Disco 2 Td5 Misfiring at high revs

For the past month I've had an issue with my Td5 misfiring at high revs when in 3rd and 4th gear. Would the collective assume that this is an Injector Loom Harness problem and that oil has seeped into the ECU plug or has this happened to someone else and that isn't the cause and it's down to something else?

Any pointers in the right direction would be gratefully appreciated.

Is it standard? I.e not mapped or running higher boost?

I would tend to think that whenever a Td5 engine starts misbehaving oddly for no apparent reason the first place to look is the injector harness. Check the red plug on the engine ECU for oil contamination.
It doesn't hurt to look.

bankz5152 said:

Is it standard? I.e not mapped or running higher boost?

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Sorry, should have added this info. It's not remapped, had EGR delete over a year ago, MAP sensor cleaned and recently a new MAF sensor too. Haven't checked red plug but will do hopefully this evening.

adrianhartopp said:

Sorry, should have added this info. It's not remapped, had EGR delete over a year ago, MAP sensor cleaned and recently a new MAF sensor too. Haven't checked red plug but will do hopefully this evening.

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As @Brian4 said, that's your first port of call. I disconnect the battery neg lead before I do this.

New maf sensor, was it Genuine though? Unplug it and then see if it stops

Seems like overboost so my money is on the wastegate modulator.... if no change with MAF unplugged remove fuse F2 engine bay and if that cures it replace the modulator

Discodevon said:

New maf sensor, was it Genuine though? Unplug it and then see if it stops

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Had ordered a Lucas one but supplier had problems with Lucas parts so sent a Delphi one instead.

adrianhartopp said:

Had ordered a Lucas one but supplier had problems with Lucas parts so sent a Delphi one instead.

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those are both aftermarket ... better without them... the only acceptable aftermarket is Siemens/VDO which is not perfect either, the only 100% reliable one is Genuine LR(also made by VDO), though if the engine is 10P(Eu2) the MAF can't cause serious trouble, eventually a bit of smoke or consumption issues

Think I've found the culprit!!!

Just been for a ride out with MAF disconnected and all smooth on high end revs under acceleration. Pulled over and plugged it back in and it start missing again.

Am wondering now if the part I bought is still under warranty.

Thanks for all the advice though, really grateful for all the input.

Did notice too that my wastegate rod doesn't move at all. Should you be able to move it with your hands?

It'll take some shifting with a set of pliers, but it should move.

OK, will try that in the morning then.

Thanks.

Classic maf issues mate I been through that with my old D2 Siemens Vdo in the plain white box are alright but no where near as good as Genuine, in a Genuine Land Rover box... all other aftermarket are dog poo...

Genuine Land Rover MAF on order, should be here tomorrow, and faulty one being sent back to supplier as still under warranty.

Will update once new part is on, just in case anyone's interested.

Still can't shift my Waste Gate though, so that might be the next thing that needs some attention....................

Hi, Have a look at this YouTube video

Griff

It will be maf. Just make sure you haven’t been sent a vdo one in a white box, take the turbo arm off x2 10mm bolts

This evening I've replaced my MAF with a brand new, genuine, Land Rover MAF. Taken it for a good spin and it's not missed a beat, kangerooing at high revs is now gone (albeit £140 lighter). Here's hoping it lasts for a good while to come.

Thanks for all your help and input, wholly appreciated.

Now, on to the siezed waste gate actuator, then the rust on the nearside rear wheel arch, then the lack of rear mud flaps, then the leak around the back door, then something else too no doubt................!

Knew I'd spoken to bloody soon!!!!

Drove to work this morning and it's missing in high revs in 3rd and 4th. GRRRRRRR!!!

Got home and checked the red plug on the ECU and I think there's more oil in that than there is in the engine. Why the fcuk I didn't check it first is my own stupid fault!!!!!!!!!

So, an injector loom harness and rocker cover gasket will be on order in the morning and that will be the next job.

Still got to try and free up the frickin' waste gate too.

Latest update

Oil cleaned out of red plug to ECU, injector loom harness and rocker cover gasket changed.
Waste Gate control Valve changed.
MAF sensor changed for genuine Land Rover one.

Still missing in high revs in 3rd and 4th, also seems to have lost some power too.

What else can I check/change?

adrianhartopp said:

Latest update

Oil cleaned out of red plug to ECU, injector loom harness and rocker cover gasket changed.
Waste Gate control Valve changed.
MAF sensor changed for genuine Land Rover one.

Still missing in high revs in 3rd and 4th, also seems to have lost some power too.

What else can I check/change?

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I’m pretty much in the same boat here buddy, am ordering a diagnostic tool as I’m just guessing now and am no further forward.