re: failed emissions

["Todd Kenyon" <todd.kenyon@xxxxxxxxxx>]

You can lower the CO by opening the AFM bypass screw (loosening it). It
is under a small plastic plug (yellow or blue) on the AFM - you may need
to screw a screw part way into this plug and yank on it pliers to get it
out. It's supposed to be an "antitamper plug" afterall. It might be a
quick way to pass. You should however have your base idle CO reset with
a sniffer, or you may be able to do it as follows (works on later E28s
and E24s at least, not sure what other models it applies to):

Assuming a 15-pin diagnostic connector, use pin 5 in the diagnostic
connector and a voltmeter (a decent analog meter works best, unless you
have a digital meter that can do averaging).  If you hook the voltmeter
to this pin (actually it's a socket) and ground, you will get a voltage
reading the fluctuates between 0 and 12V every second or two. When the
CO is set properly, the fluctuation is perfectly even, like a pendulum.
As the mixture becomes rich, the needle will hang out more and more at
0V until  it just stays there when very rich. As it gets lean, it does
the same thing at 12V. So you just warm up the car, hook up the
voltmeter (do not unplug the O2 sensor) and turn your bypass screw on
the AFM until fluctuation is even (tighten screw = richer). I was able
to get the exact same setting within a fraction of a turn of the screw
as my mechanics did with an analyzer. Normal screw setting range seems
to be 4-6 turns out from full tight

Todd Kenyon 88 M5

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