Evening chaps,

usual boring cossie missfire help needed here

Basically over winter i fitted an unskimmed low mileage 4x4 head, along with a new crank sensor. and since then its had a missfire high up in the revs even when not under load sat reving in neutral.

i thought maybe the new crank sensor didnt like my alloy pulley so i fitted a standard pulley, but still no better.

To summarise what we have tried so far..

Dizzy rotor and cap
HT leads
New plugs on standard gap
Phase sensor gap
crank sensor gap
tried a brand new loom
tried different ignition amp

We tried a different ecu and chip with the old loom but need to try it with the new. its all thats left to try really!

group a coil was fitted only couple years ago.

The cylinder head wasnt rebuilt before fitting and has started weeping oil out the exhaust manifold gasket after a couple thousand miles. as well as smoking when i pull away in traffic, so defo needs whipping off now for valve stems and guides (its not turbo). i wonder if a dodgy valve could cause the high rev missfire?
Sometimes i can get a good few full boosts on road before the missfire starts, other times it happens first time I boost when not even up to normal temp.

I understand its a boring topic that comes up weekly here lol, but any pointers would be much appreciated..

Cheers.