TD5 Defender - missing when hot?

You said it had to cool down and was playing when hot. Any idea how hot as the TD5 should have a limp mode to stop you really cooking it. Maybe that is the problem. The smoke could just be the unburnt fuel finaly being spat out.

Unfortunately just because something is a known issue to us doesn't mean that the mechanics will pick up on it (sad, I know :( ).

I will see if I can find the thread that someone posted about how to check for oil in the ECU, I'm sure there were pictures in there - just hope they didn't get blown away with the site move.

I'll see the bloke on Friday so hopefully I may be able to squiz into his battery box and have a look at his ECU...

EDIT: No idea how hot, his temp gauge (like most of ours) just runs up to the middle of the mark and stays there. Though as I said he'd been driving it for a good 45mins in traffic (going up to 80kph at times too) before the engine warning light came on

Grizzly,
It almost cetainly sounds like oil in the wiring harness. This issue has been discussed several times on the forum and it is not essential to replace both the injector harness and the engine harness. If it is not this then it is going to be something more serious, like an injector or head/head gasket.
You can remove the injector harness and seal it as a precaution and maybe replace the o rings. There should be some previous post on thi subject when I did mine. The harness connector is a poor design as is the harness in general. As the connector to the main engine harness is a cup type the oil can pool in it and then transfer allong the harness wiring to the ECU connector where it will cause interference with the firing pattern for the injectors. The easisest way to check is to pull off the connector harness at the front of the head and check for oil ingress. I have put a new one in mine, but kept the old one and gave it a good clean and sealed it up at every point where oil may be able to seep along the wiring and into the connector. I am looking at wether a drain hole could be drilled into the connector. Once the oil gets into the main engine wiring harness it takes a bit to get it out and some say you have to replace the engine harness which can be expensive and time consuming. This is not the case, the harness needs to be flooded from the connector with copious amounts of wd40 or non plastic deforming contact cleaner (ordinary contact cleaner can melt plastic), through to the ECU connector. You will need to keep disconnecting the ECU connector fro several days and mop up residual oil/wd40 until clear. The oil will not get into the ECU as it is sealed at the connector.
I replaced the injector harness and did the engine harness clean, spraying in contact cleaner and wd40 over a 10hr period every 1/2 hr with the ecu plug disconnected and laying in a plastic cup to catch the flow through.
I paid about $130 for my new injector harness, but have the second one (original) as a back up should it happen again (fully decontaminated of oil).
Cheers
Craig

Are you sure it is not just a worn or faulty cable from the battery. I had a similar mysterious problem with my 02MY Defender which started as a very rare/intermittent electrical cutout and got steadliy worse. The service centre eventually found it was a faulty main power supply cable from the battery under the floor to the ECU box under the drivers seat.

Everybody here was doom-saying about oil in the harness, but it was just a plain old dodgy wire. Just happened to be the main wire that supplied power to everything (including the hazard lights). Because it was that simple, and upstream from the engine management system, no fault was logged.

The deterioration was understandable just due to jiggling around. When things got really bad I even got the car started by shaking it from side to side a bit - it was that touchy.

Another prognosis for my problem was a dead short circuit. Several places where this could have occurred, but again only a few where it could kill the entire car. Worth checking the main earth cables in any case - he could have hooked the one from the battery box to the transfer case off-road at some point.