Does anyone else notice that their cars/trucks will sometimes have "good days" where it runs strong and responsive, and then "bad days" where it's sluggish and seems to want a little more pedal to do anything?

Well, if not..I do.

I've been running around with DFCO disabled for a few months now. RPM settings up around 6,000 or so. The thing has been running mint.

This last weekend I turned it back on, thinking that my tuning (SD tuning) was coming to a close for now. These last few days, the truck has been having a few "bad days". I look at my logs, and where DFCO is 'closing out', my fuel trims go wacky -- LTFT's are +3 to +4 and some +5's, while normally everything is 0, -1 and some -2's.

FTC 1 and 2 seem to be effected. I understand these are deceleration and very light throttle, correct?

I turned off DFCO, and reset the fuel trims - the engine has been running nice and crisp again.

Anyone else having problems with DFCO? I don't mind leaving it off - Just wondering.

 

I'll bring this post back from the dead. I was thinking about this after i have been fighting with my trims over the last few days. For some reason on decel my trims jump up now that my MAF is plugged back in. I think that DFCO is partially there because of some funky MAF issue on decel. The MAF reads airflow, but on decel it shows the same frequency, but has different fueling requirements. I also think that this is why my bucking came back when I plugged my MAF back in.