Problem Logging Rear O2s...

[TFZ_Z06]

Not sure if I have found an error in the software or not but:

I thought we were supposed to be able to view the output for SAE.O2S12 and SAE.O2S22 as MILLIVOLT and % contribution to STFT. When I log this data, I get "N/A" as the result.

On the other hand, I am able to log GM.HO2S11, HO2S12, HO2S21, and HO2S22 with no problems.

Ideas?

[mr.prick]

Are they unplugged? :hihi:
I don't believe the rear O2's have an effect on STFT or LTFT.

[ScarabEpic22]

Rear O2s are simply a rationality check for the PCM to see if the cats are doing their job properly. They do not effect fueling as far as I can tell or have heard from the pros.

[TFZ_Z06]

By SAE definition, mode 2, PIDs 0x15 and 0x19 are used to pull 2 bytes of data. Byte 1 is the o2 sensor voltage and byte 2 is the STFT associated w/that sensor. If the sensor is not used in the calculation, a value of 0xFF is returned.

Incidently, about 8 years ago, I wrote a datalogger using a B&B cable for this purpose. I thought I had logged this same data at the time.
My source for programming was the 1999 Edition of SAE--On Board Diagnostics for Light and Medium Duty Vehicles, Standards Manual.

UNFORTUNATELY, the only software avail at the time was LS1 Edit which had no datalogger.

Its been a while and I may be wrong, but if anyone else has knowledge on this matter, please post up.

Again, is the PID mentioned supposed to work for my processor?

[TFZ_Z06]

Are they unplugged? :hihi:
I don't believe the rear O2's have an effect on STFT or LTFT.

Its not beneath me to leave stuff unplugged...but in this case, they are definitely plugged up :online2long: Its possible it was my FORD :fluffy: truck I logged. Its been a while...

[joecar]

The rear O2's may contribute to STFT's in some very special cases (I don't remember but it might be if the front O2's have failed and some other condition, and only for some OS's)...

but otherwise they don't.

Those pids may not be valid for your PCM.