C63newdude

So I took the car for Service A with just under 9600 miles. For the last few days the car was running rough at iddle, you could feel a vibration /shaking inisde the cabin and thorugh the seats and getting into my body.

During the Service A the dealer proceded to change the K&N filters for a pair of stock filters because the technician read misfault codes stored on ECU. The car runs great and the vibration at iddle is now gone.

The filters were a little bit dirty. Coming from a background of tuning a lot of cars I found in the past that yes indeed a simple air filter can change the AFR dramatically so on my situation I did not want to argue and I am happy to roll back on stock air filters.

Anyone having issues with CEL once in a while using K&Ns? I must admit I am geographically in one of the worst spots in the world(Altitude, poor gas-91oct , extreme heat and moerate dust storms) and I strongly believe smalls things like these can affect the performance.

Sincity

What if you cleaned the K&Ns?

C63newdude

^^^ From what I am reading on the pink report it was too much air going through. Who knows, maybe cleaning them whould had fix it but now that the car runs good I rather not take the risk. I will be puting the K&N for sale soon.

gOt BoOsT

untuned cars run extremely rich so your a/f would not change enough to cause lean conditions with just air filters. rough idle relating to a/f is usually a sign of too much fuel not enough air

C63newdude

I took a gamble on it. I don't know how to reset the car ECU, maybe unpluging the battery terminals would fix it or cleaning the air filters also or maybe plugging a OBDII scanner(I think they don't work on the C63 though).

I believe what you said but I also believe the delaer pink report. Unfortunately I haven't put the car on a dyno to see the AFRs, I have an AEM wideband laying around on my garage and I might actually connect it. Ultimately I was also looking at buying that Ipod software/OBDII scanners that gives you multiple readings like MPG, volts, AFR, etc.

From a customer/owner point of view I must say that I am happy to just run the stock air filters for now, whatever they did(replacing the air filters and /or reflash it) fixed my iddle anoying vibration. Regardless,thanks for your inputs, I am hoping with my recent experience that I can help someone out by providing feedback

Sincity

Are the charcoals still in there?

bhamg

Where does this come from? I think it's the opposite...under closed-loop it's likely on the lean side...under WOT I saw 13:1, as high as 14:1.