OK, I've been chasing this problem for a while now and am at my wits end. At first it started out as an intermittent hesitation. I would be driving at cruising speed and I could feel it stumble every once in a while. I replaced the coil wire with an MSD wire (already have MSD plug wires), but it made no difference. It then progressed into the car cutting off while driving. After stalling, it would be hard to start, sometimes requiring me to wait a little while. After this I replaced the original coil with an MSD. The stalling became less frequent, but still occurred and the car would usually fire right up. It has now gotten to the point where it won''t start at all. I replaced the ignition control module yesterday, cleaned up the heatsink, and lubed both sides of it with fresh di-electric grease. It still won't start. I wanted to get opinions before I spend the cash on a new Optispark (40K miles on rebuilt motor and 2nd Optispark).

Any thoughts?

Engine Mods are -
LT4 Heads
LT4 Hotcam
LT4 Extreme Duty Timing Chain
GMPP 1.6 RR's
K&N FIPK
Thunder Racing MAF ends
BBK 52mm TB
Jet-Hot coated Hooker LT's, 4" Mufflex ORP, SLP "TOTL" Exhaust
NGK-TR55's, MSD 8.5 mm wires
OBD-I Conversion
Meziere Water Pump
March Underdrive Pullies

 

Have you check the fuel pressure?

 

Yes, fuel pressure gauge on the a-pillar shows 40 psi.

 

Looks like you are suspicous of ignition. Are you getting a constant, healthy spark from the coil? At plugs?

 

I am leaning towards the opti. Plugs, coil wire, ICM, and coil were replaced fairly recently. I'm going to perform the opti signal test on Shoebox's website before I take the plunge though...

 

Good idea before taking on the opti replacement cost and time, if it's not the cause. Good luck.

 

I just battled with the very same issue, made me so mad because it made me miss Camaro superfest this year! Believe me if you will but replacing all four oxygen sensors made my baby purr again! If you got a cheap diagnostic computer that will allow you to view live data or if a cel is on the freeze frame data and look at your fuel trims, if they are way high then them O2's is your culprit! HTH and let us know what you find out

 

Water temp sensor had the same prob after my build pulled my hair out good luck

 

Had the same problem with mine turned out to be a bad MAF sensor now my Z is running like a champ

 

Thanks for all of the tips, lots of testing is in my future.

 

Turned out to be the opti. I performed the opti test from Shoebox's site - 4th Gen LT1 F-body Tech Articles and was able to see that "B" on the ICM connector to ground was getting 0 VAC. Swapped in a new opti and it fired right up.

 

Please if you don't mind, tell us which opti you bought and from where.

I'm having issues right now with an ebay opti.

 

Sorry, just saw this. I bought a Delphi from RockAuto. Search and you should be able to get a 5% coupon code too.