On my Audi I just bought the car knowing it needed a new transmission. I bought it and fixed the transmission. It had a check engine light before i fixed the transmission P0302. Then I found out it needed a new battery. So i replaced that. And I still get P0302 which I know is Cylinder 2 misfire. Could the battery have caused this? Other than plugs/wires what else can it be?

The P0302 is solid...Its not blinking.

Also, not sure if this is related,when i turn left the wheel feels tight and it feels like it is grinding on something.

The brakes and rotors and tires are all pretty new.

Any ideas on either of these two issues?

 

The grinding is most likely a wheel bearing... Common... Most German tuner/service shops will do it for less than $150.

As for the SAE P0302 / VAG 16686 code, the battery would not have caused this. Start by checking your spark plugs. Check the gap on #2 and the overall condition. Clear the code and see if the problem continues. Bentley states that it could be an injector problem. It is always good to do some fuel system treatment. Use BG 44K..... (picture below) It is the only thing that works in my opinion. A little costly, but so effective that it is kept behind the counter at the parts stores here in Colorado. It smoothed out the idle on my car, and helped the gas mileage. I highly recommend. This is a first and comparatively cheap solution to taking the car to someone for an injector analysis.

If neither of these simple things changes the situation, it is time to diagnose the coil packs. Invest in a Bentley manual, it will tell you how to check the coil packs for proper operation.