Td5 Erratic Tickover

[NomadABC]

Had the Td5 for two months now. Up to the last week it has ticked over reliably at just under 750RPM. More recently, it has become a little more erratic, with the tickover getting as high as about 800RPM and then dropping back eventually to what it was before. None of these variations are linked to engine temp.

Is this normal and am I fretting unecessarily, or do I have an excuse to fiddle?

[Jon v8]

I like a good fiddle ! trouble is it usually wakes the wife up !
Erratic idle is probably nothing more than oil in the injector loom,but some garages just change the loom in the head and clean out the ecu plug then send it out.Trouble is that sometimes you need to change the whole engine loom as well to get it right,and it doesnt always show up straight away.Get the oil in the loom out of the way before we start talking about other sensors etc.Good luck .

[NomadABC]

Thanks Jon. It just occurred to me that this problem might have started after I pressure washed the engine. Which connectors should I check first?

[edit] I assume the injector multi-plug is the one fitted under the left-front of the rocker box. If so, It had some oil in it, which I think I've cleared with a little acetone. I will have to leave the ECU multi-plugs 'til the weekend as this requires removing the negative battery lead. Is the Disco 2 the same as the 300Tdi in respect of all the faffing you had to do to disconnect the battery without the alarm going off?

[Jon v8]

Sounds like you are on the right track, dont worry about disconnecting the battery,just make sure you turn the ignition off fully for at least 30 secs before you unplug the multiplugs from the engine ecu.
In practice ecu's are a lot more robust than people think,so dont worry - just pull the plugs and look for the oil.Wash it out then try running it,hopefully it will be ok.

[NomadABC]

Will unplug the ECU multi-plugs over the next couple of days. From the outside, they look clean and dry.

Removing the mythology, what are the benefits/pitfalls of blanking off the EGR circuit? The diagnostics on the Rave CD always mention it at some point. Including those parts that deal with erratic idling.

[NomadABC]

Kept an eye on things today and a pattern has emerged, which makes me think this is not about dirty connections.

I drive the vehicle, then come to a stop. The RPM is about 800. After a couple of seconds it drops to about 780, then two seconds later it drops to 760, then to 740, which is the usual tickover. Occasionally, I pull up and the RPM starts at 740 then quickly jumps to 800 and then down to 780 after a couple of secs and so on.

Maybe there is a ghost in the ECU. What's this about?