LT1IROC-Z

Ok, I'll give you a little back log first, I have an 87 Iroc with a pretty highly modified 94 LT1, which mods I will get to in a bit, I took my car to the track a few weeks ago and the first couple of passes car seemed to run great. As the night went on we noticed that my times were progressively getting slower but MPH was trapping high. Then the last couple passes at about 5000 RPM the car was loosing power and cutting out, so I parked the car for the night and headed home. I took it out the next couple of days to do some testing and noticed whenever the car warmed up to operating temps it would cutout again from around 4800-6000 RPM.and my wideband was sitting at about 10.5:1 when this would happen soo, I changed the opti spark, installed MSD cap and rotor, replaced spark plugs(Autolite 103's for nitrous), replaced MSD (p/n 32149) wires, replaced the MSD Blaster coil(P/N 8226), and i also swapped the ignition module from a buddies good running 94' LT1,all of this with no change,car runs great besides that, I am stumped, with all of the ignition being replaced I'm not sure which avenue to venture down now because all signs and the way the car is acting points to ignition, any advice would be extremely helpful. Heres a list of engine mods: stock TPI fuel pump, ported stock intake, ported stock MAF, LE1 heads, LT4 hot cam kit, Ford motorsports 30lb injectors, Probe forged (2256) pistons, MSD cap and rotor, MSD blaster coil (p/n 8226), MSD (p/n 32149) wires, Richmond Engineering? (lifetime warranty opti from O'reillys), Autolite 103 plugs (gapped at .040),Proffesional Products 52mm throttle body, OBX stainless 1 3/4 longtube headers, 2.5" true duals with Magnaflow x-pipe and classic chambered powerstick mufflers, CSR electric waterpump, Madtuner tune, 100 shot of nitrous (wet), etc, etc, theres a bunch more done to the car,this was just to give you an idea of whats done to the engine,if I missed anything or ya need to know more just ask, as this little hiccup is the only thing keeping me from hittin 10's this year,so please help a brotha out

LT1

iTrader: (1)

How long have you noticed this problem, has it always been like this or just recently?

Have you been able to look at the fuel pressure while it feels slower?

LT1IROC-Z

it just started doin it last time I took it to the track about 3 weeks ago,and nah, I haven't been able to watch the fuel pressure while its happening,thats my next step actually,gonna do that tomorrow..hopin its just the fuel pump..

93 LT1 Vette

Have you popped the valve covers off and inspected the valvetrain? Pushrods, rockers, springs.

banshe5

iTrader: (1)

Check the wiring going into the coil itself. We had a car that acted the same and the pink wire going into the coil had broken. I pulled out numerous harnesses in our parts bins to rob that connector but everyone was very fatigued in the same spot. GM has it so tight in the wiring harness to the coil that they all seem to have a problem. It's only this way on the dual plug coils. I hope this helps.

LT1IROC-Z

yes i have,all is good there

93 LT1 Vette

Okay a little more info. Does it pop at high RPM without using the nitrous or on nitrous passes only?