Mechanics

PONTIAC BONNEVILLE SENSOR PROBLEM

2001 Pontiac Bonneville • 150,000 miles

The car stalls when first started, if I feather the gas it will stay running, after 5 minutes or so it will then run fine, and start fine until the next "cold" start. Interestingly enough this only started to happen after a routine maintenance (oil & filter, and fuel filter change) It does show an SES light (lean code) as if it were a bad O2 sensor, but I believe this is a symptom rather than cause. I was leaning toward a fuel pump but it doesn't make sense that it runs fine after 5 minutes of "stumbling"?
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HenryJ
January 3, 2013.




What is the code number as it may be a vacuum leak causing this.

Idle control motor may be mal functioning as well

Roy

I do not remember the code # but is was "Lean Bank 1" I believe as the description

Tiny
HenryJ
Jan 3, 2013.
Is the light back on?

Roy
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No it's currently off. I disconnected the MAF to see if that would get it back to stored factory codes, but it ran the same.

Tiny
HenryJ
Jan 3, 2013.
Doing that does nothing but create issues. Never dis connect a sensor while running

Roy

Cleared all codes this weekend, just to be sure nothing was caused by the unplugged MAF. Removed the IAC and cleaned it and the TB passages, cleaned the MAF, changed air filter, and coolant temperature sender. Tested fuel pressure, 48 psi running, 52 psi regulator vacuum un plugged. Checked the resistance of the air charge sensor seems good 2.6 K-ohm.
Same problem, when first started "cold" runs fine @ high idle for 1 minute, then idle drops to the point of stalling, if I keep it running by feathering the throttle it clears up in 3 minutes and runs fine, until next cold start. No SES light set.

Tiny
HenryJ
Jan 7, 2013.

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