Looking for some advice / technical help.
My R53 has started missfiring at hot temps / under load. Prob 3000rpm upwards.
Twice had service light come on and it go down to 3 cylinders. Codes were p0204 and p0300. As soon as you switch off, leave a min and restart its fine again.

I have swapped out, plugs, coil pack, ht leads, fuel filter. Also removed and ultrasonicaly cleaned the injectors.
Its driving me mad. Any suggestions

Cheers

 

P0204 is the cylinder # 4 injector circuit. Have you checked the injector wiring harness and the # 4 plug?

 

Changed out the plugs for a brand new set, I checked the wiring as best I could when I had the injectors out, all looked ok. Voltage check shows 8V going to each with ignition on. Mot sure how to chdck this shile running under load.