Hi Everyone,

Just wanted to see if anyone could steer me in the right direction when it comes to these codes.


P0308 - Cylinder 8 misfire

I was doing some spirited driving when all of a sudden the car goes into "restricted performance mode" and starts bucking and sputtering. At first, the car shows a misfire at cylinder 6 & 8. After resetting the codes, only cylinder 8 shows a misfire and the car is sputtering badly. Could it be ignition coil, injector, or spark plug?

P2135 - Throttle/Pedal Position Sensor

When I had the hood up trying to make sense of the misfire code, I heard the Throttle Body motor just buzzzing. I would unplug it and plug it back in and it was still buzzzing. Subsequently, this code pops up. Any thoughts?

Only background I can give about the problems is that earlier in the day I used the CRC Intake Valve Cleaner (which I have used several times without a problem) and also one of my Mina Intake Y-Pipe rubber hose fittings kept popping off at the airbox right before the the restricted performance mode. The Jags performance mods are a tune with pulley and the Mina Air Intake Y-Pipe.

Kind of baffled on the whole situation. Any advance would be appreciated.

 

Sorry - Forgot to mention that it is a 2012 Jag XFR - 5.0 SC

 

With both, I'd start by suspecting power (and thus #1 the battery).

If not that, probably best to make sure the hose is 100% vacuum tight and after that try swapping coils / put in the stock tune etc.

 

Great Feedback...I also forgot to mention that I switched to a small lightweight battery and I just returned from three week trip. So obviously the battery is not at full charge.

 

Update - I had the plugs changed and one coil pack replaced. The culprit was a collasped electrode of the spark plug on cylinder #8. My thoughts are that I revved the engine too hard when injecting the CRC valve cleaner. I remember a massive backfire at the time and was very concerned that I hurt the engine. The car is running really strong right now. My other plugs show some carbon build up but I think in part due to the CRC cleaning.

 

I also changed the battery to a new Interstate Megatron 2. I was using a small lightweight Odessey battery and it was causing so many little problems - ie; throttle position sensor.