Cold or hot start up no issue: Consistent above 3000rpm misfire throw p303, every time all the time. Can drive up 3000 rpm without any issues, but once past... it throws code p303 and the misfire is felt.
Replaced ecu (other issues), cps, coil rail and plugs. I also replaced the o-rings on injectors 3 and 4 as well swapped them. When I replaced the leaky valve cover gasket. I saw no coolant on the top of the head by cylinder 3 ( of course could be crack still).
History: XJ's PCM was damaged due to reversed polarity jump start. Bought one online...
-Is there a chance the PCM used could be bad and cause this?
-What's next on the list to check?
-331head?
-compression?
-injector wiring?
Thank you all.
Replaced ecu (other issues), cps, coil rail and plugs. I also replaced the o-rings on injectors 3 and 4 as well swapped them. When I replaced the leaky valve cover gasket. I saw no coolant on the top of the head by cylinder 3 ( of course could be crack still).
History: XJ's PCM was damaged due to reversed polarity jump start. Bought one online...
-Is there a chance the PCM used could be bad and cause this?
-What's next on the list to check?
-331head?
-compression?
-injector wiring?
Thank you all.