So my 20001 A6 2.7T just started running really shady at idle and at times will still. At higher speeds, after about 2000 rpm and accelerating, I get a vibrating / rattling noise from what sounds like the drivers side. this prooblem came out of no where and was running great before. I am thinking cats but dont want to do that then find it to be O2sensor or MAF. any help will be greatly appreciated.

 

P0300 is "Random Multiple Misfires"

P1128/P1130 are "Fuel Trim Too Lean" bank1/bank2

Try cleaning the MAF first and leaks around/in the intake system. its the easiest thing to deal with. I think if your O2 sensors were going you would get more/different codes.

 

Thanks for the advice..... I tried to clean the MAF and i checked the intake system for leaks with NEG results. I did notice quite a bit of oil in the Y-pipe, looks like it coming from the PCV valve. currently trying to find someone local with a VAGCOM. Any other ideas?

 

Also, I recently noticed if i am easy on the throttle and brake, it will idle fine at a stop. but once you want to get up and go or need to stop quickly it will start to run rough. still hearing a rattling on heavy exceleration. And found it to be very intermiate, could run rough at one stop light and great at the next. Figure if I cant figure it out this weekend i will just have to suck it up and take it to a shop. Thanks for the help.

 

Check for any tear in intake piping? Sounds like a an air leak from a hose or a connector to me.

 

Any ideas where to start? before or after MAf or Turbo or Intercooler?

 

check all the "soft" hoses first. the throttle body boot is one that is very susceptible to getting tears in it. it is one of those things that you have to inspect very closely. the tears are small and relatively imperceptible.

 

UPDATE

Toke the car today to a local import shop. They found both bypass valves had blown diaphrams and want to replace the MAF. They also stated that the MAF readings were OK at idle but swung outside of limits under load and at cruise. NOW, my problem is noticed mostly at idle when they say the MAF is in spec. Could the bypass valves be what is messing up the MAF? And does the bad bypass valves sound like this could be the little gremlin i have been chasing? They also pulled individual misfire codes from each cylinder. Thanks again....

 

Today I recieved my 2 new 710N bypass valves from supremepower.com. I installed with no change in preformance. car is still shakey with a rough idle. I unpluged the MAF thinking it would go into a safe mode but still no change.

 

So i replaced the spark plugs and tested the coils. Noticed the all the plugs came out red ( looked it up, from additive fond in octane booster?) I went ahead and did the plugs, fuel filter, and am now running a bottle of lucas fuel injector cleaner. Today, I felt like i was getting more pick up with it and the RPMs dont bounce as much at idle but still have a hiccup ( large RPM Drop) from 3rd to 2nd and 2nd to 1st. also at idle, even though the RPMs are a little smoother, at times it does seem rough, louder and jerky at a light. Every shop says something else and nothing seems to actually solve my problem. Thanks