resistor on Os sensor

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

Jk writes:
>
ps for those with older Motronics, here's a simple way to richen up the 
system. I recall you can put a resistor in the line with the O2 sensor 
signal.  That fakes the computer to thinking you're running leaner than 
you are.  So the ECU richens you up slightly.
     If anyone recalls the value of this resistor, please post it.

>

Er - that would be the coolant temp sensor. Putting a resistor on the O2
sensor would simply reduce the current from the sensor, so the ECU would
not detect the sensor and hence operate in open loop. Just unplug the
sensor if you want to do that. Some 80s cars ran too lean during open
loop warmup. A quick fix was to add a resistor inline with the coolant
temp sensor - more resistance=ECU thinks engine is colder than it
is=richer mixture. This was later fixed by changing the coolant temp
sensor part#. This of course would only work in open loop (warmup or
unplugged O2 sensor) since the ECU would correct the mixture in closed
loop, unless it was stupid rich in which case it would revert to the
onboard maps (open loop).

Todd Kenyon 88 M5

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