Hi All,
Looking for some help with an issue that's suddenly developed on my '00 Discovery 2 TD5.
The issue is that the engine stalls when revved. It's fine at idle, at around 2500 rpm, it starts to run rough (misfiring), then when pushed to about 2800, it stalls (rather revs drop to around 300, for a moment, until you reduce throttle, then cuts out entirely).
There are no codes logged in the ECU however as it cuts out, the Engine management light comes up (? Limp mode) and sometimes the water in fuel light comes on (not always).

Prior to this fault appearing, the vehicle was running as well as a 24 year old disco does.
Immediately prior, I adjusted the steering backlash, and replaced the serpentine belt (which was starting to frey) whilst the fan was off. The fault started immediately after this.

During faultfinding, I have replaced the crank position sensor (which has been showing a code for a while, and has now gone). I have also replaced the fuel filter, and fuel pump (which was 'hunting' originally, and now isn't)
I have also tested the wastegate valve, which holds a vacuum, and bypassed the actuator, to no effect.
I have also cleaned the injector harness socket (the harness itself replaced about a year ago), ECU sockets, and replaced the battery (swapped from another Disco which is working) to rule out those options.

I'm now at my wits end on this one, and hoping someone may have some ideas of what else to check. What I'm struggling with is that the work I did immediately prior shouldn't have caused this to suddenly start.

The car is a daily driver, used occasionally off road (normal laning, and nothing recent sadly), and occasionally as a towcar (again, noting particularly recent). I haven't modified the engine (though a previous owner has dome an EGR delete), so is pretty standard in case any of that is relevant.

Any help would be greatly appreciated.

Cheers
Olli.

Very similar symptoms on mine turned out to be a collapsed inner wall on the pipe between the turbo and the intercooler.
The rubber can feel solid/hard on the outside but gets delaminated inside and block the airflow as the revs increase.
Would start & tickover ok but with anything more than low revs, it would bog down as described, often but not always with loads of exhaust smoke.
Not saying it's that, but it's easy enough to check with a bit of dismantling.
Maybe also do a bit of searching on here, as there have been similar previous posts, I can't remember what the answers were, but usually involves having a nanocom as a starting point...

I was about to suggest looking at the turbo wastegate actuator but the delaminating sounds more likely.

Hi both,
Thanks for the suggestion, it's something I haven't looked at so I'll get the spanners out tomorrow on my day off and report back. Sounds possible and at this stage I'll try anything!
Cheers,
Olli.

check oil level, also could be fuel pump

So after checking all of the intercooler hoses from the turbo to the inlet manifold, I have found them to be in good condition with no signs of delamination.
MJI - oil level is within range, and the fuel pump is a brand new unit fitted when this saga started.

Now back to looking for suggestions I suppose?

As it only happened after the work you mentioned, I am inclined to thinking that maybe it has something to do with the serpentine belt.
Did you replace the tensioner at the same time?
Have you tested the alternator?

So the alternator appears to be working no issues.
I'd agree it must be something I've done, but cannot see what that would be. I did not change the tensioner at the time I replaced the belt as it seemed to be functional. The belt was only replaced due to spalling on the belt itself (something I noticed whilst I was in there and thought I'd change whilst the fan was off).

Do you have a diagnostic like Foxwell or Nanocom?
Maybe live data might be the only way of finding the problem.

Also have a really good look around everything you might possibly have touched when doing the work you did.
Either side of the engine there are SOOO many things that can rub against one another.
Thankfully there are the little access plates on the inner wings behind the wheels. So I used these to get in there and isolate anything that could come to harm with split garden hose and cable ties.
So you could do worse than examine anything that could be leaking current to earth or another wire.
Do you know what caused the spalling to the belt?
Best of luck with this, feel for you.

Have you tried unplugging the MAF and running it like that? If there is a fault there it'll run fine without it connected.
Also check the fusebox under the bonnet which is very prone to problems.
Maybe @sierrafery has some suggestions?

So I've tried with my normal code reader which does show limited live data, with nothing abnormal showing. I'm waiting on a neighbour who has a slightly more advanced reader to see if that shows anything more.
I visually inspected what I could, and can't see anything abnormal, albeit with all the oil and general muck in the bay it's hard to be certain. I will clean up the area I was working in and see if anything comes to light when cleaned.

The reason for mentioning oil was injector washer leaks.

Later TD5s run bad with no maf, so if no change.

Being a '00 model it should have a 10p engine and thus disconnecting the maf should present no problem.
Mine is a '00 and runs fine like that.

Yes it's a 10P engine. We did a run without the MAF connected, and no change.
Today, just because I could to rule anything out I swapped over the turbo to one I happened to have spare with no change.
It seems to have enough oil, and hasn't been drinking any more than usual, but is there a way I can check injector washer leaks without removing the injectors?
As an aside, I was thinking about running it very briefly without the belt on to rule out anything with that being replaced being a cause. Have you done this and if so, how long is it ok to run like this? Thinking maybe 30 seconds max just to see if it stalls again.
Other option is to put the original back on to reverse that change and see what happens.

You say you changed the fuel pump, did you fit a genuine Valeo unit.