T5 cyl1 misfire has me stumped

[classicswede]

I'm having issues with a total misfire on cylinder 1, shutting the cylinder off makes no change to engine note regardless of fuel being used. It does come up with the code for cyl1 misfire and rear O2 sensor

What has been checked so far,

compression is between 160-170psi on all cylinders. Leak down test gives similar results on all cylinders,

plugs have been changed and swapped with no change,
coil packs have been swapped and aso a new one tried but still no change,
The plug can be seen to be sparking when tested with a plug on the coil with the engine running.

Cranking over with the injector rail pulled out shows all injectors to be firing evenly. Injecor pulse width is identical on all cylinders as it should be.

I'm stumped now and dont know what it could be. We have compression, fuel and spark yet the cylinder is totally dead

Any ideas?

[Harvey]

Any engine work done or was running ok then just started.?

[Harvey]

What does the plug look like when removed after running engine wet with fuel or dry ?
No damage to coil pack harness , good earth .to harness and engine earth.
you could move injector on the rail to see if it moves .
valve stuck shut ?
sounds a strange one .

[classicswede]

The plug is getting slightly wet but not as much as I would expect from a cylinder that is not firing at all.
I have moved the petrol injectors from cyl to cyl and the same with the LPG ones but no change. Also tried disconnecting LPG fully but no change either.

A valve stuck shut is something I had considered but hard to check - will need to remove the inlet to see what is going.

Wiring to the coil appears ok, I replaced the signal wire as the sheathing had split but no change with that either

[M-R-P]

May be a pin on the ecu?

[Soulboy]

Was just gonna say the same through bitter experience-if it is that then I have a remapped replacement sitting right here (-;

[classicswede]

ECU is a possible and something I have considered. If it had been a P1 I would have dropped in another ECU to confirm.