if i take the bypass valve off and slowley rev it up it starts to leak at like 3000 rpm, thats when its in park. i dont know if it is supposed to do this or not. There is deffinetally no boost leak in the piping we went over it more than a few times. So maybe this bypass valve is doing it. will it be bad if i just take it completley off and block the holes in the piping? thanks for all the help guys

 

Yeah don't take it off because when you do let off from a full throttle pass it will blow off the weakest spot on the tubing.. most likely the maf. What size pulley do you have? 4.0? thats recomended for 8psi.

again to the pcm.. Really needs to be tuned. You are probobly jumping into torque management really fast which will yank all the timing and fuel. you won't be able to build much boost if you are not fueling it or igniting it.

I don't know who you spoke with at procharger but I know those guys very well and I could never see them telling anyone with an odb2 vehicle it needs nothing but an FMU tune.

 

did you say a 1996? It looks newer than that. But you either have some slip or a leak somwhere. What size does it have stamped on the pulley?

 

I agree with whoever mentioned torque management. I witnessed a 7.4L chevy truck with a D-1SC on 10lbs only gain 45rwhp on the dyno. They sent the PCM off to be tuned and redynoed to the tune of 150 hp gained... It was all in the factory "tq management" pulling timing and fuel like crazy. The pcm is designed to try to save your transmission when the engine makes too much power.

 

I don't think the pcm is the problem. I ran mine with the procharger with just the FMU no other mods and gained a noticable difference and was able to get the A/F ratio to 11.4 I believe the 4.0 made 7-8 psi and 3.4 made 10 psi this is at 5500+ elevation.

 

yea its my friends tahoe not mine, and its a 4 inch pulley. Im just gonna have to tell him to get a tune and we will go from there. But ill deffinetally check out to make sure the belt isnt slipping first. WJ MARK, you ran 10psi on one of the older 5.7's? would you recomend him getting a smalley pulley before a tune, or would it be bad for it?

 

I ran into a problem with my 02 under boost the timing went south, way south. Even seen negative numbers. Kind of flying blind without logging software to see what the truck is doing. Even an areogauge would help some.
Rick

 

I had a 99 denali and put a paxton novi 2000 on it, and it did almost nothing for power. The thing would barely generate any boost...it was said to make 7-8psi, but I never saw more than 2-3psi by 3000rpm and 5psi by redline. I talked to paxton and they said that was pretty much normal, and even if I went with a different pulley setup I couldn't expect more than another psi or 2 out of it.

 

The older 5.7L (or any non LS style engine) has a much more sensitive torque management setup in the PCM. 5.3-8.1 engines respond much better to boost on the stock PCM's.