<e30 318i> re: air flow meter

[Dave Mulhouse <mulh0021@xxxxxxxxxx>]

If you are considering replacing it, take it apart first.  Many
members on the digest do not suggest that anyone should take apart an
AFM, but I disagree for the 318i cars.   The 325 uses Motronics that
requires a precisely calibrated afm, but I believe that this is not the
case with the 84-85 318i that uses L-jetronic.  (If I am wrong someone
please correct me)  To take it apart you will need to pry apart the
black cover on top of it.  You should remove it from the car before
doing this.  The first test on the AFM can be performed without taking
it apart.  Once it it out of the car, see if the air flap inside it
moves without any restriction.  Take a pencil and push it through its
range of travel.  If the flap rubs or binds against the housing, it
needs to be replaced.  The second test is to check the resistance tract
inside the afm.  If you see chips missing from the resistance tract, it
is bad but sometimes repairable.   Barry Burr can give you detailed
instructions on this, but basically it involves bending the wiper arm so
it doesn't contact any of the missing "chips" from the resistance tract.
The second test can also be performed with a volt-ohm meter.  You can
either check the resistance on the afm while you push the air flap back
and forth, or you can supply a test voltage to the unit, and measure the
voltage drop across the wiper arm and the resistance tract.  The latter
will give better results.  When you do either of the test you are
looking for voltages or resistances that drop out while you move the air
flap.  If you need pin-outs from the AFM let me know and I can look them
up. 


>I believe i need a new Air Flow Meter, but my mechanic says it maybe
>something else.  He hooked the comp up and it showed that nothing was
>happening in the Meter housing, so in turn, the car barly runs.  Is he
>right?, or is something causing it not to work?  A new one is $250+ so >i
>want to make sure i'm getting the right part!

>I would appreciate it if you replied to me directly
>Jake@domain.elided

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