, I'll pull that off and clean it up tomorrow. Its ridiculous the amount of information you can find on this forum.

Any more input would be appreciated.

In this picture:
http://shbox.com/1/harness.htm
I'm trying to verify that the path for the ground wire from the ICM connector is good. I'm guessing somewhere in the harness, there is a splice where the engine block ground, coil wire grounds, and all other grounds come together. Can anyone confirm this and maybe tell me where in the harness that splice might be?
ICM connector: http://shbox.com/1/harness7.jpg

Anyone think I'm completely chasing the wrong problem?

SteveR

I checked the ground wires last night and didn't get anywhere. Any suggestions? I'm wondering if the opti could cause this, although I don't exactly see how. When it is cool, it will rev to the redline. Once it gets warm, it won't make it above 5,000, and misfires really bad below that. Could it be a fuel pressure problem? I don't exactly see why heat would aggravate that though.

SoloExceptional

Bad O2 Sensors perhaps? that's what happened to mine, was fine till it got warm then it ran like crap because it was running ultrarich

SteveR

Did it set an O2 code?

SoloExceptional

No, ironically, mine never did.. It just ran like crap.. I replaced them, it runs great..

SteveR

Would the problem eventually get so bad that the car would die? Mine just isn't driveable after about 15 minutes of city driving. How did you figure out that your O2s were the problem?

Thanks for the help!

SoloExceptional

Replaced every sensor on the car one by one, and when nothing helped I resorted to the O2's and when I got under the car I had found that my connector to the PCM on the passenger side had melted to my header *doh* had to purchase a new connector and O2, but you can unhook the O2's and run the car, if it runs good, plug them in 1 by 1 and see when you car starts running like crap.