Friends S4 with RS4 kit has issues!

Its been fine for years running 20psi, then last week it started cutting out under high boost. Currently it runs ok up to about 12psi boost then starts to cut out / hessitate. Recently we put in a cold air intake and a drive shaft stabilizer. Vag tool shows missfires at idle in several different cyclinders (not a lot andnot the same cylinder). Checked coil changed with another cylinder did the same with spark plug, no change. Mechanic replaced O2 sensor drivers side before cat. Cleaned Maf no change, changed and tightened hose clamps on intercooler tubes no change (have't done a pressure check). Did notice small amount ofold oil in intercooler tube on drivers side (blow through I guess).

Whats next, check actuators on turbos'? (pain in the butt). Check bosch 710N valves? (whats the best process). Could it be spark plug gap? Injectors? Mechanic saidthey wereflowing ok (I guess from Vag as he didn't remove them). Other O2 sensors? Could it be something to do with the stabilizer bar?

Appreciate your input.

 

Slapper.


with misfires and low boost it sounds like a boost leak some where. Do a pressure test that would be the next best step.

 

Do you have TCD?

My guess is your having throttle cut from the ECU.

VAST sells a TCD that will cure throttle cut.

Can you do any B115 logs? See what actual & requested boost is?