Jalenie

Hello, I'm seeking some information on what could be causing my A8L to misfire. Originally about 1 & 1/2 months ago my check engine light came on for "system too lean (Bank1) I took my MAF sensor out and cleaned it with MAF cleaner. I cleared the message and didn't worry because it still drove perfect. Then about 2 weeks ago you could feel the misfire only once letting off the brake after being stopped. Then my check engine light came on along with my EPC light and misfired very rough. I scanned it and it said misfire in cylinder 3. I then swapped coils with cyl 1 to see if it was spark plugs or coils. After clearing the light and swapping it said cyl 3 misfire still. I replaced my spark plugs and it still misfires slightly. Any suggestions to what it could be?

Jack88

A misfire can also be caused by an injector issue, sensor issue, or even a fuel delivery issue. I'd swap the fuel filter out for a new unit and maybe swap the injectors between the two cylinders. Not sure how difficult that is on that motor.

MP4.2+6.0

To diagnose well, a real VCDS scan is in order. Not code reader stuff to be clear.

Jalenie

I have used techron fuel cleaner and it did not change anything. So I thought I would try using sea foam but it didn't help. So then I cleaned the mass air flow sensor with the correct cleaner. Still nothing. Then I replaced the air filter. Still nothing. So after trouble shooting all of this I decided to order a brand new mass air flow sensor that should be here tomorrow (5/30/2017). It was only $50 on eBay. If this does not fix it I will go with your advice with a new fuel filter and then swapping the injectors. I would have done that by now but I have not been able to find information to help guide me through the process.

Thank you very much for the advice Jack

dvs_dave

How much time and money in random parts are you going to throw at it before you decide to spend the $199 needed on the tool that you actually need to find out what's wrong with it? aka VCDS

https://store.ross-tech.com/shop/vchv2_ent/

03_AR_CO

+1 on the above, and a factory repair manual should be in order as well.

Audi A8, A8L, S8: 2004, 2005, 2006, 2007, 2008, 2009 Repair Manual on DVD-ROM - Bentley Publishers - Repair Manuals and Automotive Books

KoJackee

I know it has been a while since you originally posted but could you provide us with an update or the outcome to your issue?