2007 5.3 Swap- Open loop MAF tuning- STFT's causing AFR's to cycle back and forth..

[Grip]

In a track day car. No dyno, not street leagal to drive around. Just trying to get it close and safe to go to the track. I noticed that when doing an idle log and trying to dial in the MAF calibration that the STFT's kick in and cause the AFR's to go all over the place.

Any ideas?

[Grip]

Do I just need to dial the MAF calibration table in better in that area it is idling?

[schpenxel]

Yes it needs to be dialed in better. It's 10-15% off

[scottt28]

Do I just need to dial the MAF calibration table in better in that area it is idling?

Did you purposely set dynamic airflow below idle speeds?

[scottt28]

@ 3000 hz, I see about 9.5 fat, and @ 3150 hz, I see an 11.7% error. Is that what you're referring to schpenxel?

[schpenxel]

Something like that, don't have the log open anymore but whatever the fuel trim values were going to is how far off it was.. I think it was 15% or so

[Grip]

Something like that, don't have the log open anymore but whatever the fuel trim values were going to is how far off it was.. I think it was 15% or so

So this is where I am confused, I see the STFT's subtracting a ton of fuel and the AFR's reacting. I just don't know why it is going so FAT. I'm commanding 13.5. When I was graphing AFR error and copy/pasting that info into the MAF correction table, it is no consistent. Should I be doing the same but using the data from the STFT+ LTFT info?

[schpenxel]

Reduce MAF table if it's richer than commanded..

I would put it in closed loop and use fuel trims instead of trying to use AFR error for part throttle areas personally

It's going in and out of closed loop for whatever reason so that's why AFR is bouncing around like that

[Grip]

Thank you! Any idea why it would go in and out of closed loop? I am trying to force it into open loop. All of the logging, so far, has been at idle. No part throttle yet.

[schpenxel]

Not sure why it was going in and out of closed loop like that. I'd just put it in closed loop personally and let fuel trims do their thing for idle/part throttle.

[Grip]

We figured out how to make the STFT's stop. I guess I need to drive it now and log some part throttle. Can anyone explain the advantages to logging the AFR err in open loop vs, fuel trims in closed loop? Also, what to do with the data after logging fuel trims. I understand how to use the chart data from logging AFR error.

Thanks!

[schpenxel]

Different strokes...

For me every time I tune something in open loop when I put it back in closed loop fueling fuel trims end all off some still anyways, so it's easier to just use fuel trims for part throttle and be done with it

Plus you don't have to deal with fueling being way off. In closed loop the computer will make the corrections for you then spit out values for how far off it was (i.e., fuel trims)

Either way can work fine.

[Grip]

Different strokes...

For me every time I tune something in open loop when I put it back in closed loop fueling fuel trims end all off some still anyways, so it's easier to just use fuel trims for part throttle and be done with it

Plus you don't have to deal with fueling being way off. In closed loop the computer will make the corrections for you then spit out values for how far off it was (i.e., fuel trims)

Either way can work fine.

Do I just copy and paste those values into the VVE table? How do I know what to modify with those values?

[schpenxel]

How do you know what to change when tuning open loop? Same thing basically but you're using fuel trims instead of AFR error