tjmxer

I receintly purchased a 94 Z/28 and the previous owner spent alot of money on it. It has a fresh Eagle 383 rotating assembly, Comp cam(.495/.503, 218/224duration@.050), 30lb accel injectors, BBK 52mm throttle body, MSD ignition, LT4 knock module, BBk headers, Y-pipe, Borla Exhaust, Zoom kevlar clutch, Moroso intake. Its a 6 spd with a stock rear. The car runs really good until you give it full throttle. It surges or hesitates, only when its wide open and under a load. If you let off the throttle slightly, it goes away. I've looked around on this site before, and it seems like the car is pulling timing. I installed a LT1 knock sensor thinking that was it. It helped a little but its still doing it. The pcm was sent out to PCMforless.com for a reprogram by the previous owner. Do i need to take it somewhere that has a chassis dyno and can reprogram the pcm on the spot? I believe the car still has the stock fuel pump, also. Could this be it, not enough fuel? I hope someone can help me out.

Guest47904

Look at the signal from the TPS while moving it slowly and see if it has a dead spot when the throttle is near the position you speak of.

tjmxer

How do I do that? Do I need a special tool?

Injuneer

Have you scanned it for codes? Have you checked the fuel pressure? Have you tried cleaning the MAF sensor? Have you checked the inlet air elbow for tears, or the bottom being folded under at the bottom of the throttle body?

tjmxer

Yes, no codes. No, what should the pressure be? At wot? How do I clean the MAS? It had the screen in it when I got it and I removed it. It runs the same either way. Yes i did. The only thing is the previous owner put a hole in it for the distributor vent and it doesnt look like he sealed it at all. Could that be enough to cause the problem?

Injuneer

Fuel pressure should be at least 40psi at WOT/max RPM/max load.

Go to your local auto parts store and buy a can of MAF sensor cleaner.

Put the screen back in.

Plug the hole in the inlet elbow. Its letting hot, dirty, unfiltered air into the engine, and that air is bypassing the MAF sensor. Probably not enough to cause a problem of the magnitude you are having, but common sense should tell you that you don't want hot, dirty, unmeasured air going into the engine.

You interchanged the words "knock sensor" and "knock module" in your first post. Was that intentional?

mrmint69

Unless you have a fuel pressure gauge already go buy one with a hose long enough to run it from the schrader valve to the windshield area. This way you can place it under the wiper and go for a drive and monitor it while you drive.