Fuel Trim Question

[kxc36g]

I have been fine tuning my AFC since I received my Scanmaster. At first my fuel trims were 135 low, 82 mid, and 81 high. I added fuel to get the low trim close to 100, I took away some fuel in the low RPMs to get the mid trip around 100. Both of these values fluctuate a bit, but they stay close to perfect. I keep taking away fuel but I have not been able to get my high trims over 87. Ususally they are between 84-86, even after making changes on the AFC. I started at -12 correction and am now at -25 for high trim. The resulting difference was 6 trim points; much less of a change than the low and mid trims for less fuel change.

Why are my high trims stuck rich?
The 02 sensor is cycling pretty normally (actually, throughout the -12--30 range) and I have an adjustable FP regulator (CAS).

Any thoughts, or should I leave this as well enough?

Thanks,
Chris

 

[R3dR]

what do you have your throttle points set at?

If you are never running in the high table the afc is not going to help you correct the high point.

I personally have mine set at lo 34 high 36

 

[DevilSperm]

have you tried resetting the ecu to zero it out and see where it goes from there? if not, that might make it easier

 

[kxc36g]

Well, these fuel trims are weird as hell. After running around for 3 days with out changing my settings, and having my high trim at the mid 80s, last night my high trim shot up to 95. I guess I just have a retarded high trim....

Next time I will reset the ecu, that would make tuning the trims easier.

In reply to the 'high' throttle point on the AFC, I am sorry but you do not know what you are talking about and I don't want misinformation spread. The high point on the AFC is not for the high fuel trim. It is for hauling ass. The high fuel trim is based upon air flow, and is the cruising RPM table. My AFC high fuel map looks nothing like my lo throttle map... about 30% different in fact. Even by your misguided logic, you do not cruise around town at 36% throttle. Go check out a tuning website, or someone like RRE, to actually learn how your AFC works. Best of luck with that....

Chris

 

[CanadianTSi]

Agree'd, your throttle points should be more like 20-80 or something like that.