Car basics:
S4 N/A, S5 rotating assy, largeish streetport, T2 rotor housings
Corksport headers, HKS cat-back, generic OEM cat.
Ported TB, brake duct CAI
Electric air pump actuating the aux ports, factory N327 ECU

The previous incarnation of this engine had everything minus the T2 rotor housings and the headers, and pulled great up to 7500. Since the recent rebuild however, there is a mild stuttering up above about 5500. Afraid I was going lean up top, I installed a wideband system, but if anything I'm running too rich. The AFR gauge drops into the 10's up that high. Not optimal for power, but it seems that the turbos run that without significant problems.

So what do the gurus think might be the weak link here? Are AFRs in the 10's too rich for an N/A? Factory ignition just can't keep up?

Thanks
Andy

 

Turbo is an entire other animal. 10's are way too rich for NA. Do you have a fuel computer at all?

 

Nope, factory N327. Been thinking about an RTEK. That would fix a few things and give me some more control. I've seen that a lot of people use the S-AFC, but I'm not a big fan of trying to 'trick' the ECU.

Thoughts?

Thanks
Andy

 

Bogging the engine or possibly blowing the spark out. It could even be way lower than 10.0 because many gauges don't read lower than that. Didn't think the stock fuel system though could put that much fuel in the motor. I really don't know much about stock systems.

 

Yeah, after all the horror stories of modified engines going lean, I was rather surprised to see it running so rich.

 

Sounds to me like spark is being blown out.

B

 

Na's will get more power going leaner to a safe point.