just woundering if anyone has an idea on what could be doing it. at about 4000rpms amd 0.6 bars of boost is when it happens on my s4. if anyone has an idea let me know.

 

What are you asking exactly? Is there a pinging noise or knock?

 

Oh sorry wrong thread, If your car is an 02 or newer it may be the immobilizer thats messing with you, do you see a light in the instrument cluster like a car with a key through it? Or if there is a yellow light flashing when the engine shuts off?