QuestionI have a 1995 Chevrolet C1500 truck (5.0/305, 314k miles, automatic). Let me give a description of what it's doing and what I've done to it.
In the morning when I start it and let it warm up, sometimes it cuts out and dies. When that happens, sometimes it starts right back up and other times it takes up to 10 minutes to start again (the engine always turns over, but just doesn't start). See? Very random...
Other times while driving down the road it cuts outs, misfires, and occasionally (although very rarely) it dies the same as when idling. Also, when it cuts out while driving I can watch the RPM gauge jump around wildly, not sure if that can help diagnose the problem.
What I have done includes:
-checked plugs/wires (OK)
-changed ignition coil
-changed fuel filter
-changed dist. cap and rotor
-new air filter
-added Heet with fill-ups
-added fuel injector cleaner with fill-ups
None of the above helped. So a friend of mine plugged in his comp to check the codes on it. It pointed to the Fuel Pump Relay, so I changed it. But it continues to do the same things and nothing "wrong" is showing up on the computer.
I can't imagine it would be the timing, because it's not consistent at all. I've had timing problems with this truck before and that was nothing like what it is doing now.
Not sure what else to do...
Thanks for any help.
AnswerHi,
I imagine when you said you had timing problems you had a cracked reluctor ring in the distributor and needed a new distributor? sounds like you have a bad ICM that is breaking down at certain temperatures. ESPECIALLY because of the wild tach.
The ICM receives a 4x signal from distributor pickup for ignition control while cranking and ICM sens a 4x signal to pcm and receives a 4x IC control (electronic spark timing) signal from the PCM for timing control. The instrumentation IC uses the ignition signal reference for tach placement. When the ICM is going wonkey its screwing up the EST signal as well. I would replace the ICM module.
Wayne
