Disco 2 Rough idling TD5

Hi everybody,

I've tried to read every post that has a related issue to mine but still haven't fount my answer.
My problem is the following:

My 04 Disco2 TD5 is rough idling especially with the engine cold! (235k kms, if more info on the disco required just ask please )
It started end september after a offroading weekend in France all of a sudden on the way home and caused the whole car to shake at idle and accelerating, even at higher speeds. First thing i did when i came home is check the red plug for oil and i found 1 or 2 small drops in there, cleaned it out en changed the injector wiring loom to a new OEM one. Problem still there so i bought a very expensive but worth it nanocom .
There are no fault codes logged exept for: 2.8 ambient pressure circuit and 4.3 coolant temp circuit.
Also read a big unbalance between the cylinders: when cold 1. + 20 / 2. +15 / 3. -15 / 4. +- 2 / 5. -20 (average values) when engine warm: 1. +14 / 2. +5 / 3. -5 / 4 -4 / 5. -13 .
This is after i changed injector seals and washers! Before it was a bit worse at cold since i didn't dare to get the engine hot cause it was shaking much harder.
I reasembled the injectors as the rave manual says and i think i adjusted them accordingly..
What i've also did is replace the fuel filter (with a Mahle one) and the fuel air bleed valve.

Another problem i'm experiencing is the kangarooing when acceleration around 2800rpm, it doenst occur with the MAF unplugged (MAF was replaced very recently when i experienced power loss due to fautly MAF ) Yesterdag i noticed that the AAP readings are around 98-99 .. When i unplug the AAP sensor it gives more go and no more kangarooing either ... don't know if any of the thing have something to do with each other.

If anyone has some ideas please help me out! The disco is nog my daily but i prefer driving it over anything cause its freaking awesome!!

Thanks people!

Others more expert than me will come on and tell you more.
But it looks as if you need to replace your AAP and your MAF for a better one. These cars are very sensitive to rubbish MAFs even if you pay reasonable money for them they can be bad.
Basic question, after the wet, did you check out the air filter, its box and the drain plug at the bottom of it?
Best of luck.
(Allez les Belges! Ou etes-vous flamand?!)

Hi. If it runs better with AAP/T sensor unplugged you need a new one cos on Eu3 it has a temperature output too which is not covered by diagnostics but it's used by the management for fuelling calculations, if the MAF sensor was any other than the frigging expensive genuine LR better drive with it unplugged... do you still have EGR on the vehicle ?

as about the coolant temp circuit fault, what temp readings you see with nanocom when the engine is cold and hot ?

undo the oil filler cap and let it there at idle... is it slowly turning ?

Stanleysteamer said:

Others more expert than me will come on and tell you more.
But it looks as if you need to replace your AAP and your MAF for a better one. These cars are very sensitive to rubbish MAFs even if you pay reasonable money for them they can be bad.
Basic question, after the wet, did you check out the air filter, its box and the drain plug at the bottom of it?
Best of luck.
(Allez les Belges! Ou etes-vous flamand?!)

Click to expand...

Hi thanks for the reply!
The plan is to change the AAP indeed, the MAF was changed recently to this one https://www.jgs4x4.co.uk/defender-discovery-2-td5-maf-air-flow-mass-sensor-siemens-vdo-oem/
Air filter was still bone dry, changed to a pipercross one as well this weekend to be sure its good.

(Oh et je suis flamand )

sierrafery said:

Hi. If it runs better with AAP/T sensor unplugged you need a new one cos on Eu3 it has a temperature output too which is not covered by diagnostics but it's used by the management for fuelling calculations, if the MAF sensor was any other than the frigging expensive genuine LR better drive with it unplugged... do you still have EGR on the vehicle ?

as about the coolant temp circuit fault, what temp readings you see with nanocom when the engine is cold and hot ?

undo the oil filler cap and let it there at idle... is it slowly turning ?

Click to expand...

Hi Thanks for you reply! (i've read many helpfull things from you on the forum allready .

I'll order a new AAP sensor this week, what is the best to go? They are not cheap and the only one i can find really is a Britpart one (wich i heard are not the best parts).
The MAF is changed with this https://www.jgs4x4.co.uk/defender-discovery-2-td5-maf-air-flow-mass-sensor-siemens-vdo-oem/ (wich i found pretty expensive ).

I always tried to use the best parts possible, changed the injectore washers and seals with genuine ones as well.

There is no EGR on the disco.7

As for temp, i remember temps up to 93°C cause the NANOCOM gave an alert but then a bit later it was lower.. so think that is indeed at fault there.

Oil filter cap, do you mean the centrifuge filter cap?

Do you think any of these have to do with the rough idling?

Thank you very much for the help!

Hi. Unfortunately you wasted money on that MAF sensor, the ONLY reliable for Eu3 engines is with LR suffix, like this https://www.firstfour.co.uk/product/mass-air-flow-meter-for-td5-genuine-lr/ the same is valid for the injector loom too, "OEM" means nothing these days, just a marketing scam.
To rule out one thing for the rough idle use a good brand injector cleaner first, like this https://www.dealsforyou.uk/stp-high...leaner-fuel-system-treatment-200ml-1749-p.asp
The AAP/T sensor is also very important so i'd go for genuine too, when it comes to Eu3 engine management sensors the only 100% reliabe options are genuine LR , if you find it too expensive get a genuine Rover MHK100820 or genuine Delphi PS10133

I meant to undo the oil FILLER cap on the engine and watch it at idle, it should behave like in the video, if it doesnt replace the depression control valve LLN100140L (if you know it's old better replace it anyway)

I forgot to ask the catalyst is still on ?

