D2 Td5 Engine Revs Surging/Hunting 75-125rpm

I have had a 2001 Disco2 Td5 since June 2014, and ever since I completely flushed all oils and de-EGR, the rev-counter shows the vehicle hunting when between 95-105kph.

I can even feel the engine slightly hunting/surging. It's not a major, its just annoying. But get this, don't be rude, it doesn't do it when in cruise control!

Before anyone blames me - I swear, its not! None-the-less confusing...

OK... had a go today & confirm that it does it in both cruise & driver control. Seems to be something with the torque-converter lockup, which comes in at 85kph. Still annoying though...

is the injector loom ok?, i mean no oil in the red plug nor in the upper one?

Bit of oil in the (upper?) black plug going to the loom in the head. Clean it out, & now no probs. Thanks.

then replace the injector loom ASAP before the oil gets to the red plug too

WhaaaaT? Reeally...? What is the issue here? Can I not seal it up some way?

Why are you so surprised?...the web is full of this issue... sealing it up will not be the cure cos the contacts within the plugs to the injector solenoids are already weakened, that's the main issue not the oil cos as you improved contacts in the plug by cleaning the oil you can't do that with the plugs on the solenoids too cos they are submerged in oil all the time... the new genuine injector looms are better made lately to override this issue... it's not so expensive to bodge it with sealant there to risk worst issues IMO

Okay, thanks. I agree with your arg. Anyways, just replaced my coolant hose and removed the ECU to check red plug. Totally dry... I notice that the loom runs down from the black plug to a low point, then back up to the red plug. So I think the issue of oil at the red plug is somewhat mitigated. Still, thanks for your help. Will order a new loom... :tea:

Anyway, after buying a new harness and cam cover seal, I removed the old harness to see that the o-rings around the fitting that sits in the head were flattened off. Off to the local garage for two 24mmIDx3mm o-rings, and after using CRC Electrical Contact Cleaner of the plugs (both on the old harness and the injectors) I replaced the o-rings and re-fitted it. It solved the issue of "chugging" when lifting off on the accelerator at low revs.

Interested to know what buggared my camshaft cover seal, however.

so you didnt fit a new harness only replaced the orings... this ''cure'' will not last long no worries