Recently purchased a low-mileage S5 Turbo and am experiencing a "misfire" in the rpm range cited above. Below 2.5K or above 3K, or when accelerating, the problem is not apparent. It only shows up as kind of an intermittent stutter when holding the rpms steady in that rev range.

The car has had the emissions removed and it has an Apexi SAFC II with manual boost controller. The previous owner had it tuned and WHP is 218 at ~8-10 psi boost according to the dyno sheet he provided. Engine compression is good. R1 is 118-125 psi, R2 is 117-121 psi (see chart). I have no information on any porting that may have been done to the engine.

Installed new plugs and wires, checked timing, and will be pulling the fuel injectors soon to have them cleaned and tested. Any suggestions for what else to look for will be appreciated.

Thanks, Larry

 

Hi Larry

Im having the same issue with my s4 currently. Did you end up fixing it ?