noahz28

I have never posted anything on this forum before but have been a member for a few years, I look at it a lot when i am trying to answer a question i dont have an answer for. I have recently donw some work to my 95 z. Lt1 of course with 6-speed. I replaced cam, Machined the heads, also replaced the optispark in addition to new wires and pluggs. Also purchased the 300+ accel ignition system.
The problem i am having is the car falls on its face at 4500 rpm, with or with out the accel system. When hooked up to a scan tool the computer will either not run a code or if it does it will show something different every time. vacuum is good. and i dont know what is going on HELP

shoebox

Have you checked your fuel pressure with a gauge?

noahz28

Actually no, Mainly because of the codes that the computer is pulling up. Although i had thought of that and that was going to be my next step anyways, change filter and check pump. But would the computer be throwing codes about eletrical and mass air if the fuel psi was low???

shoebox

Your original post was pretty vague about what the computer was doing, so there was not much to analyze (no mention of MAF). If you leave out details, all people can do is make wild guesses. You have to start ruling things out and fuel pressure is one of the things.

noahz28

ya it was kinda vague. Well i put on a fuel filter and still seems to be having hesitation. I check the EGR valve and it isnt stuck open. The other funny thing about it is that it only does it when it is under a load, sitting in idle i can tach it to 6k no problem and no hesitation but once i take off down the road it has a hesitation off the start and then at about 4500 it falls on its face but it is real inconsistant. sometimes it will be ok. could the throttle position sensor or o2 sensors be screwed and not have the computer know it? and what happens when a knock sensor goes bad, i wondered if maybe the cam is causeing a problem computer or sensor wise???

noahz28

oh fuel pressure is good too. forgot to add that

TobyZ28

I had a similar problem at WOT and high rpm. Engine felt like crap once it hit a certain point. Replaced the fuel pump and it fixed it no prob.

noahz28

was the fuel ps1 good before u replaced it? or did it show that is was bad?

RMC

Yeah we need info on your combo.

Do you have bigger injectors?

When you say machined the heads did you have them ported?
If so mild port, full port and polish, bigger valves?

Basically, I'm curious if you still have stock injectors but put heads/cam on it. If so you may be starving that engine of fuel.

But I have no idea without more info on the setup.