When I unplug my MAF....

[rob350]

My car dies. When I go to restart it, it runs for a second, then dies. When I plug my maf back in and it runs. Is this normal? i always thought the car ran with the maf unplugged.

Rob

 

[Boy Buick85]

No you definitly want to leave it plugged
in.Thats how the ECM interprets whats going on with the air flow

 

[Daniel Jost]

Well i guess you are working on your trouble shooting skills . Well we found out the MAF is working good!

,Dan

 

[Boy Buick85]

LOL sorry i must have misunderstood the question Glad u fixed it though

 

[Hotair85]

The reason it won't run is the fact that the ECM doesn't have a preprogrammed algorithm in it to take into account incoming air when the MAF is disconnected. A speed density system (one that doesn't use a MAF) will use an algorithm that is preprogrammed into the PROM chip to figure out how much air is entering the engine via the MAP sensor and crank/cam sense. It also corrects for engine operating temperature differences.

Most OBD-II GM cars with a MAF system have a sort of speed density backup algorithm. If your MAF goes on the fritz the car goes into a "limp-home" mode that triggers the MIL and uses a backup algorithm preprogrammed into the PCM to get you home. It'll run, and you probably won't notice anything out of the ordinary (except maybe at the gas pump), but it won't run optimally. That's the over-simplified version of why your car won't run when you unplug the MAF sensor.

HTH