MAF (Mass Air Flow) Sensor testing?

[rocksteadyX5]

Is there a definitive way to test the MAF sensor to determine if its going/bad?

Problem (2002 3.0i): CEL is on and it failed emission testing. In the pass months I changed the Pre-O2 sensor, replaced the crack intake eblow, Replace the DISA valve (It was about to break off), Changed the Spark plugs and coils. Still I can't get the CEL to clear. The only thing that has not been changed is the MAF.

I scan for codes and see misfire in 1 & 2 and code for Pre-o2 sensor.

I plan to switch around the plug on 1 & 3 to see if it follows. Wanted to test the MAF before changing it.

Any thoughts or idea would be great.

Thanks

[Bimmer Tool Rental]

I have never had any definitive luck testing a MAF. It seems to be in one of 3 stages. It works, it is degrading performance, it is hard failed and the car is having serious issues. I have good and bad luck cleaning before.I have had a MAF or 2 fail on me after cleaning. Unplugging the MAF isnt a great way to test always. Find someone with a good MAF in your area and meet up.

To definitively rule out bigger issues.

Move coil and plug together from 1 cyl to a good cyl. If it still exists, move the injector too. This will tell you if it is one of the main components. Work back wards to tell what component is causing the failure. Good time to do a compression check as it gives you a baseline to work from.

Best of luck!
Kaine

[civdiv99]

Monitor pin 5 of he MAF with a meter. You will NOT be able to make a qualitative determination by revving it in the driveway, but - nevertheless pin 5 voltage out will vary with, and increase under, load. When mine failed, that pin was static, indicating a hard failure. (supported by diag code). If it's functional but flakey, your system will set a plausibility fault - basically says what it sees from the MAF is not plausible with other data. When this occurs, it will throw a MAF code, and revert to static table in memory (limp home it used to be called). If you unplug the MAF, therefore, the car will still run (perhaps a bit flakey), but you will add a MAF failure specific code to your list.

Any number of OBDII scanners let you monitor the MAF signal and the interpreted load and interpreted air mass flow in real time, which is pretty handy when analyzing stuff, but at some point you'll need to spring fer the toolage, or get access to some diag goodies in some fashion to work through this.

I realize this doesn't bring you closer, but perhaps it addresses your "MAF test" question.

Good luck with your testing.

[rocksteadyX5]

Thanks for the feedback. I took the easy route - swap my MAF with a known good one and same issue. The only thing I could think of that is a known issue was the CCV/oil perpetrator. Took it to a local indy shop to do the smoke test and BINGO - puff puff the magic dragon. So I am waiting for my CCV parts to show up and reviewing the different DIY floating around -looks like its going to be a PITA.
Going to sell her when all is done - wanted to make sure she is at least in decent shape. Play it forward and all that!!!

spotted my new lady all dressed in red 4.4i.....so need to get this knocked out soon.