STS turbo tune on C5 Z06

[Rich Z]

I've got a bit of a dilemma here. I'm attaching the tune I had put in my C5Z when I had my STS turbos installed. I'm not sure this is the original one, because several months after the install, I had smaller exhaust housings put in the turbos to help them spin up quicker. At that time the car was put on the dyno again by the installer and I noticed that under boost there was quite a bit of black smoke coming out of the exhaust. I mentioned this to the installer and he didn't seem concerned about it.

I don't recall if I actually saw the car dynoed after the initial install, so I have no way of knowing if there was a second tune done after the initial install when those new housings were put on.

Well a couple of weeks ago I had some work done by another Corvette shop and just for grins we put the car on his dyno while he logged the session. He seeme quite shocked at how rich the AFR went under boost. "Off the scale" was the term he used. A later comment he made to me was that he believed it was a straight Diablo Predator tune that was on the car.

I do know that my MPG dropped about 2 mpg after the turbo install, which kind of surprised me. I know there are bigger injectors installed, but still, I didn't expect much, if any loss if the tune compensated for those larger injectors during normal cruising.

So can someone take a look at this tune and tell me what they think?

I'm not going to be pointing fingers at anyone, I just want to know what the heck is going on.

Thanks.

[5.7ute]

Your IFR table B4001 is not correct. What size injectors are you running? Is your fuel pressure manifold referenced? Any idea on what your actual fuel pressure is?

[Rich Z]

Your IFR table B4001 is not correct. What size injectors are you running?

42 lbs, I believe. Whatever comes standard with the STS kit.


Is your fuel pressure manifold referenced?

Beats the heck out of me. I'm a complete novice at this stuff.


Any idea on what your actual fuel pressure is?

The fuel pressure gauge on my pillar pod shows 60 psi. But quite honestly, when I am into boost, I have never looked at it.

I'm taking the car in to a different tuner tomorrow. Hopefully he will straighten this out for me. I'm just trying to figure out HOW it got screwed up, as the guy doing the install and the tuner are supposed to be pretty much tops in the area for this sort of thing. Any possibility that the PCM just got glitched? Been having a lot of batter/alternator problems recently and quite often had a dead battery when the car set for more than a week.

Thanks...