40 mpg s10 2.2L

[JRMichler]

At part throttle, the fuel system runs about 14.6:1 fuel air ratio. At wide open throttle, that increases to about 12:1. The increased fuel is good for power and knock, bad for gas mileage.

If your rear axle ratio is too high, forcing you to drive at WOT, you can get worse mileage. That's why the comments about needing LRR tires and aero mods to run a taller rear axle ratio.

On the Ultragauge, look for a display of OPEN/CLOSED LOOP. Closed loop is the leaner economy fuel air ratio, open loop (with a warm engine) is the power ratio.

[Georgboy]

Delta camshafts are the guys I used for my XFI regrind, seems to be a good company.... I hope I get the 15-20 mpg increase they said they betted I would see bahahahahahah!! I would use them again. Figured you can do it on a metro, then others engines should be close to the same...

[Olympiadis]

The OBD2 systems I have worked with will stay in closed-loop during a WOT pass, though the adaptive fueling is put on hold until the PE flag is turned back off.

I haven't worked with everything out there, - mostly Chevys actually, but I wouldn't really trust the O/L - C/L flag to determine fuel enrichment.

You may be able to coax your ALDL reading software to look for the PE flag if you know the memory location and bit postion. It's just all-around easier for me to just watch either a real AFR meter, or display the commanded AFR on your data display.
When in any sort of fuel enrichment you will see it via the commanded AFR.
I think the DashCommand app displays commanded AFR for most vehicles.

Best bet is to test out what you've got and how it reacts. There are lots of little differences between the calibrations of different models. I don't really trust any of them because I've been jaded. lol

[Olympiadis]

Originally Posted by Georgboy

Delta camshafts are the guys I used for my XFI regrind, seems to be a good company.... I hope I get the 15-20 mpg increase they said they betted I would see bahahahahahah!! I would use them again. Figured you can do it on a metro, then others engines should be close to the same...

Regrinding is a good way to reduce duration and widen the lope separation a bit.
Changes in lift don't really have a large effect on MPG unless it goes so high that it causes a temporary stall in air flow which reduces velocity.

A performance valvejob will increase signal in the intake port and increase velocity. More flow with same size port = higher velocity. That's a plus for boosting up low RPM power.

[Georgboy]

Gotta love some port velocity and volumetric efficiency ...

[gmcZ]

Im getting 28 mpg now starting to see results!