After installing my Scanmaster I noticed one Bosch O2 sensor acting wierd. You guys informed me that the one not bouncing around a whole lot was the problematic one.

The parts house replaced them for free but this time I went with the GM Delphi O2 sensors instead. They even look more robust than the Bosches.

They are now installed and they behave the same in terms of their readings, they bounce around all over the place at idle and remain rather steady at WOT.

Once I went out and hammered on it, I noticed at WOT they were both about 880mv. After firing on it some more they hung around the 860mv point then began to creep back up to 880mv.

The left and right BL's at WOT were 128. The left and right intergrators were also 128 at WOT.

I seem to have very little knock retard, a couple times it 3-4 but for the most part it remained at 0. There seemed to be no pattern to getting knock retard

Does all this sound good?
Does my A/F mixture seem good?
Am I checking my intergrators and BL's wrong at WOT, should this be lokked at while idling?

Thanks
Bill

 

bump

 

Have you read my online ScanMaster guide? All of your questions are answered in there:

http://members.aol.com/InjuneerZZ/ScanMast.htm

The stock narrow-band O2 sensors are smiply not very accurate at the A/F ratios used in WOT. The readings will change significantly with the temperature of the sensors, masking true changes in voltage readings due to A/F ratio changes. At best, they are only "rough" guides as to WOT A/F ratio. Your's don't sound bad, but you have to recognize the limits of narrow-band sensors. They are only accurate over the narrow range of 14.7:1 +/- 0.10.

There are 18 different "Cells" for the BLM's, representing various combinations of engine RPM and engine load (as represented by MAP). You need to find the BLM's for each cell, and that's difficult with the ScanMaster, since you have to be viewing the BLM (first left, then right) and quickly cycle the ScanMaster to the "CEL" display. Its a lot easier with a data logger.

The boundaries and functions of the various Cells are described in my writeup.

Your WOT BLM's will be dependant on the closed loop BLM's. Short version.... if your BLM's at high load are "adding" fuel (above 128) in closed loop, the PCM will use the BLM's from Cell 15 at WOT. If the BLM's were "subtracting" fuel (below 128) in closed loop, the PCM will either lock the Cell 15 BLM's at 128, or default to Cell 18 and lock the BLM's at 128. Sounds like yours was subtracting fuel and locked them at 128. Find the BLM's for Cell 15.... they will probably be less than 128.

The short-term fuel corrections (INT) will always be 128 at WOT, since there is no feedback loop being used by the PCM, and learning is disabled. Technically, its not even called "WOT", but rather "power enrichment" (PE) mode.

 

Thanks for the response.
I have reviewed your document, it was very useful.

The AF mixture related material will take some time to digest due to its complexity.

I feel good that I have made some progress by replacing the bad sensor.