I just finished a rebuild on my 94 Z28 and I am having idle issues.

I built it up a 350 c.i. with a LT4 intake and heads, manly valves, CC 306 for a cam, stronger springs, KB hyper... pistons with a compression ratio around 11:1. 95 opti upgrade, Hooker LT's, no cats, SLP loudmouth the rest of the way, tuning through PCMSFORLESS and stock throttlebody and injectors for now.

the problem I am having is in closed loop (after it warms up) it doesn't idle good at all and dies. I have head my fuel pressure set between 39 psi and 50 psi with no difference. I have ohm'd out my IAC and both coils checked good (around 65 ohms). I have checked the TPS and the computer is suppling 5.01 volts to the TPS and I am reading 0.71 closed and 4.67 open through the TPS. So I know those two things are good.

The only things I haven't done yet are

1. adjust the throttle stop screw to see if that tells me if I need to drill out the IAC passage.

2. I heard that ported MAF ends can give you idle problems, so I'll try puting the stock ones back on. I have the Thunderracing polished MAF ends on it now.

3. I have an Aeromotive adjustable FPR on and I heard that they are garbage, so I might try puting the stock FPR back on.

I don't have the capabilities of datamaster yet so I don't have any logs or anything to give you and my car won't let me check for any codes via the jumper wire method so that too is out for now.

I know I could use larger injectors and possibly a new granitelly MAF and larger TB but funds are alittle low right now.

Any Ideas on what might fix this? It's so fustrating to do all that work and not be able to drive it.

Any help would be greatly appreciated!!

John

 

TTT

 

I bet it could be your MAF or the IAC. Either one will give you trouble at idle. The best way to troubleshoot these cars is with the right software, but you know that already. Small injectors won't give you trouble at idle, though, so I's look into air/fuel management systems. Good luck.