Faster tuning method for VE

[brianw21]

I have been working on a heads and cam this week, and came across what I though would be a good idea, and sure enough it helped.

My tuning method for VE:

1. Set MAF fail to 0
2. Set up the AFR histogram (if you haven't already).
3*. Connect to the car, and under VCM control in the scanner turn off closed loop.
4. Start the car and do the normal driving around and logging.
5. Take the AFR% error and apply it to the VE table.

Step three was a change from everything I read here. My problem was that the STFT and LTFT (even when reset) would start to influence the AFR during the 30 minute loggin session. By forcing it open loop in VCM controls it will no longer apply LTFT and STFT while driving.

This meant that the AFR results were driven purely from the VE table and not influenced by STFT at all during the logging. So my results were MUCH more accurate.

This small change made a huge difference, as it only took two driving sessions to get the VE very close. Before the STFT were skewing the AFR results and I had to make repeated passes until the STFT were small enough.

[spoolin]

Very true, but if you do this just make sure to turn off CL every time you restart the scanner or the car. I think the guides just say to disable it in the flash so it is hard coded and you dont have to mess with it ever again unless you want to re-enable CL.

[brianw21]

But I noticed that even with the MAF fail causing open loop the LTFT and STFT were still influencing the fueling.

[spoolin]

But I noticed that even with the MAF fail causing open loop the LTFT and STFT were still influencing the fueling.

MAF Fail doesnt cause open loop. It causes the PCM to use the VE table instead of the MAF + VE table. By disabling the MAF, you are still running in Closed Loop (LTFT, 02 feedback) until you go into VCM Editor and disable LTFT and the disable closed loop enabler by setting it to its max value so it never goes into CL.

But your method works too. Its just a matter of setting it for good or setting it on the fly.

[Country Boy]

I like that idea. Wouldnt leaving it OL all the time be a problem?

[chrisj6]

You can disable LTFT and STFT in the flash, then you need to go clear your fuel trims after uploading this tune, also set the open loop enable temp to 284 and closed loop will never occur.

As far as turning off the MAF, all that causes the pcm to do is go into Speed Density mode and use only the VE table. Some people ditch the MAF and run SD tune all the time.

[TrekGTO]

I have been working on a heads and cam this week, and came across what I though would be a good idea, and sure enough it helped.

My tuning method for VE:

1. Set MAF fail to 0
2. Set up the AFR histogram (if you haven't already).
3*. Connect to the car, and under VCM control in the scanner turn off closed loop.
4. Start the car and do the normal driving around and logging.
5. Take the AFR% error and apply it to the VE table.

Step three was a change from everything I read here. My problem was that the STFT and LTFT (even when reset) would start to influence the AFR during the 30 minute loggin session. By forcing it open loop in VCM controls it will no longer apply LTFT and STFT while driving.

This meant that the AFR results were driven purely from the VE table and not influenced by STFT at all during the logging. So my results were MUCH more accurate.

This small change made a huge difference, as it only took two driving sessions to get the VE very close. Before the STFT were skewing the AFR results and I had to make repeated passes until the STFT were small enough.

Can you expand on this for a new guy
1 are you saying in editor set MAF fail high to 0 and MAF fail low to 0 save and flash VCM?
5 Take the AFR% error and apply it to the VE table? Is there a function or formula for this?
05 GTO 6sp

[Bill@HPTuners]

keep in mind dfco guys as well...for the 2 or 3 minutes it takes to setup the file why not just do it that way rather then through the bi directional controls & have to set that up each & every time...not to mention you'd always need your laptop on.

[WS6FirebirdTA00]

keep in mind dfco guys as well...for the 2 or 3 minutes it takes to setup the file why not just do it that way rather then through the bi directional controls & have to set that up each & every time...not to mention you'd always need your laptop on.

yeah, I would not recommend tuning the way mentioned.Spend the minute it takes to turn off DFCO, CL, LTFT, STFT in the tune. You have to set the MAF frequency to 0 anyway so make the extra clicks. Not only that but you want to change the OLFA table as well.

[TrekGTO]

yeah, I would not recommend tuning the way mentioned.Spend the minute it takes to turn off DFCO, CL, LTFT, STFT in the tune. You have to set the MAF frequency to 0 anyway so make the extra clicks. Not only that but you want to change the OLFA table as well.

Sounds good to me wish I could figure it out. What should I Include and Delete in Histogram for my new wide band? Is there a secondary VE table on 05 GTO I dont see one?

[Bill@HPTuners]

Sounds good to me wish I could figure it out. What should I Include and Delete in Histogram for my new wide band? Is there a secondary VE table on 05 GTO I dont see one?

no secondary VE since 2000.

as for what to include or delete its up to you. Afr commanded is a good addition to whats in the default config...im sure there are LS2 configs floating around in this section though that you could us...also remember TPS SAE wont show 100% throttle...you'll need to log ETC position.

[SideStep]

keep in mind dfco guys as well...for the 2 or 3 minutes it takes to setup the file why not just do it that way rather then through the bi directional controls & have to set that up each & every time...not to mention you'd always need your laptop on.