is this normal on the s-afc?

[derK]

i'll do a simple rundown of my mods that matter.....
-lexus AFM (no adjustable screw)
-580 cc injectors
-AFPR
-walbro
-PLX wideband
-J tube removed
-K&N
-2.5" hardpipes
-FMIC
-blitz BOV
-Apexi S-afc

so anyway i *think* i have my base pressure at 20-25 PSI with the line ON. I have my throttle setting to 69% low, 70 % high (i think). I haven't really touched anything for my low throttle settings, maybe +2% up to 3000 RPM.

For my high throttle, i have +2% until 3000 RPM, and then i have to suddenly take out -8% of fuel from 3500 RPM till 5000 RPM. Why the sudden drastic drop??? my AFRs aren't steady but i'm not hitting the 12.0s for sure. If anything i'm jumping from 10s to 11s, to RICH, which is below 10s.

I'm afraid of dropping my fuel pressure even more because i think that it is low already. Plus i get a steady stoich reading at idle and at a normal driving pace. What can i do to keep my S-AFC as close to zero change as possible?? are atleast a consistent graph. I don't like that sudden drastic change from adding fuel, and then DROPPING fuel.

 

[AJ'S 88NA]

Maybe you can post in the piggyback section, Doc J knows everything about these.

 

[MDCmotorsports]

First, always set your FP with the LINE OFF.

Second, this could be a voltage switch issue with the fuel pump. Im not 100% on that.

From my past experience, you shouldn't have to put any fuel in with the 550/lex combo. You should only have to take fuel out up top....

 

[dbsupra90]

like jon said, adjust and reference with the vac line off the afpr. if you dont like to take the line off and on, just jumper +B and Fp in the diag box without the car running.

why do you have to add +2?

it would be easier if you mapped out your approx a/f per rpm, then your corrections.

example:

2000 rpm +2% 12.5:1
3000 rpm -4% 11.8:1