I have 91 gta, it has a couple things done to it. It has flowmaster exhaust, aftermarket y pipe, smog delete, 1 5/8" headers, bbk fuel regulator, Short runners, Accel base, accel cap and rotor, Taylor wires, 255 glm Holley Fuel pump made for superchargers, Vortech supercharger running 6-8 lbs., vortech boost control/ ignition, fuel pressure is set at 40 at idle and 45 at wot, Jet custom chip and new brain.

The problem I'm having is that falls on its face from 4000 rpm and up. It acts like it doesn't want to shift and something is holding it back. You can hear it in the exhaust even when you are just driving on the street at normal rpms sometimes, but it gets crapy at WOT above 4000. I just got my hands on the install instructions since I was not the one who put the supergharger on. Checked the boost box wiring and respliced it. It than ran real strong for that night, the next morning ran like crap again.

Please help, really getting angry. Really running out of ideas

 

Maybe it "knocks" and retards the timing...................

/N.

 

You sure you have a 2 bar MAP sensor? sounds like you may be maxing the MAP sensor and from my limited knowledge about boosted applications, that sounds about right at like 4000 rpm.

 

I have no idea. How would I know the difference.