There seems to be allot of methods to tune the AFR on the V6 cars. Since these cars don't yet have an open loop table like the V8's and the V6 (4.3) trucks, the commanded AFR while in open loop is all over the place when not in PE. In PE the commanded AFR will be were you set it.
This is what I found is the best way to tune these cars. First leave the VE table stock. Then zero out the Power Enrichment PE Enable > Delay vs. TPS table (some models will already have this table zeroed out). Set the PE Enable TPS > Hot to 0% (at all rpms). Set the Base AFR vs. ECT to 14.7 at all temps. Zero the Add vs. Tps (note the values in this table add to the Base AFR vs. ECT and leans the AFR). Then zero out the Add vs. Rpm table.
Now install the wideband in place of the stock front 02 sensor, or the right front if a rear drive car (this will put the car in open loop). Flash this new file, then warm the engine to operating temp. Start scanning and reset the fuel trims. Now the commanded AFR will be steady at 14.7. With the Maf AFR histogram open, drive the car at part throttle to fill the histogram up to ~7500 hz. Try to accel & decel smoothly. Then copy & paste the Maf error % histogram to the Maf table using paste special multiply by %. Once you get the AFR close to 14.7, then use paste special multiply by % - half. For the low end of the Maf table that you didn't enter, just enter the error % from the lowest airflow hz cell that you did enter. So by now the part throttle AFR will be ~ 14.7.
Now change the PE Enable TPS back to stock (or were you what it as some models have the low rpm enable at 100%). Change the Base AFR vs. ECT to 13.0 at all temps for NA, or 11.0 for a boosted engine. Flash this new file, connect the scanner and check & reset the fuel trims. Bring the car to a dead stop, use the VCM controls to put the trans in 2nd gear. Now go wot till your max rpm desired. Then copy & paste the Maf AFR error % to the 7625 hz & higher part of the Maf table. For the freq. hz cells that the scanner skipped over, just average these cells. For the higher freq hz cells of the table that you didn't enter, just enter the error % from the highest airflow hz cell that you did enter. Once you get the AFR close, use paste special multiply by % - half.
Unlike the V8's and V6 trucks, if the part throttle fuel trims are negative by even a small %, you could have negative LTFT at wot. This is why you need to get the open loop part throttle AFR close to 14.7 BEFORE wot tuning the AFR.
When going to wot from a dead stop there will be a lean spike at first (under 7500 hz) that is normal if you first got you part throttle AFR right, this is caused by the split sec. delay for the richer exhaust to reach the wide band.
Now install the stock O2 sensor. If you did everything right, your LTFT's should be close and will lock at 0% @ wot.
Russ Kemp