I have a 1999 S4 and the vehicle will boost and perform well then it goes flat with no boost and when i plug vag com in i get the code
17965 charge pressure control. Positive deviation
P1557 35-10 intermittent
So far i have checked all the VAC lines and have replace the rubber Y pipe to the throttle body as that was split and used the revised clips that was 3 days ago and i was hoping that was going to be the fault but clearly there is another problem somewhere.
The car its self drives faultlessly it does not smoke its runs very smooth and has good power delivery until i get that fault it does not put up a MIL light it just drives flat. It has a full Audi history and has been maintained
My next step today is to pressure test the boost circuit to see if i can find any other leaks.
The car also ocationally stumbles as you back of throttle i was thinking this could be down to warn re-circ valves.
So im thinking of replacing
Both re-circ Valves
Im fairly new to audi ownership so im still learning about them i am a qualified mechanic and am finding this quite frustrating not being able to pinpoint it
If you have any suggestions i would apreciate it. i will also report back later if i have any findings from the pressure test
Thanks for you time in advance