My butt dyno said there was somthing amiss...not real bad, but a little less power for sure. I started watching my boost guage and it seems to peak about 0-3 psi lower than normal and drop off to 3 to 4 psi lower than before. I have a stock turbo and un-flashed stock ECU. The only thing I can think of is that this started happening after I got a fill-up. Maybe the octane was not the 92 that the pump stated.

Will the stock maps reduce boost if I don't have premium in the tank? thanks

 

bump ???

 

sounds like you have a boost leak somewhere. check all your vacuum line connections and tighten your hose clamps. if that doesn't change anything then i would do a pressure test. good luck.

 

plus ONe

 

the ecu will back off the timing if it detects knock.could very well be bad fuel.and as previously suggested check all air lines and clamps.