Checking MAF with OBD
10-11-2011, 02:42 PM
#1
Racer
Thread Starter
Checking MAF with OBD
Hi all,
I'm trying to check if my MAF works correctly with OBD2 live data logging but I have no clue about 'normal' MAF airflow values. So far I 've only done data logging with engine idling (warm engine):
Long-term fuel trim Bank1 +0.7812%
Long-term fuel trim Bank2 -1.5624%
MAF Airflow 6g/s (=21kg/h = 46lbs/h)
O2 sensors 1-4 all normal
Fuel trims look okay so I guess nothing can't be too wrong, but does anyone have reliable reference values for OBD2 MAF airflow? What kind of values should be I looking at idle and under load (full throttle? what gear?)
I'm trying to check if my MAF works correctly with OBD2 live data logging but I have no clue about 'normal' MAF airflow values. So far I 've only done data logging with engine idling (warm engine):
Long-term fuel trim Bank1 +0.7812%
Long-term fuel trim Bank2 -1.5624%
MAF Airflow 6g/s (=21kg/h = 46lbs/h)
O2 sensors 1-4 all normal
Fuel trims look okay so I guess nothing can't be too wrong, but does anyone have reliable reference values for OBD2 MAF airflow? What kind of values should be I looking at idle and under load (full throttle? what gear?)
10-16-2011, 04:23 PM
#2
Racer
Thread Starter
Went driving and logging some more, 4th gear at WOT 5600 rpm I got 213g/s (= 766kg/h) MAF Airflow.
MAF idle and load values are vaguely similar to stuff I've measured from my BMW's so I guess that's what I'll have to settle to. It's kind of frustrating that there's this really neat diagnostics capability in the car, but there's no public reference data in WSM or interweb to interpret it
.
MAF idle and load values are vaguely similar to stuff I've measured from my BMW's so I guess that's what I'll have to settle to. It's kind of frustrating that there's this really neat diagnostics capability in the car, but there's no public reference data in WSM or interweb to interpret it
.
10-22-2011, 04:10 PM
#3
Racer
Thread Starter
Continuing this lonely monologue. I found an old post by Bill about WSM OBDII supplemental pages.
On the FactoryDetailedEngSpec.pdf attachment's last page some airflow references values are given. Unfortunately no load values are given and the below range is a bit vague:
Air mass no load idle: 15-27 kg/h
Air mass no load 2500rpm: 34-64 kg/h
Still better than nothing. So, if you suspect that your MAF might be going bad, you can check whether your idle airflow measurement is still within factory specified range by a simple measurement with a OBD2 scanner.
On the FactoryDetailedEngSpec.pdf attachment's last page some airflow references values are given. Unfortunately no load values are given and the below range is a bit vague:
Air mass no load idle: 15-27 kg/h
Air mass no load 2500rpm: 34-64 kg/h
Still better than nothing. So, if you suspect that your MAF might be going bad, you can check whether your idle airflow measurement is still within factory specified range by a simple measurement with a OBD2 scanner.
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