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ghost in the machine

ugabuga

New member
Joined
May 29, 2016
Messages
2
Location
Deltona FL
Corvette
1996 Coupe
Good Morning everyone an Happy Memorial Day Weekend.:beer
I'm new to this forum and I'm looking for help.
Finally my c4 (96) was ready for the weekend! (not relay apparently).
After a major 3 days of work on the Optispark replacement , everything looked fine, engine was running like silk, making all the good noises that one would expect from a health LT1 engine! But last night, after a 50 or so miles drive the engine died while on idle from just a block of my house, it started right after and the died again, this time it was harder to start, but it did and I was able to park my baby in the garage. This morning , after hooking the car to the computer I’ve found 2 codes on stored on the car.
P0102 mass air flow circuitry low frequency and P0372 ICM 24x reference circuit missing pulses.
Now here is the strange part… when the key is on the “ON” position (engine not running) lots of strange noises are happening on the engine bay.
1. the air pump cycles on and off
2. fuel pump cycles on and off
3. noises that sound like an shot circuit of some kind.
Isn’t this curios?
If I clean the codes on the computer they come back (even if the engine is not running)
I’ve unplugged everything from the ignition system and the problem seems to occur only when the optispak harness is plugged in. (harness is in good shape and the terminals are clean.
What could have happened to the optspark to cause this weird problem? (Hope is not the PITA optspark!)
Open for Ideas, Suggestion, Miracles……
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
The optispark receives 12 volts from the Red wire on the four pin connector. It's used by the optical sensor inside the optispark. If you have your old optispark, plug the 4 pin electrical connector into it and turn the ignition On.
Verify the weird noises are gone. If they are it confirms your new optispark is bad.

Below is a picture of what the optical sensor looks like.
 

ugabuga

New member
Joined
May 29, 2016
Messages
2
Location
Deltona FL
Corvette
1996 Coupe
The optispark receives 12 volts from the Red wire on the four pin connector. It's used by the optical sensor inside the optispark. If you have your old optispark, plug the 4 pin electrical connector into it and turn the ignition On.
Verify the weird noises are gone. If they are it confirms your new optispark is bad.

Below is a picture of what the optical sensor looks like.
Thanks for the replay, I'm going to do that today.
 

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