misfire and boost cut
 

I recently got my S4, i knew it was going to need some TLC...but it happen pretty fast. At idle it occasionally has a misfire. The scanner said misfire on cylinder 1. There might be other stuff, but thats all i remember at the moment.

the car doesnt seem to misfire above 2500rpms, but i could be wrong. Soon as the boost starts to hit the car has severe hesitation/misfire the check engine light blinks. Basically if i stay out of the boost it seems fine. Feels like boost cut though. Do you guys think this could be simple as a plug/coil? My gut thinks EGT sensor. maybe? what does limp mode do in these cars? cut all boost/timing?dealer is going to check it out tonight.

RE: misfire and boost cut
 

well i know this when your check engine light is blinking it is not good at all..and to the point that you should not drive it....have it checked a.s.a.p and bring your checkbook with you...haha:D

RE: misfire and boost cut
 

read the codes. If it's a EGGT sensor, it will throw a code.

Chances are you have a bad coil, or you need new plugs. I would change the plugs, & move the bad coil around to see if it pops up on that cylinder.

Use Vag-com to see the misfires.

RE: misfire and boost cut
 

I also have a phantom misfire at idle, cyl 5, but never flags a MIL. Run your car and spray the coils down with water. They occasionally crack, if this is the case, it will arc and youll see a spark jump. Also like 2K said, move the coil to see if the misfire moves. The MIL flashes to indicate the misfire is catalyst damaging, i.e. you are spilling raw fuel into the converters, no spark. Try that to start.

RE: misfire and boost cut
 

Thanks for the replys guys. I dont have a vagcom yet. buying one very soon. Ill keep you posted on the findings.

RE: misfire and boost cut
 

Replaced coil and spark plug on cylinder one. runs awesome now. :-) incase anyone was curious.

RE: misfire and boost cut
 

For the future, also look out for Vacuum leaks. I had an A4 come in with just one vacuum hose that was torn apart that ran under the coolant tank. This one vacuum hose that caused missfires on cylinders 1,2, and 3. and also set 8 other faults. fixing this one hose, cleared all the faults. But yes for missfires, coils and sparks are first. Congrats on the fixed car. have fun with that. :)