1998 Chevy Malibu Runs Rich

ROVERTECHGOLD

MEMBER
1998 CHEVROLET MALIBU
6 CYL
FWD
AUTOMATIC
138,000 MILES

I am currently trying to diag a rough idle, lack of acceleration. No faults present. Checked live data, the MAF is reading.50 lb/m, MAP 11 to 9 "hg, LTFT -9%, short term is switching good, the primary O2 is switching, and the secondary is about.750, the ignition advance is 17 to 19 degrees. Removed the EGR and verified that it is not stuck, has clean air filter, removed and checked the plugs. Fuel pressure KOEO is 45 psi, 36psi at idle and jumps to 45 when the vacuum hose is pulled from the regulator. There is no fuel present in the regulator. The pcv is not stuck. The intake gaskets are leaking coolant. I am not familiar with GM and have hit a wall. Any help would be welcomed.

2 Replies

RHALL77

MECHANIC
3,361 POSTS

Check your fuel filter and cat converter. These are common for lack of power. This sounds gross but try to blower through the filter and see if it is possible. How do the plug wires look?

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Wednesday, March 18th, 2009 AT 2:33 PM

DON OLIVER

MEMBER
101 POSTS

Fuel pressure should be 41 to 47 at idle. Have you removed the o2 in front of the cat to check for excess back pressure? It'll be noisy but if it runs ok then, the exhaust has too much back pressure. When you disconnect the regulator, it should give max fuel pressure. Even then, it seems low. Good luck