Is there anything besides the coil, coil module, or opti that could cause a loss of spark? My friends 93 Vette (LT1) has a severe stumble upon acceleration (moreso after it is at operating temp). He's checked the fire and the plug wires have to be within 1/4 inch of the plugs before it will jump and he said it doesn't look like a strong spark then.
So far he has put a new opti on, changed back to an old coil, and borrowed another module, none of which have helped or fixed the problem. He ran a datalog on it today but didn't see anything out of the ordinary.
The car does has a 6AL box and he disconnected it, but it ran even worse after doing so.
All ideas are welcome.

Thanks,
Chad

 

Burnt/old plug wires could cause it.

 

Forgot to add that plugs and wires are new as well.

 

I chased down a weak spark to a bad coil. I realize you guys tried swapping in the old coil, that doesn't necessarily mean it's a good coil!

 

opti is always something to consider. but a fuel system problem is something to think about as well.

 

I had a bad stumble that turned out to be a clogged cat.

 

Trying another coil is what I plan to try next. Probably start looking at the fuel after that.
What are the odds of the PCM going bad or not sending enough voltage to the coil or coil module?
Is there a way to check this?
I have 2 96 cars and an 02 so the speed density cars are new to me.

Thanks and keep the ideas coming.
Chad

 

speed densitiy isn;t that much different. I know other then injector conrol etc etc, the main diference is the non use of the MAF. instaed the cimputer relies on MAP and IAT signals for fuel control.

As far as the pcm. the opti gives the PCM the info it needs to send the signal through the white IC wire to the module for spark timing. you should be seeing verying voltage while cranking at the white wire if it;s good.

but usualy the first things to cause this trouble is opti, coil, plugs, wires, fuel system. ICM's usulay give out after a heat soak and an opti can act the same.

you can always run a ohm test on the coil. auto zone can "test" am ICM but I don;t compleatly trust that. fuel system is really easy to test so thats where I always start, that and it's so picky on things like fuel pressure that it's never bad to test first