Check/clean those MAF sensors - esp. if you have fuel mix problems

Joel Lenorovitz jlenorovitz at
Mon May 6 18:31:06 EDT 2002

Well after months and months of diagnosing, searching, guessing, swapping, testing,
cursing, and frustration, I FINALLY found the solution to my fuel mix woes.  Turns
out that it was not the O2 sensors, or a vacuum leak, or the EGR system, or the ECU,
but rather

a dirty MAF sensor element

This was incredibly hard to diagnose properly (even w/help from the dealer and an
independet shop) because the sensor was not dead and the output was not so far out
of whack that it seemed erroneous.  But after all the dismantling, cleaning, and
replacing parts of the items mentioned above to no avail, I fortuitously stumbled
upon this link and it changed my life: (scroll down to MAF section)

It was the high NOx levels found when my car failed emissions that put the last
piece in the puzzle.  I knew for sure that when my car actually ran better with the
MAF *DISCONNECTED* that we had our man (I guess fuel mix must also be adjusted via
the throttle position sensor).  Though only a barely visible film of dirt was
present on the sensor, cleaning it off with some carb cleaner and a soft toothbrush
made a world of difference.  I used to get frequent check engine lights, lean fuel
mix codes, overall degraded power with regular "limp home mode" activations (i.e.,
ECU kicks in to full-rich mode out of confusion?), and, high NOx.  Now she's running
like a top and has more power than ever before.  The MAF sensor is the easiest thing
you can get to on the 12v-V6 (though you do have to pick up a security torx bit), so
have a look at yours if you have 15 minutes and clean it up if it needs it.


P.S. - I have a feeling that using a K&N filter may have contributed to the dirtying
of this sensor.  They do flow more air, but more air (through the same size filter)
= more dirt, most likely.  I've switched back to the OEM paper element for now so
we'll see how that affects things.

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