I ordered a Wait4me tune on my 1997 chevy 5.7 ECSB Z71 with 3.42s, intake, high flow cats, true dual exhaust, and free mods. The truck does pull alot harder (feels like there was room for more tuning but its a W4M not one of the "high end" tunes) but when it gets close to 5K RPMs it feels like it falls off almost. So far i have been told to check the fuel filter, drive shaft balance, u joints (which i know are going bad), differential fluid (not likely), or possible A/F ratio, which i have no means of seeing. My question to yall is has anyone ever experienced this problem? Or heard of this problem? Whats yalls intput?

Barrett

 

Did it fall off around 5k rpms before the tune??? My experience is that the 5.7 vortec usually quits breathing well around 5k rpm, which would explain the fall off.

 

well so far thats the best answer i have heard and i think you for that. It will shift just before 5K and it doesnt fall on its face, but it does pull a little less. Could i put an intake manifold spacer on it to slove the problem? Or is a new intake manifold in order? I hope not bc that wont happen. Ill send the tune back before i buy a new manifold, at least right now.

barrett

 

throttle body spacer?? not worth much more than a paper weight IMO.. If your wanting to spin it up past 5k youll be looking at a larger cam, maybe some head work<valvetrain upgrades deff>, and yes a marine intake would help the situation. If your on a budget I'd keep the tune and drive it like ya stole it while enjoying your bottom end power and leave the 5k + to the GEN III guys.

 

No i wasnt taking about a throttle body spacer, i was refering to an intake manifold spacer. I read a thread on Fullsizechevy that talked about one about a few months ago. I know nothing about them; just threw it out there. I am aware that the TBS will do nothing for my truck. Im also not trying to build a 5000 plus RPM engine, i am just trying to figure out what the strange noise/feel is, and what is causing it. I do have the stock intake manifold, throttle body, etc. with an aftermarket intake so what do yall think the best shift point would be? Probably a little below 5K correct?

Barrett

 

How does it act compared to before the tune? Obviously you said it pulls harder, but how did it act in the area you are having the problems in now? If it was fine before, then I would call him and tell him what it is doing, and he may just need to adjust something. Or it might just be that the truck is making more power now, but the intake/cam might be the limiting factor, and you just notice it more.

 

Im pretty confident that my intake manifold, cam, heads, etc are just slightly limitimg now bc of the new tune. I can now feel the need for better, higher flowing engine internals. Maybe more work is in order??? What would be the power increase from my setup now in the sig to the same with intake manifold, mild cam, and some higher flow heads? (not sure which ones, not knowledgeable in that area)

 

I don't know about power increases or anything, nor do I know what to recommend. I don't have much experience with those motors, except in extremely stock form...

 

You can't get more than 5k out of stock heads. The stock valvesprings are so light you can actually open them with your bare hands on Vortec heads. If you want more than 5k you have to upgrade the valvetrain.
Also, stock cam is a torque cam. Torque peak on an L31 is at 2800RPM. The stock intake manifold will support 5500, not WELL, but it will support it. The stock PCM supports up to 5800 maximum RPM.

 

thanks for the info james. Whats the best in the tahoe?