I went to go start my car today and the ses light and code 48 came up on the scanmaster. I could hear the fan kick on right as i started. The car has not been running right for the few weeks. Stumbling, backing firing and bad idle.

Are these signs of a bad maf? Is there anyway to check it out to see if it bad? Or trouble shoot it?

Thanks

 

Unplug the connector to the MAF and see if it runs better. The PCM will allow the engine to run in speed density mode.

 

If it runs better replace the maf? I found a new maf local just wanted to order it before they close today.

 

Removing the MAF in your case will do nothing. Because of the DTC set, you're already in speed density mode.

Anytime you have a sensor problem, the FIRST thing you do is check for voltage and ground at the sensor if it's the type that has it. So, check from the pink to the black wire for 12 volts. Then you check the yellow wire for continuity from the MAF to the PCM on the black connector 3rd pin from the end.

The next thing you can do to test the performance of the MAF is check its response. Since the common person doesn't have the ability to view the response of the MAF with a scanner that can read all of its frequencies, a volt meter that can read Frequency is the next best thing.

You want to check the response of the MAF signal on the yellow wire with the engine running with the meter in Hz. Read from the yellow wire to ground when you momentarily SNAP the throttle. The reading should be over 7KHz. If it's not, try cleaning it. If it still is low, then replace it. But don't go replacing it until you check for supply voltage and ground and integrity of the signal wire.

One last thing, we know you have OBDI but it would be nice to know the year of the vehicle.