I'm using a S-AFC to tune my AFRs as close as possible to 11-11.5 throughout my rpm range. My problem is this: When I tune in 2nd or 3rd gear and I achieve ~11.5 afrs, then I floor it in 4th and especially 5th, my ARFs read about ~13.00 which I really lean for ~12psi. Now, if I tune in 4th or 5th and achieve 11-11.5 AFRs, and then floor it in 2nd or 3rd, I get ~10.00 AFRs which is too rich. Any ideas why this is happening?

720cc secondary injectors
full 3" exhaust
ported wastegate
stock s5 turbo
stock top mount

 

what is your fuel pump, and what is your fuel pump voltage at WOT?

 

My fuel pump is a walbro 255. I rewired it so it has a constant 13-14v at any time including WOT.

I mean the AFRs seem to lean out as I go in a higher gear... because where the load is higher?

 

Yes, that is exactly the reason. What are you using for tuning?

Try tuning for 4th gear and see what happens.

 

What is exactly the reason, the load difference? I'm using an A'pexi S-AFC Neo for tuning. So, are you saying without a sand-alone you can not achieve a certain AFR in all gears?