our engine light keeps coming on stating cylinder three miss-firing

even after two head jobs and every single sensor replaced as well as gas cap

even gas tank and electrical work by qualified Land Rover repair shop but not

dealer... this has been going on for months.... light only comes during very

hard acceleration... we are now at a loss....

 

It's a Rover, sometimes these things have no explanation.

 

Have you replaced the plugs and wires?
Have they done a block test to check for cracks?

 

possible cylinder slipping. best way to tell is to add coolant dye and drive it awhile. Then pull the plug causing the misfire, if its the color of the dye then its a dropped sleeve. seen it a few times. the four middle cylinders are always suspect of that issue when its intermittent and the best thing to do is always replace individual things to make sure it goes away instead all the plugs and wires and coil.

 

when do you notice the misfire mostly? cold ? hot? under load? ive seen a couple times the lifter has taken a crap and valves hardley open. possible injector failure as well.

 

under hard acceleration.... injector was changed as was all cables and plugs....

 

normal engine operating temp....

 

pull out the spark plug and make sure its gaped properly