awilson40

I've been searching and see lots of different opinions.
What is a safe, economical AFR for interstate cruising.
Something that wont affect driveability or burn valves ?
BTW, I run off ROW maps which ignore the O2 sensor

I'm at 15.0 to 15.2 :1 and getting about 25 mpg

Chime in everyone
Thanks

toddk911

Well, I have read numerous posts in here that say as long as you are not on boost, you are an NA motor basically which would mean 14.7 -15 would be safe.

lee101315

Is 16:1 or 17:1 ok when cruising? I assume fuel economy would increase slightly....

PorscheDoc

I tune for right around 15:1 as well at cruising. Got 25mpg this weekend when we went to renntreffen, so it was a mix of normal cruising (running about 90 with an S2 gearbox).....and occasional full throttle passing, lol.

Quickbeam

Are you guys running without the narrow band? I ask because I don't see how you could get 15:1 in closed loop unless you're modifying the maps on the chip.

awilson40

I select the ROW fuel maps from the region plug which doesnt use the o2 sensor.

Rogue_Ant

15:1 is fine for cruising / low-loads.

I've ran ~16.5-17.0:1 on gas; however, that lean needs more timing advance, and disabling the O2. The combination of lean and added timing willl give good mpg results.


-Rogue

awilson40

Outstanding
Thank you for all the coments

PorscheDoc

Running a maf with piggyback.

INURGRL951

Ok when you are cruising it is safe to run even up in the high 17ish on a/r but you have to understand as soon as there is an increase in pedal effort the a/r has to drop. Just to give you a round about at 5psi vacuum around 13.7-13.3a/r. At 0psi 13.3-13.0 a/r. At 10 psi boost 12.7-12.2a/f. From 15 psi of boost 12.2-11.8 a/f is good and over 18psi you need to be around the 11.8-11.4a/f( I know this one kinda rich but that's how I like it) and on these number would be on mild to WOT when your tuning it. But to get back on track if you are in those areas on boost (where it's important the "cruising" a/r can be like I said at the beginning as high as the the upper 17 ish.

TurboTommy

On our engines, as lean as 17's will make it run/cruise rough; a little stumbly or tiny bucking, almost like you're driving on a bit of a bumpy road.
I also prefer to run without the O2 sensor and am able to adjust air/fuel to a small degree. When I get into the 16's I definitely notice cruise smoothness going south. If I was able to adjust timing in those areas, I could probably remedy that somewhat, but I can't.