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2000mc · 06-30-2019, 12:48 PM

I don’t have much Ford specific experience, mainly Gm. A lot of vehicles seem to be able to adjust the long term fuel trim +/- 25% and short term +/- 25%. Problem is I think most will set a rich or lean code once the long term is off 20-24%. So the vehicle may be able to correct 50%, you may be stuck with a check engine light if you’re holding over 20%. It may be fine, aside from the light, while in closed loop, but I’d guess you’d be dumping extra fuel whenever you’re in open loop. Making the change for mileage, I’d be scared of going to a higher flow.

06-30-2019, 12:48 PM	#2 (permalink)
2000mc herp derp Apprentice Join Date: Oct 2008 Location: Lawrence, KS Posts: 1,049 Saturn-sold - '99 saturn sc1 Team Saturn 90 day: 28.28 mpg (US) Yukon - '03 GMC Yukon Denali 90 day: 13.74 mpg (US) Thanks: 43 Thanked 331 Times in 233 Posts	I don’t have much Ford specific experience, mainly Gm. A lot of vehicles seem to be able to adjust the long term fuel trim +/- 25% and short term +/- 25%. Problem is I think most will set a rich or lean code once the long term is off 20-24%. So the vehicle may be able to correct 50%, you may be stuck with a check engine light if you’re holding over 20%. It may be fine, aside from the light, while in closed loop, but I’d guess you’d be dumping extra fuel whenever you’re in open loop. Making the change for mileage, I’d be scared of going to a higher flow.