Manipulating Closed Loop AFR

[mistermike]

I'm running a shade rich in closed loop, possibly due to the headers causing lower NBO2 temperature. I'd like to lean it out a bit. I've tried incrementally lowering the O2 switch point without much luck. I've gone as low as 400 mV to no avail. Interestingly, if I raise the switch point, it has no problem going richer. Are there any other techniques for tweaking the AFR slightly? I know I can command any AFR I like in the RPM/kPa/AFR table, but I'd prefer to have the NB's control it.

[mistermike]

Bump 8)

[GMPX]

Go lower, go down to 200mV and see what happens.
A good test is to log a WBO2 and the Std O2 to get an idea on what WBO2 value equals the NBO2 voltage at the same ponit, eg, WBO2 = 15:1, NBO2 = 235mV, the PCM should then try to swing around that AFR.

Cheers,
Ross

[mistermike]

Great Idea! I'll park them in the same section of the chart. That should make it very easy to compare. I was hesitant to go below 400 without asking around first.