Two O2 probes, one pre, one post cat???

[Bob Tom]

At 04:57 PM 1/9/01 -0700, you wrote:
>Well--yes it does. If you remove the converter--leave the second O2
>installed, it'll run the fuel system lean. The first O2 will swing rich
>lean--and the PCM will adjust AFR to keep the 'verter"burn" going. That's
>how the programming was done to eliminate an air pump.
>
>The second O2 is monitoring the burn, right ?? If the burn isn't
>correct--the system keeps cutting back fuel, less and less fuel--until the
>BL's are in the 155 to 160 range. It may not set a code, but it'll
>definitely be in the lean side...BTDT.
>
>Not trying to start another flame war <G>... but this is the end result.
>
>Lyndon

You may be correct, Lyndon.  It's something that I'll have to try and find out
about ... at least, for the Dakota PCM.  I know when I was testing a customized
PCM with 24# injectors (stock are 19#) with my scanner. the first O2 sensor
was showing outputs swinging back and forth but, after about 10 min. of
driving, the second one gave a constant rich output while the first still kept
fluctuated rich/lean.


Bob Tom       Burlington, Ont., Canada
'97 CC Dakota, 5.2L, 4x2, auto., 3.92SG, 4,265 lb (racing weight)
Dyno:   231.2 rwhp                340.0 lb-ft rwtorque
PB:      14.737 @ 91.75         9.364 @ 72.95

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