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sprinkles08, ASE Certified Technician
Category: BMW
Satisfied Customers: 23127
Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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I have an 07 mini r56 with an 2b5c mass air plausibility

Customer Question

I have an 07 mini r56 with an 2b5c mass air plausibility code
I smoke tested the intake found no leaks
The customer complains of rough idle and it has had 5 mass airflow meters replaced each purchased from mini
At a stand still since shopkey data on this is limited
Submitted: 1 year ago.
Category: BMW
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

This is a performance type code that sets when the mass airflow signal isn't valid for operating conditions. This sets when there isn't enough airflow seen. Possible causes are the sensor, it's wiring, or a leak allowing air into the engine that isn't being measured.

If the sensor has been replaced with a factory part five times then there is little question that you can rule it out.

Has the sensor wiring been tested?

Will the engine run if cardboard is introduced over the throttle body?

Customer: replied 1 year ago.
Wiring has been tested
Had 12v
Dme ground
The 5v reference was there
Did not try cardboard to the intake but intake system was smoke tested with no leaks
Expert:  sprinkles08 replied 1 year ago.

There isn't a way to seal an intake to properly pressurize it with smoke because some intake valves are always open, so I don't put much faith in 3 PSI of smoke to find a vacuum leak. Try the cardboard and see if it will die or continue to run.

Customer: replied 1 year ago.
It died after cardboard was introduced
Expert:  sprinkles08 replied 1 year ago.

What is the MAF grams per second with the key on engine off and with the engine idling when the code is active?

Customer: replied 1 year ago.
2.40 koeo
10.4 koer but jumps around
Expert:  sprinkles08 replied 1 year ago.

If it's showing airflow without the engine running then you have a wiring or sensor issue, it should be zero without air moving across the sensor.

Customer: replied 1 year ago.
you are right but
I have
Dme ground
5v reference and have voltage return
Sensor is new purchased from mini
Expert:  sprinkles08 replied 1 year ago.

Something has been lost in testing, the sensor is bad or the failure is internal in the ECM (unlikely). Either the sensor is inaccurate, there is a wiring issue altering it's signal, or the ECM is interpreting the signal voltage incorrectly.

Customer: replied 1 year ago.
I'll do some more checking and get back to u
Expert:  sprinkles08 replied 1 year ago.