Ru2slo_99

I have a 1994 Z28. I have had opti problems before and this is different. My car runs fine when it is cold, but once it warms up it misses bad. I thought it might be plugs and wires and replaced them with no positive results. I changed the coil and ICM. I heard that sometimes when the ICM heats up the car will miss. This did nothing. Freescan shows no codes, its running lean, 12 volts, and everything else looks normal I think. I thought maybe the fuel pump was not supplying enough fuel. I drove around all of today with a fuel pressure gauge. The pressure was around 32 at idle and 43 at WOT. I thought unplugging the MAF would make the computer stay in open loop mode incase the O2 sensors were screwed up. But it still misses bad once it warms up. I NEED HELP!

Any ideas?

andysc

iTrader: (6)

Fuel pressure at idle should be 40 and 45 at WOT I believe, so you either have a restriction, clogged fuel filter, or bad pump.

hth

andy schuck

86formula

iTrader: (3)

i had that problem and it was my O2s when was the last time they were changed?

Smoke Em

^^ check o2s

Ru2slo_99

I will change the fuel filter this weekend.

I changed the O2 sensors a little over a year ago because of a failure. If the filter does not do anything, I will try new O2s.

I set the FPR at 42psi so the WOT pressure is what it was. If it was a fuel problem why would it run fine before it warmed up?

Smoke Em

when you floor it does it hesitate bad and skip, and barely move like it should?

Ru2slo_99

Yes! It snaps and snarls and pops at any throttle position. Anywhere from cruising to WOT.

rat93

iTrader: (2)

o2s, they dont do anything on cold start

pillarpod

vacuum problem?

Ru2slo_99

I have sprayed WD-40 all over the engine while it was running with no stumbles. How do I find a vacuum leak?