KA MISSFIRE

[rigsby29]

i hope someone can help me out with this one, my wife has a 54 reg ka 1.3 duratec that has a missfire on tickover, i have fitted new plugs/leads & coil pack, i have pressure tested each cylinder & they have good pressure but i have discovered that if you relase the pressure from the header tank the missfire stops!! it does not use any water but when it is hot there is no water in the header tank until you release the pressur then it returns,,,this has got my head done in please help

[Zad]

I think I would be inclined to get the header tank tested for hydrocarbons. It does sound like there is a small crack or whatever in the gasket and it is pressurising the coolant. Even though it has been pressure tested it could still be leaking. I suppose the water pump could have failed, making the water boil and causing the ECU to stop the engine.

[rigsby29]

im getting that done on wed, im going to swap the heater pipes over now as they look like they may be on the wrong way(the engine was out to straighten the chassis when i bought it from a salvage yard)dont know if that would cause it but its worth a try