So i have a 2003 Audi A4 - 1.8 - about 90k miles. I bought it at 84K miles, No check engine light, car ran great but did an occasional hiccup.

Recently i felt it starting to ride rough and the check engine light came on. Took it to Autozone and got it scanned. i got the p301 engine misfire code. So to eliminate the coil, i swapped coils on cylinder 1 and 2. it drove decent for about 25 miles, then the check engine light came back on and the engine strted driving rough again. went back to Auto zone and got the same code p301.

So i had my plugs changed- all 4 plugs...the engine light turned off and the car ran smooth for bout 50 miles. The check engine light would blink ocassionally but always goes off. the next morning the light came and stayed on, engine rode rough again... Same code p301..

What else can be the problem... I can still drive it. the roughness doesnt start until you reach about 40mph .. i can still drive it regardless to 70mph highway speed. i notice my gas mileage is bad also...

What seems to be my problem? i tested to prove it wasnt the coils. i replaced all 4 plugs.

 

These are a few I pulled from other sites with that same CEL code.

- Clogged or faulty fuel injector 1
- Fuel injector 1 harness is open or shorted
- Fuel injector 1 circuit poor electrical connection
- Ignition coil 1 harness is open or shorted
- Ignition coil 1 circuit poor electrical connection
- Insufficient cylinder 1 compression
- Incorrect fuel pressure
- Intake air leak

Maybe check your injector and the connection to the coil to start.