AFR on a 2002 chevy malibu

[jgammon1979]

I'm trying to increase my fuel economy on my 2002 chevy malibu. Right now, my AFR is set to 14.7. Is it possible to lower this number and run a little leaner to increase my fuel economy or is there a better way to increase my fuel economy on my car with stock engine and no aftermarket stuff.

[Red Racer]

Where are you at right now with mpg? Did you try changing the spark tables as well (possibly in combination with a slightly richer mixture). Also try running in OL and average your O2 voltage at 14.7 commanded. I did this and noticed by the average my engine actually runs at about 14.4-14.5, probably due to the 'up to 10% ethanol' in the fuel for our area.

[oakleafresin]

You need access to the rich/lean thresholds for the narrowband and HPT doesn't have these mapped, if you want to lean out your cruise a little. It's a waste of timing running lean though, you won't pick up much, if any, mpg. Most of it will come from timing. On pump gas, you want to run +/- 40* in the lower airmasses. Slightly more might be possible depending on your car/mods/gas.

[Perforator]

If you want to increase your fuel economy lowering your afr is not the way to do it. You want to raise it.

[murphinator]

timing at cruise.... specifically where you cruise primarily , especially if your commute is at a steady speed.

open up your timing histogram and watch which cells you are in the most and concentrate your efforts there , cell count can be helpful too to see which cells you stay in.

the cells where you are at low load or coasting will tolerate a lot of timing , the low rpm high load cells you hit starting up a steeper grade wont take nearly as much

you will be amazed how little you have to press on the pedal to go up a slight grade at speed once you get timing optimized and it will increase your mpg , I routinely averaged 30 when I commuted 2 states away 6 days a week and tuned timing this way

my commute was 95% route 95 at 72/73 mph and on occasion I would go 15 min out of my way to the track 1/2 way home and run mid 13's on the same tune that got me 30mpg this was with one of my 3800 sc regals