heres my problem my S5 TII rebuild was running fine for the past 1500 miles but yesterday It started to loose power at around 2200 rpms,its started to knock when i shifted to third and i lost almost all the power.I did a small test run today
and the car drives fine on first and second gear but the moment that i shifted into third i lost all my power again this is driving at normal speed not shifting past 3500 rpm but iff i go on 3 gear above 3800 rpms theres a diference its stop knocking but it does not pull that hard and the turbo its not spooling up the way it used to be,my car use to have a nice low end pull thanks to my NA rotors but its gone i feel like 25 percent off my horsepower its gone and i dont know what the **** happen.i did a compressino test and its fine i test my injectors and there working fine timing its fine and im going to check my tps tomorrow,did you guys have any ideas please help me out.
Heres my setup its on a S4 NA chassis
S5 TII WITH S4 NA ROTORS
STREETPORTED
S5 TURBO AND MANI
550 PRIMARY 720 SECONDARIES
THIRD GEN UIM AND PORTED TB
RB TURBO BACK(3)
WALBRO FUEL PUMP
HKS FPR
N333 ECU WITH MATCHING PRESSURE SENSOR
AND FLOW METER

 

compression test? i hate to say it but you might have a dying motor. i'd check that first

 

If it ran fine and it just started doing it, I'd rule out things that might have been missed during the engine re & re. 2200 RPM sounds eerily familiar - I remember an old TII that I had where the wastegate actuator rod came off because I had lost the little clip that holds it in place. It later drove me nuts because I'd put it back on thinking I'd get to it later and couldn't find the time. The car did exactly what you're describing. If you can't find anything obvious, checking the TPS may be a good place to start - make sure each pot gives you smooth continuous resistance readings. I've seen S5 TPSs do weird things without even spitting out codes. Don't forget obvious things like things that might have come off or a clogged cat. I'm also assuming that the check engine light did not come on, or you would have checked codes if that were the case.

 

Lift the fuel pump assembly out of the tank and check that the connecting hose on the pump has not split.
If it's OK see if the fuel rail damper still has a small phillips head screw fitted in centre of diapram. If there is no screw or hole don't worry, it's a later version.
(the damper is the one without a vac line)

 

my questions is why it only happens at 2200 rpms and then stops when you reach around 2800 maybe 3grand,why only happens in third gear,some why sometimes its so bad that i need to downshift,and why it doesnt happens if ishift into third above 3grand

 

my questions is why it only happens at 2200 rpms and then stops when you reach around 2800 maybe 3grand,why only happens in third gear, why sometimes its so bad that i need to downshift,and why it doesnt happens if ishift into third above 3grand

 

Um, you're using S4 rotors in your S5 engine?
Did you change out the counterweights / flywheel too???


-Ted

 

yes i did ted