Just had my UrS4 MOT'ed... it failed its emissions at the main dealers 3 months ago.... now passed without any fettling
it was noted that the boost doesnt "feel" as urgent as it should be,its still a reasonably quick car but its not as fast as it should be..... being accustomed to the RS4's performance coming down 150 bhp or so WILL make the S4 "feel" slower
now I have had a quick chat with an Audi engine specialist and it sounds like without doing log runs or a vagcom check that the N75 boost control valve could be on its way out.
is this common on these engines? dread to say that mine could be the original fit
in which case 215k miles isnt bad going!!.
all hoses have been checked and are tight, no leaks, and the turbo spindal has been checked and thats fine to.just as well since its a fresh turbo in there!!!
where is the N75 on a 20v lump please and is it an easy swap?