I have recently moved to SD on my 94Z and don't think I will look back. I've read all the pros and cons but I will tell you if you have an OBD1 pcm, 58mm TB, and 42lb injectors it virtually eliminates the lean tip-in/pop you get running a MAF. I have my VE pretty much dialed in using the NB O2. I have set the 400,800, and 1200 %TPS WOT to 0 to run OL idle. Right now at 900RPM idle my IAC count is about 30-36, ~60 MAP and ~25 deg timing. The 100RPM/60MAP VE is 52% and 800RPM/60MAP VE is 49%.. can anyone compare this to their SD tune to see if I'm close? It still smells a little rich but I'm not sure I can tell the difference from rich or unburnt fuel from cam overlap. Next on my list is to hook up my wideband and get part throttle and WOT dialed in perfectly.

 

This is encouraging. I have a customer that's having a bunch of surging problems with their supercharged C5 and we were going to explore doing an SD tune for it.

 

from what I've read there is a problem using a 2 or 3-bar map in that on key-on the pcm does a calibration for atmospheric and expects 5v from a 1-bar map, this would not be the case with a 2 or 3

 

Yeah, this setup (A&A Corvettes Supercharger kit) uses the stock 1bar MAP. It knows how to add fuel by using a "boosta pump". It basically overdrives the fuel pump voltage when the manifold pressure references boost. Not very scientific but gets the job done.

The problem we're having is at cruise throttle position (around 10%), between 1000 and 2000 RPM, the thing surges really bad. We suspect turbulent air across the MAF is tweaking the PCM out.

 

sure its not something to do with the bypass valve?

 

Man, your still having the problem with that vette? I posted when you first posted about that vette last month but never saw if you had results. Where is the MAF in relation to the BPV itself? Do you have a pic of it? Where the MAF is in relation to the BPV that is.

Ken R.

 

where is the maf located, i have seen gm maf sensors do strange things when they are on the intake/boost side, i have had better results running the maf on the air inlet side of the supercharger(this way the airflow is the same as stock, not forcing air through it)

 

Still working on it. Part of the deal is that its an automatic car, and automatics upshift quickly and tend to lug the engine. We got rid of most of the symptom by delaying TCC lockup above the surge RPM zone, but it's still slightly noticible.

The MAF is on the boost side, in the stock location. The BPV seems to be working OK because there isn't a bunch of fluctuation in the intake pressure.

 

is the BPV before or after the MAF?

 

Before the MAF (the MAF is basically in the stock location on this setup).

I spent more time on it yesterday, the LTFTs were a little lean so I brought those back to the slightly rich side, it seemed to help, but the ultimate test is with the customer. ;-)

 

This is resolved. I wrote up my findings in the original thread: http://web.camaross.com/forums/showthread.php?t=504448

Thanks for all your help