omega552003

Ok so im wondering what the "Fast (Left/Right)O2 Threshholds" table is for. I can only think of 2 things

1: Compensate for the uneven airflow in the Intake Plenum.(I highly doubt because the PCM is looking for the ratio not volume)
or
2: What the O2 sensor needs to read for based on its position in the exhaust for the PCM to see the desired value.

I'm only asking because the Long Tubes have the sensors farther back from the exhaust ports than the stock manifolds did. I'd think that would change what the sensor reported to the PCM.

So with long tubes should i adjust each bank's tables to be equal (stock tune they are different)?

bobdec

Those voltage thresholds are your rich/lean settings. They vary by engine temp and are used to determine the fuel trim zero percentage (BLM 128 in OBD1) sweat spot for fueling calculations. Normally an O2 switches between 100-900 Mv from lean to rich those 4XX Mv thresholds are correct O2 AFR mean voltage targets. Once the O2 reaches 600* F it will switch correctly even if the O2 is in a different spot, it's the high temp that requires them to be close to the engine. The O2 threshold voltages should not need changing as long as they are hot. Altering the settings may actually effect what the PCM sees as stoich and can mess up other calculations.

omega552003

I'm still a little fuzzy on this. why bank 1 is looking for richer O2 targets than bank 2. I would think that with o2 the same distance from the heads, that the targets would be the same.

Right Fast O2 Rich/Lean Threshold (mv) Vs. CL Mode Vs. RPM
RPM______________CL Mode
____ _0_ _8_ _16 _24 _32 _40 _48 _56 _64
0___ 365 392 392 392 413 500 544 457 457
200_ 365 392 392 392 413 500 544 457 457
400_ 365 392 392 392 413 500 544 457 457
600_ 365 392 392 392 413 500 544 457 457
800_ 365 392 392 392 413 500 522 457 457
1000 365 392 392 413 435 457 479 457 457
1200 365 392 392 435 435 435 457 435 457
1400 365 392 392 413 426 435 435 413 413
1600 365 392 392 392 413 435 413 392 392
1800 365 392 392 392 413 435 392 392 392
2000 365 392 392 392 413 435 392 392 392
2200 365 392 392 392 413 435 392 392 392
2400 365 392 392 392 413 435 392 392 392
2600 365 392 392 392 413 435 392 392 392
2800 365 392 392 392 413 435 392 392 392
3000 365 392 392 392 413 435 392 392 392
3200 365 392 392 392 413 435 392 392 392


Left Fast O2 Rich/Lean Threshold (mv) Vs. CL Mode Vs. RPM
RPM______________CL Mode
____ _0_ _8_ _16 _24 _32 _40 _48 _56 _64
0___ 365 435 435 435 457 500 522 435 457
200_ 365 435 435 435 457 500 522 435 457
400_ 365 435 435 435 457 500 522 435 457
600_ 365 435 435 435 457 500 522 435 457
800_ 365 435 435 435 457 500 522 435 457
1000 365 435 435 435 479 500 522 435 457
1200 365 435 435 435 457 479 500 457 457
1400 365 435 435 426 457 479 479 457 457
1600 365 435 435 418 457 479 479 457 457
1800 365 435 435 418 457 479 479 457 457
2000 365 435 435 418 457 479 479 457 457
2200 365 435 435 418 457 479 479 457 457
2400 365 435 435 418 457 479 479 457 457
2600 365 435 435 418 457 479 479 457 457
2800 365 435 435 418 457 479 479 457 457
3000 365 435 435 418 457 479 479 457 457
3200 365 435 435 418 457 479 479 457 457

CL Mode Vs. Mass Air Flow
gm/s ___CL Mode
_0 ____0
_4 ____4
_8 ___16
12 ___30
16 ___36
20 ___40
24 ___44
28 ___50
32 ___54
36 ___64
40 ___64
44 ___64
48 ___64
52 ___64
56 ___64
60 ___64
64 ___64

bobdec

Sorry just noticed you are a '97 OBD2.. I get caught on that to often. My response was for OBD1 where the L & R bank voltages are the same, also the CL Mode table does not look at RPM and the CL mode values are sort of linear 0 through 64) starting at 0 CL mode for 0 AFGS up to 64 CL mode for 64 AFGS. Been thinking about OBD2 and don't have an answer on why the OBD2 LT1 voltages vary 14% between sides. That's a big difference and something that I would like to get answered also.

omega552003

well the numbers translated to afr are really damn close like 14.3-14.9, so its almost negligible, not to mention the engine is only using the table at light throttle