Car Sputters & backfires only @ 2-3K RPM & only @ WOT ????

[superstang88]

I just started having this problem but from 2-3000 RPM at wide open throttle my car will sputter and backfire and buck like crazy but as soon as 3000 hits it takes off like a rocket? If i go at anything lower than wot through the rpm range everything is fine. I ran the codes from my comp and i get code 41 and 91 and unless i bump up my fp to around 50 w/out vacuum the code stays there, and if i put vacuum on the car it will give me the lean code no matter what. My fp drops about 5 psi if i put the throttle down with the vacuum on the regulator, is this normal, i thought the fp was supposed to stay the same no matter what the throttle position is? With no vacuum the fp stays constant and the misfiring seems a little better than with vacuum. The car has gt-40p heads, trickflow intake, 24lb injectors and a c&l 76 mass air meter. Could it possibly be a coil issue or TFI module? I already put in a new pair of plugs and it didn't help. The plugs also look good after a run. Any ideas???
Thanks,
Tyler

 

[HISSIN50]

the regulator should allow more pressure with no vac being pulled. said another way, when you go WOT, pressure should go up.

the codes you got are for the lambdas, right? just for info's sake, they could be old and bad, but their input is not used at WOT (when you have studdering).

id be lookin at the regulator (fuel in the vac line to it?) and the pump.
good luck.

 

[superstang88]

yeah, that was the code for the lambdas, i'm also getting a bad ground for fuel pump or open fuel pump, so i need to trace that down too, the misfiring is definetely less noticable as i keep adding fuel. thanks.
tyler