Misfire when warm

[David]

From your description of the location, and if the fluid is coolant, then your leak is possibly at the underside joint of the alloy crossover-over piece and the intake manifold at the thermostat end. Leaks do occur there (I have had one) and unfortunately are generally caused by "plastic rot" at the gasket between them. Hopefully not, since that requires a new intake if it is. If so, the coolant leak has most probably caused the spark plug hole to fill up with coolant and short out the plug. Remove that coil, one 7mm bolt, and take a look. Incidentally not all coils may feel 'rock-solid'. Not a problem since the bolt should not be over tight, Ford say only 6Nm. They can easily strip the intake brass thread if you do over tighten. Fitting coil packs with dielectric grease is always a good idea anyway, but clearly any coolant leak would need fixing for other reasons too.

David

[Roadrunner]

Best to remove and clean the windscreen washer jets from the bonnet and refit them using a bit of sealant as that is a common source of water ingress above the coil packs.

Another possibility for causing a misfire is the main engine harness plug at the back left side of the engine bay on the bulkhead (when standing at the front of the car). It's the connector with a bolt to retain it in place. Remove the bolt, unplug and check for slight corrosion and clean with a good deoxidising electrical spray like Servisol.

[Trower36]

Ok, thanks for all the replies, I’ll pull the offending plug lead off and see if we’ve coolant in there it would explain the misfire but I’ll also check the harness connection as well, hopefully I don’t need a new intake!