I own a 2001 XK8 vin SAJDA42C51NA15311 that developed an occasional miss fire on start up when having sat for 30 t0 40 minutes. If I rev the engine the miss fire will clear and the car will run fine. A code reading revealed #301,302,1216. As I've said this is a intermittent problem having happened 5 or 6 times over a couple of months.
Submitted by stevejag@sbcgl… on Wed, 02/19/2014 - 12:34
I can think of a couple of possibilities.
The first being a failed check valve on the in-tank fuel pump. That can allow fuel in the fuel rail to siphon back to the tank when the engine is off. Then on start up the takes a few seconds to properly pressurize the rail. The result is a momentary rough engine.
The second is an injector that leaks fuel when the engine is off. That can cause a 'flood' of fuel to a cylinder on start up, also causing a roughness until the excess fuel clears out.
Obviously it could be none of the above, but in any case will require some competent diagnosis.
Good luck!