Shutting off at idle, bad Mass Airflow sensor
 

Hello. My 2001 SS Monte is cutting off at idle at stop lights and such and idling rough. The fuel mileage has dropped dramaticly. I took the Monte to a respected garage and their scan showed a bad Mass Airflow Sensor. They replaced it and the problem still exist. The mechanic apologized and said he did not know what else to do to fix it. He did not charge me. He did say I could unplug it and drive, I did and the car appears to run fine but the fuel mileage is in the high teens so I know it needs fixing. Have any of you had a new sensor be bad? What else could be the problem? Any ideas will be appreciated!

Thanks!

Did he use an AC Delco MAF or another brand? The reason I ask, it has been seen that sometimes non-AC Delco MAFs are not as good. That *might* be part of the issue. And this may also be some silly questions:
- Any codes stored in the PCM?
- Check the wiring for the MAF to ensure it is not having issues?

I'm not sure about the brand he tried. I will purchase an ACDelco one and try it myself. He didn't mention any PCM codes. I will check the wiring to be sure it's good, but I'm thinking it must be okay since when I unplug the mass air flow sensor the idle levels out and runs good, just extremely inefficient.
I normally work on my own stuff but have been out of town some, and the shop I took it to is generally pretty good for general stuff. I think I'm going to go ahead and purchase my own scanner. I have a 2007 Silverado and my girlfriend has a 2012 Subaru Forester, so it will be handy to have one with the older vehicles. Do you have one that you would recommend? One that would also read PCM codes.

Just because it runs better after unplugging the MAF, doesnt mean its the maf. It most likely is and I 2nd the AC Delco replacement but ive had an IAC problem that would go away after unplugging the MAF. Ive found that blasting the MAF element with electronics cleaner can give it a little more life also.

I use the Torque pro app and a bluetooth dongle. Does live data and codes.

Good information. What is the IAC, idle air control? And what is the problem you speak of?

I know its beating a dead horse, but Ive also personally seen dead out of the box aftermarket MAFs on this platform.

Thanks, I am going to pick up a A/C Delco and put it in this weekend. Even if thats not the final issue it's 21 years old...

Yea thats it, and it was just stuck. Electronics cleaner unstuck it.

Cool. As soon as the sleet n snow is over I'm going to pull it into the shop and check it. I can't quite close the shop doors right now because of some things that can't go outside:cool: and the snow and sleet here is litterally sideways right now.