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Re: 1992 Vette Misfiring intermittently

Subject: Re: 1992 Vette Misfiring intermittently
by bogus on 2020/4/30 18:32:09

The C41 is worrisome to me.

That is the signal that goes from the engine controller to the chassis controller...

I think I know what is happening... but I am not sure and it would take a laptop to track it with software to monitor and record things. This would also require a USB connector to allow for communications to work.

I think Tunercat is the software you want, I will have to confirm, it's been a while.

However, it sounds like to me the ECM is shutting down or failing. I like the idea of making sure everything is connected and clean. Make sure the grounds are clean and that the power block (behind the battery, against the fire wall) is clean and all connections are solid.

There are many places where things can be corroded, especially near and under the battery.

Do all that minor stuff and then remove the plate on the bottom of the engine controller. Take a sniff. Does it smell like burnt electronics? If not, that's a good thing. If so, could be bad.

Take the controller and put it back, but don't put the cover on it. Get a can of air, like used on computers to clean dust off. Take the car for a drive, once it starts to misfire, pull over, flip over the controller, invert that can and spray the cold gas into the controller. If it starts running better, you have found the problem.

Other sources of this problem are a bad coil and/or ICM - Ignition Control Module. Also, a bad harness at the ICM will wreck havoc on things.

The ICM is on the right head. You can see the coil wire. This is the source of the spark.

If the engine controller seems ok, the next time it misfires, use the same spray on the coil/ICM. If things settle back down, there is the problem.

I am betting more on the coil/ICM vs the ECM.

If it is the ECM, unless things have changed, you will need to go used. 1992 and 1993 Corvettes share the same ECM. 1993 Camaro and Firebirds, with LT1, share it, too. And from my initial search, no love new... no one is remanufacturing these things.

Again, I would start with the ICM and coil. Depending on mileage, that would be a great starting point. I am guessing the car has over 100k, so yes, ICM and coil.

And don't be surprised it is the harness. They get greasy and rotten and stuff. It ain't pretty... Same goes for the harness to the opti itself.

touch base before buying anything. There are some upgrades you need to consider.


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