[Xzauhst]

So I just dropped in a new lt1, and it has started to hesitate and misfire a bunch. I can feel I'm loosing at least 20rwhp as the tires don't spin, and it takes forever to get to 40mph. I did plugs and wires 2k miles ago, did the maf sensor, map sensor, cleaned the ait sensor, cap and rotor, and still nothing. The o2's are reading fine as it appears with freescan. No codes have been throw, and I'm running out of ideas. The last thing I can think of is the opti. The car has 170k miles on it, and the opti is prettg much the only original part on the car. I can almost guarantee its original because everything else on the car has been original so far.

So, is it time to drop some money on an opti? I'll probably go with the one from Chandler motorsports for $175 with their lifetime warranty. I've heard mix reviews from everything but theirs was the best price and most positive feedback I've seen.

Any feedback would be greatly appreciated.

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[cocobolo95]

Have you checked fuel pressure with a gauge. 41 ps1 or more at key on prime. And same when running except pressure can be a little lower at idle because of vacuum. But 30 psi or lower is never good. Low fuel pressure can cause running problems.

Are you sure all your spark plug wires are routed to the correct spots. Also no spark leakage from wires. Check at night. Spray a little water on plug wires, just enough to dampen them, then watch for the light show.

Go to the lt1 engine section, in the sticky threads will be the diagnosing the optispark thread. Watch the video and run the tests. shbox.com also has opti testing, as well as, coil testing.

Have you checked all your engine grounds and pcm grounds for good clean, tight connections. Have you checked the opti wire harness. Quick test is to wiggle wires with engine running to see if engine behavior changes. But test wires for continuity, connectors for good tight fit, pins for burnt or bent.

If your car is an automatic, and you should always list that info, the 4l60e trans gets power from the same source as the coil and icm. So a problem with trans wiring, solenoids, or switch unit can draw down power from the ignition system. That's another reason why testing is important.