99 Malibu stalling issues
#12
Senior Member
True Car Nut
both mean lean. unfortunately there are a ton of reasons to be lean. any air leak, pump shutting off vacuum leak. if you have a scanner watch the maf values. check/clean the maf.
A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor
Possible cracked vacuum or PCV line/connection
Faulty or stuck open PCV valve
Failed or faulty oxygen sensor (bank 1, sensor 1)
Sticking/plugged or failed fuel injector
Low fuel pressure (possible plugged/dirty fuel filter!)
Exhaust leak between engine and first oxygen sensor
A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor
Possible cracked vacuum or PCV line/connection
Faulty or stuck open PCV valve
Failed or faulty oxygen sensor (bank 1, sensor 1)
Sticking/plugged or failed fuel injector
Low fuel pressure (possible plugged/dirty fuel filter!)
Exhaust leak between engine and first oxygen sensor
#13
Senior Member
True Car Nut
That could also bring us back to a faulty fuel pump, which is I where I started with my first response to your thread.
#15
Senior Member
Posts like a Supercharger
Dave,
does the car also have Camshaft position sensor? if it does, have u replaced that one, or its reluctor (magnet pickup thing). I had 92 Bonneville SSEi, it would run normal, drive u to places but then once in a while would stall as well. It had a bad reluctor magnet. infact its magnet was crumpled and there was only left overs left holding on to each others, it didnt stall after i replaced that magnet, (which was a bitch to get to lol, and i end up replacing lots of other crap on way to it just for hell of it)
does the car also have Camshaft position sensor? if it does, have u replaced that one, or its reluctor (magnet pickup thing). I had 92 Bonneville SSEi, it would run normal, drive u to places but then once in a while would stall as well. It had a bad reluctor magnet. infact its magnet was crumpled and there was only left overs left holding on to each others, it didnt stall after i replaced that magnet, (which was a bitch to get to lol, and i end up replacing lots of other crap on way to it just for hell of it)
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