OK, we are smashing our heads in on this one.

2004 Defender, 15p Engine Cylinder head has been replaced at some point with a 2006 dated head.

Car came in with a cam lobe badly worn (on injector cam lobe) Fixed that (replaced cam and injector cam follower/tappet assy).

Found debris in sump, so we checked the bottom end - found damage, so fitted new crank, mains, big ends, oil pump and seals.
Didn't remove pistons, but bores and crowns are mint, piston slop in bore is minimal.

Engine starts on the button and idles beautifully even from stone cold, cylinder balances nice - less than 5. No smoke on start and idle at all.

All's good right? Err no.

Apply a little throttle to raise the revs to about 1500 rpm, and a cylinder or two drop out, and billows white smoke that smells of diesel, cylinder balances go bezerk on cylinders 2 and 3. This is no load.

Here's what it's not (either fitted a new part or a known good part, pretty much in this order):-

• Injector Harness (This was looking dirty in the sockets so we changed it while we had the lot out - ECU harness is clean as a whistle)
• Injectors (Changed them out for a known good set with new LR seals)
• Fuel filter ( we fitted new filter and air bleed and one way valve - all were faulty)
• Fuel pump and Pressure regulator (Fuel pressure is bang on at 4.2 bar - rising to 5 bar when engine running)
• Crank Sensor (Tried a known good one - also scoped the signal)
• DMF (Checked it when we had the engine out - worn but good)
• ECU (Tried a known good one - albeit from a disco - also to check that it wasn't the tune)
• Cylinder head (Put a known good one on - we were thinking crack in the head)
• Since we changed the head, it's not likely it's a pumped up hydraulic lifter.
• Cylinder head gasket and dowels (see above!)
• Turbo (We are running it without the I/C at the moment while we are trying to figure this out, and it does it with the turbo not connected to the intake, so it's not oil from the turbo or an EGR problem)
• EGR has been deleted anyway.

No codes.
Scoped out the Crank signal - it's OK - no noise.
Throttle pedal signal looks OK - linear and contiguous action.
We are now chasing possible electrical gremlins - harness damage?

The harnesses that run alongside the gearbox have been crunched a bit by some previous work, so we pulled the engine harness out (Red plug from ECU into the engine bay) and found no obvious trauma, and all the engine harness wires buzz out ok.

Next step is to check the harness behind the dash into the engine bay...
But this really is scraping the barrel...

Starting to lose my sanity - I cant think of what it could possibly be that would cause this weird misfire, but give an absolutely "perfect" idle (that we haven't already checked).

Any ideas?

TIA...

Mike.

Hi, first of all i'd double check the timing chain to be 100% well set

I’ve had this, my timing was out a touch.

Cam timing? TBH, we discounted that it when we changed the cam. We always set it carefully with the crank and cam locking tools when we take a head off. Will double check.

I had the same thing after I rebuilt my TD5, I had had the injectors rebuilt and they were probably ok.
BUT after it initially started and ran really well, it started white smoking and miss firing.
After a lot of thought, ill try to find the thread on here, I removed the injectors and sent them to Merlin Diesels.
Turned out that one was FUBAR.
Im pretty sure it was caused by me, I think I didn't clean the head properly and some machining swarf got into the injector.
So Id suggest pulling the leads of each injector in turn to find the one that's causing the smoke.
Then get that one checked.

Edit to my post above
Pulling off the plug to each injector probably won't help, if an injector is faulty it may be "stuck" open, so its always leaking fuel into the cylinder, hence the white smoke.