Mass Air Flow (Maf) Sensor. Replacing - BMW 5251 Service Manual

Fuel Injection
I
4
Release spring clips (arrows) from fuel injectors and pull in-
jector electrical loom straight up to remove.
4
Check that ECM signal is present at injector connectors.
-
Connect digital voltmeter to fuel injector harness plug.
Operate starter and check for voltage pulse.
* Repeat for each injector.
-
Remove fuel injectors by removing retaining clips
-
Installation is reverse of removal:
Fit new O-rings when installing injectors. For ease of instal-
lation, lightly lubricate all fuel system O-rings with assem-
bly lubricant.
Check that injector electrical connections are correctly fit-
ted and that injectors are fully seated prior to installing iuel
rail mounting bolts.
Mass air flow sensor (MAF), replacing
The MAF sensor is provided with operating power from the
ECM relay. Based on calculated intake air mass, the MAF
generates avarying voltage (approx. 0.5
-
4.5 vdc) as an input
signal to the ECM.
4
Remove MAF sensor:
Remove upper air filter housing locking clips.
Unscrew and remove MAF sensor harness (A).
Disconnect intake air temperature sensor harness (B).
Loosen hose clamp
(C).
Remove upper filter housing with sensor.
-
Installation is reverse of removal