Re: Heater Fan Leans Out Mixture???

[DeWitt Harrison <de@aztek.com>]

On Mon, 07 Apr 1997 08:41:23 -0400, Glenn Lawton wrote:

>OK, so I've had a couple of days screwing around with
>the urq and the new boost, and I saw something weird 
>withe the Lean/Rich mixture gauge.
>[  ... ]
>ANYWAY, if I turn on the heater fan to warm up the
>cabin, the reading tends to LEAN, higher fan speeds
>yeild more and more LEAN. Why????????????

The main effect my fans have on the electrical system
is to drop a fair amount of voltage through connecting
wiring. My first guess would be that either the 12volt
connection or the ground for the gauge is associated
with the fan wiring (same feed circuit?). The gauge
measures the OXY sensor output but relies on 12volts
to power the gauge electronics.  The gauge must
translate OXY sensor output changes of only a few
millivolts into light segment changes; it needs to be
very sensitive. It's very possible that the gauge is also
measuring fluctuations in its supply voltage.

Put a voltmeter across the 12volts at the back of
the gauge and see if their is a correlation between
that reading and the gauge display.

DeWitt Harrison    de@aztek.com
Boulder, CO
88 5kcstq