dhdenney

iTrader: (53)

I've already addressed my bad dyno pull on Thunder Racing's dyno. It breaks down above 5000 rpm really bad. Until then, it pulls well. It might be my optical or my injectors could be maxed out. I still have to look at those areas. I posted in the PCM section and I was wondering if altered VE tables could cause a massive breakdown but I was told that above 5000 rpm there is 100% MAF input. I read the little VE write up but it was late and I was kinda confused by it. I don't think a MAF could cause such behavior though. Any other possible ideas?????

94T/A

That sounds kind of like what is happening with mine. Mine pops/backfires when it gets to about 5000 rpms and I lose a ton of power...but up till that point it pulls fine.

The LT1 That Could

iTrader: (3)

sounds like optical to me

dhdenney

iTrader: (53)

Yeah injector pulsewidths are good so it's not fuel. Since I don't have the complete optispark anymore, it's either my Delteq coils or the opitcal but most have said that the optical probably isn't the culprit. My shift light will illuminate but it blinks for a few hundered rpms after it was suppose to illuminate, indicating a sporadic signal.

slow96z

iTrader: (12)

Maybe valve float? What springs are you using with that cam?

aintno6

Who is tuning the car?

Are you getting and knock retard? What is the duty cycle of the injectors above 5000 rpms?

My car pulls strong all the way to 6k on the dyno with my delteq. But if your optical sensor is sending bad signals in above 5k, it could cause missfires.

But what does your air fuel ratio look lik in your dyno pulls?

dhdenney

iTrader: (53)

Valve float? I really don't think so. I can't remember the part number on the springs but I called Crane once and they said the springs were good for .700" lift and I'm not even approaching .600". Besides I can free rev the car past 5000 but under load it breaks down there. To address aintno6, I am trying to tune the car myself. I have no input for knock retard because I unplugged the sensor. I didn't purchase an LT4 knock module and I know mine would retard with all the valvetrain mods so I said heck with it, motors didn't use to have knock sensors. I forget the math right off hand for duty cycle but my pulsewidths are no higher than 15.xx out of a possible 20 MS so they're not maxed. AFR with Thunder Racing's wideband is pretty steady in the low 13's.