re: E30 Intermittent engine cutout

[jkerouac@xxxxxxxxxxxxx]

re: E30 Intermittent engine cutout

     The description sounds typical of an Air Flow Meter problem.
There is a carbon band that the copper pointer tip slides across.
Effectively this is a potentiometer.  Over time, the carbon wears
through.  Also the tension on the pointer arm gets weaker.  Then the
pointer give infinite resistance where the carbon wore thin, so the ECU
gets faked out into responding as if there is no air going through the
AFM.

     One way to test if this is the problem is to remove the plastic
cap.
Look for buildup of carbon dust on the band.  There may be one stretch
of a few mm or more where the buildup is heavy.  Possibly there will be
a visible thin spot or worse.
     If you can catch the engine when the cutout is happening, try
pressing lightly on the pointer tip at the point against the band.  If
the engine comes back to life, this is definitely the problem.
     I would guess most likely the cutouts first happened at partial
cold engine conditions, such as when the engine was hot, parked for a
bit, then restarted.

     This applies to any "trap door" style AFM.
Two cures:
Replace the AFM at ab$urd expen$e,

Open the plastic cover on the AFM.
  _Gently, with curved tip needle nose pliers, bend the arm upward.
  Then bend the two arms of the pointer. downward.  This results in
increased tension on the arm.  Now bend back up slightly the pointer tip
where the contact slug of copper is.

  This will accomplish:
     Restored tension to the pointer arm,  and
     the pickup point will now be slightly inward or outward of the
original arc on the carbon band that it used to swivel on.  Since that
is a fresh area that will not have been contacted before, its like
having a fresh carbon band in your AFM.

Good Luck.
'jk

------------------------------