leebaker1973

iTrader: (1)

I have a 96 LT1 396 D1SC with 12 pounds of boost at 4700rpm. The car misfires after 4600rpm. I had Bryan from PCMforless tune the car last fall and that's when we found the problem. I didn't have a MSD box and he said it was boost blow out. I put a MSD 6al box in and it still is doing it. The plug gap is .035 and it is a new opti spark. Could it be the opti spark? Any help would be greatly appreciated. Thanks Lee

robsquikz28

iTrader: (246)

Your new opti, is it a gm opti or not?

Next would be what is your fuel pressure throughout the rpm range?

Z28Roxy

iTrader: (4)

Do your springs have enough seat pressure?

MattSapp95_T/A

iTrader: (35)

Yea Valve Spring are for sure a possibility...
Did you loctite the rotor screws in the opti?? I had a 5400+ miss and an opti with less than 150 miles on it and the rotor screws backed out...
Also do you have an in car fuel pressure gauge or on you can rig up and tape to the front windshield for a test drive??

moehorsepower

iTrader: (3)

Before spending any more money try the easiest and cheapest item first. Try closing the gap on your plugs, You are probably just blowing out the spark..

leebaker1973

iTrader: (1)

That's what I'm going to due first. Then change opti. The seat pressure is 125-130. Thanks Lee

myltwon

iTrader: (1)

what plugs are you running? what's your fuel pressure at WOT? any arching in the engine bay? read the plugs yet? what's the DCR of the motor?

ak95ta

iTrader: (3)

.035 gap? Try .025 gap. .035 is way too much for a FI engine.

leebaker1973

iTrader: (1)

That's what I'm hoping. I hope to re gap them tomorrow. Thanks Lee

bigchevyman24

iTrader: (2)

I had the same problem(on a stock motor, though). Have you checked all your plugs/wires for arcing? Try revving up the motor at night while looking on each side of your engine for arcing. I had a wire arcing, and also my coil was f'd up. New coil and wires/plugs and I'm fixed up for now. Probably gonna get an opti soon, though...lol

I_Need_Land

iTrader: (12)

may wanna see what plugs though.... i personally run a ngk "tr7", non projected tip plug. its 2+ heat ranges colder than stock iirc... i run a .028 gap also but i could probably get away with a .032 or so...

7.65" / 3.4' d1sc 355 236/246 .624/.630 blah blah blah

SCTA

I was gonna say pretty much the same. I run the TR6's at a .035 gap on mine. Never had a problem on the stock ignition setup. But your running a little more pressure than i was back then. I'd agree, check what heat range your running.

leebaker1973

iTrader: (1)

I put a set of NGK-10 and gapped them at .025. I took the car for a ride today it seems to be fixed. What plugs to you guys recommend? Thanks Lee