Hey,

Oke, no funds at the moment to replace the loom and MAF with genuine. The air flow reading is pretty decent i think, its 628 at 1.14 bar boost and 3900rpm.

I allready have some 'forte' injector cleaner stuff in the tank, was told that that is also good stuff.. havent been able to empty the tank since i dont wanna drive it to much with the issue (but maybe i should just empty this, refill with the product you recommend and see what that does..)
I'll see if i can find a genuine AAP sensor (haven't been able to).

Oke mis read the FILLER . Ill see what it does.

Thanks!

here's a good AAP/T https://rimmerbros.com/Item--i-MHK100820

Laurensvh said:

The air flow reading is pretty decent i think, its 628 at 1.14 bar boost and 3900rpm.

Click to expand...

Those values are not OK, at 3900rpm and 628 kg/hr sucction under load you should get at least 1.35 bar boost, so better drive with that MAF sensor unplugged untill you replace the AAP sensor, with AAP unplugged the default is not so good like with MAF unplugged cos the boost is limited

sierrafery said:

I forgot to ask the catalyst is still on ?

Click to expand...

Hey,

No, decat with straight midpipe.

sierrafery said:

Those values are not OK, at 3900rpm and 628 kg/hr sucction under load you should get at least 1.35 bar boost, so better drive with that MAF sensor unplugged untill you replace the AAP sensor, with AAP unplugged the default is not so good like with MAF unplugged cos the boost is limited

Click to expand...

Oh ok, I'll try to do another test run this evening and check the readings with the MAF unplugged en de AAP plugged in.
Ordering the AAP on the website you gave. thanks!

Also if you had oil in the red plug keep cleaning it once a week untill all the residual oil leaves the harness... though you might have the surprise to find oil again in short time with aftermarket loom.... when i first fitted a non genuine one it leaked in 3 months but the main problem with them is that the contacts on the solenoids are weak and this can mix up the balance

Yes there was a little and i've been cleaning it every time I do something on the car. Last weekend there was a very little shine in the plug so cleaned it out again.
The plug on the rocker cover is still very clean. I'll keep a close I on that one as well and will get myself a genuine loom to be sure as soon as I can .

Thanks for the advice!

Check that blow by thing cos if the DCV is stuck the backpressure of the gasses can mix up injector balance as well

sierrafery said:

Check that blow by thing cos if the DCV is stuck the backpressure of the gasses can mix up injector balance as well

Click to expand...

Wow oke, i don't really understand what you are talking about here xD .

Blow by thing and DCV?

I own this disco since April this year and have zero prior experience working on cars .

Thx

If the blow by is OK the oil filler cap should behave like in that video, if it's bouncing and you get smoke there it's not OK... i mentioned the depression control valve(DCV) in my first post but it was edited so read it again, if you google out the part number you'll realise where that piece is(near the MAF) and at idle it must be fully open so if it's stuck closed the crankase pressure is mixed up, it's a plastic bit exposed to hot gasses so i consider it a medium term service item

Oh ok, I understand now end know wich part you are talking about.

I'm gonna bite the bullet and order the AAP you proposed and a Genuine DCV. While at it i'll also get a new genuine water temp sensor and a genuine injector loom.
Just to eliminate any faulthy things in the OEM part.

Gonna hurt but its for the good cause i guess..

I'm gonna do a test drive after work with the MAF unplugged and the AAP plugged and see if the kangarooing happens then or not.

Oke, I just went for a drive and i unscrewed the oil fill cap when idling. It didn't move quite as in the video you showed.. Also came some 'smoke' out upon opening.. could be due to cold weather or that i drove for 2 or 3 kms before i opened it..

Also noticed that without the MAF the kangarooing is still happening and the turbo pressure and wastgate modulator % goes down and back up with the hopping..

I do have some more prehistory that might shed some light on the issues..

In September I did a trip to Italy where the disco performed magnificent even till high(ish) altitudes to 2600m on a mountain pass. after that when home i started noticing more black smoke, didn't really see an issue at the beginning cause i never payed real close attention to the amount of smoke (on the trip to Italy I allready had the new MAF on because i had powerloss due to a faulthy one). A bit later the kangarooing or hopping started and i noticed that without the MAF it didnt happen or when i just pushed through it it got past the hopping and it didn't occur anymore till restart. So I went on a offroad/wildcamping trip in France with some buddies and had a blast (drove a full weekend without MAF). When 100kms from home the shaking in the engine started when driving/accelerating and idling. Got home, cleaned red plug, found a ripped turbo hose at intake manifold (probably the cause of extra smoke in the exhaust), swapped injector harness with OEM one and so on.....

Don't know if any of this has something to do with the other but I hope I can find my answer here and get the disco back in shape cause i love driving it!

Thanks in advance!

You'll have to replace the sensors then record a live data(inputs fuelling) log with all plugged in to see if it's overboost or turbo overspeed protection...unless the symptom goes away with good sensors.