DFCO for AutoVE

[foznoz]

In the tutorial on AutoVE tuning, it says to turn DFCO off. Why is this? Only reason I ask is that I don't like the way the car drives when it's off, so I'd have to turn it back on after tuning, so wouldn't that mess up the tune?

[Blacky]

If you are AutoVE logging and DFCO is active, the wide band O2 will see an extremely lean condition. That will severely skew the data in those cells - cells that may at other times be used to calculate fuel under light throttle.

After VE tuning, when DFCO is active, the injectors are shut off completely so it won't matter what is in the VE table at that point. ALL fuel calculations are completely ignored by the PCM when in DFCO - since the injectors are closed.

Regards
Paul

[SSpdDmon]

The other option is to leave it turned on until you get most of the table dialed in (if your not using real time tuning). Then, eliminate the data in the log with a filter that excludes data cells where timing is less than 7 degrees. The only down side is the lower MAP cells of the VE table will be wrong until you decide to tune them (no DFCO).

[lplott]

Looking in the tutorial for AutoVE, the only mention of DFCO is on page 6, Open calibration {B3313} "DFCO Temp Enable" and Set to 122 degree C.

I do not see where DFCO is turned off or back on?

Am I missing something?

Lonnie

[Chevy366]

Looking in the tutorial for AutoVE, the only mention of DFCO is on page 6, Open calibration {B3313} "DFCO Temp Enable" and Set to 122 degree C.

I do not see where DFCO is turned off or back on?

Am I missing something?

Lonnie
122c disables DFCO , temp has to reach that value , which it should never do .
You just have to remember to reset when finished .

[lplott]

This is probably where my surging at very mild deceleration is coming from.

What should the "normal" value be?

Thanks,
Lonnie

[Chevy366]

This is probably where my surging at very mild deceleration is coming from.

What should the "normal" value be?

Thanks,
Lonnie
I do mine in F* so 104* for me (252* disables) .

[lplott]

Thanks. 104*F=40*C

This may be the long lost cure to my surging at very mild deceleration.

Lonnie

[hquick]

Lonnie, did turning DFCO back on fix your slight surging?
I'm getting the same thing.

[lplott]

Been working too many hours to plug it in. Will do it tonight and let you know towmorrow.

Lonnie

[lplott]

hquick,

Reprogrammed B3313 back to 40c and drove to work this morning. Much smother with and without cruise control. I would say 99% of the surging under deceleration is gone.

Been fighting this for a long time, now will have to go back to a basic tune, start all over, and do it right without all the other twiks I have tried to get rid of the surging.

Good luck,
Lonnie

[hquick]

Thanks Lonnie.

Are you going to AutoVE with B3313 set to 40oC?

[lplott]

No, B3313 needs to be turned off (set to 122c +) during AutoVE to keep it from sending a lean spike into the BEN table, both Main and Boosted, when declerating.

B3313 will just be one of those things that I/we have to remember to set/reset when we are tuning and done tuning.

I will ask Blacky to edit AutoVE Tutorial, page 6, step 5, to add in RED, "Be sure to reset B3313 back to 40c when AutoVE is completed. This will allow DFCO be be enabled during non-tuning driving and prevent some decleration surging."

Give it a try and let me know if it works for you also.
Lonnie

[hquick]

Thanks again...that's what I thought you meant.
It's 1.45am here and I'm not thinking straight. Lol!
I'll give it a go.

[lplott]

Update: drove 50 miles this afternoon. Still minor surging in lower RPM (idle-1200). Very minor and drives out of it, which it wouldn't do before. Will have to log all spark modifier data to see what is causing it. If I find anything, I will update.

Lonnie