RB25 AFC-Neo AFRs/Settings (Crusing) - GURU NEEDED

[240Raver]

Just curious to know what a safe good AFR reading would be while NOT under load just cruising around the city/freeway.

I got my RB25 tuned today (street tune) and would like to know if I'm able to run anymore lean than what it is as I'm going for maximum gas mileage with still being SAFE. Mind you I barely use about 10% throttle when driving anywhere and hardly never step on it.

SETUP: S1 RB25, Greddy IM, FMIC, Boost @ 10psi, Aeromotive FPR, Z32 Fuel filter, 3" From turbo back, walbro fuel pump, HKS bov atmospheric, AFC-neo

My AFR's while cruising are about 14.7-15.2. I was just curious if I could go leaner.

I mainly went so I can get a low throttle tune as I mostly do city driving and barely use like 10-15% throttle all the time. For some reason a 0% low throttle to me looks odd as of we weren't tuning for normal cruising. Most of the time I was just flooring it (WOT).

AGAIN, I went in for a tune STRICTLY for better gas mileage. Someone with SAFC knowledge please chime in.


My settings

LOW THR - 0%
HI THR - 45%

NePoints (HI / LOW)
500 (-2 / +15)
950 (-2 / +15)
1500 (-2 / +15)
2000 (-2 / +5)
2500 (-2 / +2)
3000 (-2 / +0)
3500 (-2 / -2)
4000 (+2 / -2)
4500 (+2 / -2)
5000 (+2 / +0)
5500 (+1 / +0)
6000 (-3 / +0)
6500 (-3 / +0)
7000 (-3 / +0)
7500 (+0 / +0)
8000 (+0 / +0)

Thanks for the help!

[Carl H]

looks fine but honestly no need for an afc with a stock neo computer, the fuel trim authority its pretty crazy and it will lean its self out to high 14's if all is right.
dont want to go much leaner as you'll get nasty lean stumble and it boosts egts through the roof.
as the safc is an interceptor you cant fine 'tune' as the high and low throttle switches between an effective two 'maps'...bandaid fix at most.

[240Raver]

looks fine but honestly no need for an afc with a stock neo computer, the fuel trim authority its pretty crazy and it will lean its self out to high 14's if all is right.
dont want to go much leaner as you'll get nasty lean stumble and it boosts egts through the roof.
as the safc is an interceptor you cant fine 'tune' as the high and low throttle switches between an effective two 'maps'...bandaid fix at most.

Thanks for your reply I appreciate it. I'm just trying to go as lean as possible to get the best fuel economy. With my 14.7-15.2 AFRs while cruising I only manage to see 200miles to a tank in my S14 and I drive like a granny.

What would you recommend to get for tuning for partial throttle so I get better gas mileage than I am now? I'm pretty much stock and don't plan on upgrading my turbo or injectors at all. Would you recommend going NIStune? I don't mind WOT tuning to be honest I never hit WOT.

[Carl H]

if you're only getting 200 to a tank then something is seriously wrong with your setup...even with my 30 and crap cruise afrs (13:1) i still get 264mi/tank.
you should check the base timing on your motor as that will make or break a car.

an rb20 in good shape with everything set properly will get 28mpg highway, and its a 'sloppier' ecu compared to the neo's ecu.
you should see at least 23-24 mpg out of a stock neo in proper trim.