Today we isolated the No 1 injector and coil pack. Started the engine and it smoked, but it soon started to thin out with hardly any smell of fuel which all looked very promising.
So I assumed it was a faulty injector, replaced with a new injector, started it up and straight back to smoke and smelling of fuel.

I also found today all the other plug are as back as the ace of spades. so it is running rich still.

have you now confirmed that although running rich/smokey , that the dodgy injector/plug is now firing, so running on all 8 cylinders? plug is black, but DRY? can you check that you don't have an air leak on the induction. when you changed the pcv, did the cyclone tube get checked/changed? is that blocked? (at rear of engine)

Sorry forgot to mention it's still misfiring and No 1 is still wet. all the others are black with soot.

All the PCV system was changed or cleaned where needed.

I need to check all the induction system as this problem started the same day I changing the air filter. approx one hour after.

mmmm, so you changed air filter, and then white smoke, or did you change PCV and white smoke or both together...like I said, you seem to have two faults. smoke, and misfire.... but I wonder if engine is shutting down cylinders, in an attempt to aleiviate smoke? with info from cats. you must have the engine light on, on the dash yes?

PCV & MAF was done after the problem started.

I have a flashing engine light

We had the diagnostics on it today and it only comes up with the misfires and faulty injector No4 BUT if we clear them and run it up again it flags up misfires in different cylinder numbers sometimes 2,4,5,7. we had cylinders 5 so I swapped the coil pack and plug with No 1 run the diagnostics and it through up No 5 again.

We are going to get it on the T4 testbook next week to try and get some live data.

So you disconnected the injector on 1 and basically it stopped smoking. I think that proves you had unburnt fuel being shoved out past the valves and causing the smoke. You assumed it was a faulty injector so replaced it and the problem came back... It sounds to me like it is not firing on 1 and is electrical, not an injector.
Is the compression still down on 1? Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

Yes that is exactly what we thought.
So we changed the injector, as the auto electrician had passed all the electrics fro the ECU down to the plugs.

But there is still not something making sense. Is the problem fuel, electrical, sensors????

We haven't done another comp test yet

Does the plug spark? Have you taken it out, held it against the block and actually seen a spark as it turns over?
Is the block properly earthed as well? Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

The electrician said there was a good spark on all 8 cylinders so I haven't conducted this test myself

I will go back to basics on Monday.

Check the induction system for leaks
strip out and test /clean every injector
Strip out and test every spark plug and coil pack.

re assemble and see what happens. before we plug in the T4 on Tuesday.

Anyone suggest anything else to do.

I would keep it concentrated on cylinder 1 to start with as that seems to be worst one... Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

Do the ECU's pack up on these?

as I mentioned earlier., you need to remove the coil pack (on suspect misfire cylinder), and fit ANOTHER spark plug to it, and leave it wired in, with a disconnected a plug in the affected bore., as engine will start when cranked! run a test lead from earth to the plug body the plug in the coil pack), or a good jump lead. observe if the coil pack and plug are sparking. try and do it in bad light, it makes it easier to see. lower bonnet down if sunny...its possible you have a spark signal pulse, but no earth return. ie the coil pack has two connections, pulse and earth. if you can prove a spark/no spark, you know where to think next. ie pub/kettle..

I had a similar problem on a p38 v8 and did a smoke test with a smoke machine and had a slight weep air leak on inlet manifold but also although no 2 was sparking it was sparking weak and at the wrong temp new plug and reseat of the inlet manifold job done but it was the smoke test that helped hope this helps

Thanks guys,

I will try this tomorrow