I have been fighting this LT1 surging problem for a while now. I have checked everything that I could think of. I scanned the car and watched the sensor outputs, checked for vacuum leaks, checked compression, spark plugs, wires, exhaust leaks, timing, and on and on. I replaced the o2s twice now, swapped the map, and all the other sensors are good. I finally put a wide band o2 on the car and and when the car goes into closed loop it starts to surge and the air fuel also surges from about 14.5 --> lean 17-18.

Last winter I stroked my lt1 to a 12.5:1 compression 383 with a direct port nitrous system. I am also running vp ms103 race fuel.

I have hade the computer tuned by Bryan at PCMFORLESS, and he seems to think that it is a sensor and not his tune. Does this sound like the computer to you guys? Do I need dyno time to straighten out this car and not anouther mail tune?

 

FWIW, with all the tuners I have dealt with, poor driveabilitiy is ALWAYS a sensor and NEVER their tune.