Please help solve a Missing Problem

Reply Subscribe

Thread Tools

Search this Thread

Dec 3, 2009 | 09:03 PM

Ru2slo_99

Thread Starter

On The Tree

Joined: Sep 2003

Posts: 177

Likes: 0

From: Vicksburg, MS

Please help solve a Missing Problem

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?

Dec 3, 2009 | 09:38 PM

andysc

On The Tree

iTrader: (6)

Joined: Jan 2009

Posts: 152

Likes: 0

From: Newport NC

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

Dec 3, 2009 | 09:54 PM

86formula

11 Second Club

iTrader: (3)

Joined: Oct 2006

Posts: 879

Likes: 0

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

Dec 3, 2009 | 10:05 PM

Smoke Em

TECH Enthusiast

Joined: Mar 2009

Posts: 722

Likes: 0

From: RI

^^ check o2s

Dec 3, 2009 | 10:26 PM

Ru2slo_99

Thread Starter

On The Tree

Joined: Sep 2003

Posts: 177

Likes: 0

From: Vicksburg, MS

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?