WB vs STFT Tuning. WB Confusion

[ltdriser]

I just gave it a crack at tuning with WBO2 sensor only tuning, first time with one. I started with VE then went to MAF. For the most part my WB was reading a lean condition on the 4 runs I did so I kept bumping up my air values. I believe I had all of the closed loop stuff turned off, my logger said OL-NotReady. I did this by disabling the LTFT and bumping the closed loop enable ECT up to like 284. I was plotting the EQ Ratio Error histogram for my VE and MAF tables. I never really got the values super close but I could tell about half way in this wasn't going to work for me. I went ahead and finished out just for the exercise. I then put everything back in closed loop and just like I had suspected my car was insanely rich. The fuel trims were in the -20s. Am I missing a key fundamental here? I got the WB because everyone said its the right way etc, it seems to have me way more off course than just STFT tuning.

1. Disable Closed Loop via ECT
2. Disable LTFT via ECT
3. Disable DFCO via ECT
4. Disable COT

For VE only I set MAF fail to 1 hz. For MAF only I set VE disable to 300 rpm.
One thing I'm curious about. I have the WB on a tailpipe sniffer, is that that big of a problem? I do have high flow cats. I didn't think it'd be an issue because when I had the car dyno tuned the tuner did the same thing for AFR logging.

[5FDP]

Put the wideband in one of the primary o2 sensor ports. Having it so far away and after the cats is not good for steady state tuning. At WOT the high end tail pipe widebands work okay because there is tons of exhaust gases coming out at once and the cats can't really do their job at full throttle.

Also that logs shows your short term fuel trims are still active, you can't have that happen. It's throwing everything off. You need to use the VCM scanner prior to logging to reset the fuel trims and disable the fuel trim learn.

Don't forget to set the MAF dtc's to MIL on first error too. And try to make it so the computer is commanding stoich almost all the time, make it so PE can't be enabled so easy. Raise the rpm delay or throttle percent way up to like 80-90%. Don't forget about any cat test or rear o2 sensor test if that computer has it in the engine diags exhaust tab.

[gottogo]

I was going to say "are you clearing your fuel trims?"

But what he said is good too.

[ltdriser]

I was thinking that even though it showed the STFT I was still in OL and they wouldn't applied. Am I wrong to think that? Also, I shouldn't have to clear STFT right? I have LTFT off but I thought STFT cleared themselves every start cycle. What does MAF dtc to MIL on first error do? I thought just 1 hz was enough. I'm still new, so many question!

[5FDP]

Many calibrations use short term trims in open loop. That is why they must be disabled within the calibration or with the VCM scanner prior to logging your data.

The MAF sensor has diagnostic trouble codes, you have to fail the MAF sensor by setting the high fail to 0hz or 1hz, it doesn't matter and by setting the error codes to MIL on first error. You won't truly know if it's in speed density unless code P0103 is a current code and if you were logging the MAF sensor status it would say failed.