What is everyone seeing as far as fuel trims in DFCO? I thought they were supposed to lock at zero, but that's not the case in my car. The injector pulse width zeros, but the fuel trims shoot positive (roughly +10!!), which leads to a slight rich spike when you get back on the gas. Now, assuming that the fuel trims are NOT supposed to zero out in DFCO, i would tune the coast down table to correct this right?

Actually looking through some other car's logs, it looks like some zero out fuel trims in DFCO and some don't, so i'm thoroughly confused what affects it.

Mine does that, and mine takes a good 4-5 seconds to enter dfco, didn't used to do that.

I think it shoots rich because your map is bad, mine goes the other way, but my car dips rich before dfco comes in, still working on tuning that out.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Hmmm, last log i did i was getting the full range of the map sensor (logged 18-104kpa), and i'm not throwing any codes or showing any other symptoms of a bad sensor. DFCO is definitely working - IPW goes to zero, just not sure why there would be a fuel trim when there is no fuel. And why it's different on some cars vs others.

Bring up the status bit and and watch it while you drive. It may be jumping way lean without going into dfco.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

I can try that, but ipw = zero. That can only happen in DFCO or if the car is off lol.