I have a 2008 q7 with the 3.6. 60000 miles. Was having problems with rough acceleration after the car had been sitting. Check engine light would come on. Audi cleaned the carbon build-up and power difference is huge. However, the rough acceleration has returned after a couple of weeks. No check engine light yet. It feels like it is misfiring with gentle acceleration. It does not do it or it is less noticeable with heavy acceleration. Anybody have the same problem after the de-carbon process?

On another note, the valve clatter on cold starts seems to have worsened with the carbon cleaning.

Thanks in advance

 

What did Audi charge for cleaning the carbon build-up?

We took our 2008 Q7 to the dealer for the cold-start rough acceleration and check engine light and they won't do ANY diagnosis until they FIRST replace the spark plugs AND clean carbon build-up? For that, they want over $600. We only have 60k miles. Do the spark plugs really need to be replaced at 60k miles?

 

Yes I had the same problems and replaced the Knock Sensor which helped.