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RE: Dead air flow sensor ..



At 11:28 AM -0800 11/5/99, Buchholz, Steven wrote:

>
>... clearly we're not all getting the full conversation here ... but in any
>event, one of the functions of the Motronic system is that right after the
>engine is shut off, the computer runs high current through the wire to heat
>it to 1800 degF for one second to burn off any such accumulation.

Try coating something with a little oil, then burn it off with a 
torch.  Motor oil...especially the kind that's filthy with carbon and 
other wonderful ingredients from running in the engine...doesn't just 
just "burn off" clean.  _Everything_, no matter how pure, leaves some 
sort of film or deposits, when it evaporates or burns.

The burn-off cycle on the MAF sensor doesn't really clean the wire. 
Rather, it bakes on whatever doesn't burn off; carbon and other 
wonderful things.  It does this so well that cleaning the wire 
becomes impossible. Trust me, I tried every substance in the book to 
try and clean the wire in Brandon's sensor.  I tried alcohol, 
clearvue glass cleaner(acetone and a bunch of other nasties), simple 
green, straight acetone, and finally goof-off.  Nothing came off the 
wire...the q-tips stayed completely clean.  One side of the wire 
sparkled, the other(engine side) was a dull black.  I suppose it's 
possible that the clean cycle could have failed, but that would 
probably have resulted in removable residue of oil.

The company that does repairs probably just replaces the wire, since 
it's the only component likely to go bad.  I'm guessing they 
re-calibrate the sensor using the potentiometer under the blue plug 
on the side of the control box


Brett

----
Brett Dikeman
Artel Software				617-451-9900
381 Congress Street			617-451-9916(fax)
Boston, MA 02210				http://www.borisfx.com