I just wanted to let you guys know that after reading my letter, AoA flew two engineers from Michigan down yesterday to inspect my car. Actually, they are flying around and inspecting a number of owners who have evidenced power loss/build-up/CELs etc., so they can get some information together to better understand whether this an endemic problem for the RS4, or if its in isolated instances, etc. All of the feedback was relayed to me by the local Audi engineer once AoA had inspected the car. He did say that the corporate engineer would call me eventually to discuss further.
What the local engineer told me was that they “thoroughly” inspected the car without removing the intake manifold. Apparently they can scope the back of the valves by removing the spark plugs. They said that there was a “normal” amount of build-up present which they said is expected and the level of build-up did not warrant any action.
After their inspection on the intake manifold, and trying to figure out why I was claiming power loss, they said that the vacuum hoses in the rear of the car were not completely closed off when I put on the aftermarket exhaust and that was to blame. Apparently those hoses are part of the same vacuum pump that regulates intake flaps (and a couple of other flaps). Without those fully engaging, I was noticing a loss of power in the higher RPM range.
I know this is partially true (partially in that the hose was at least part of the blame for power loss) as I had only recently realized that the hoses were not capped off (thanks to ArthurPE giving me the heads up to check those), but only had time to duct tape it (versus something more permanent). When I “taped” the hoses, I did notice a change in the power delivery of the car (a nice improvement) immediately. This was done some days before the Audi inspection.
Audi said that even with the “tape” there was some vacuum leak. They removed the tape and placed a permanent cap and “noticed significant power gains.” I’m not sure that I could feel the different between my “tape” and their “cap” but at the same time I could no longer argue that they were not “right” as there was improvement in the power delivery of the car.
Basically, by plugging the vacuum leak created in the exhaust hoses, I notice significant power gain…but no longer have a “baseline” to compare the car to confirm that the extra carbon may also be reducing power (as far as I can tell…I have more power than I did before…but do I have the same power as day one…not sure??)
I guess for now I have to just be happy with her and hope that there are not long term issues ahead. As long as the carbon is at a sustained level and not growing, I’m happy with the car.
I’d be curious to hear from any of you that have had discussion with Audi…Also – check your vacuum hoses if you have aftermarket exhausts!!!!
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Originally Posted by two2
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