Disco 2 TD5 Smoky - but a nice old bird!

Well I am confused, I have recently purchased a Discovery 2 commercial (51 plate 15P engine) apart from requiring a new clutch I had the smoky cold start issue which I put down to two possibilities:-

MAF sensor or Injector seals, I also noted it was VERY smoky when idling for a long time and smoked like a Trooper (excuse the pun!) when pulling away. It never smoked on over run or whilst driving. It goes like a train and is not down on performance - the most poky TD5 I have owned (I already have another one overseas in Africa).


I have changed the following:-

• Injector seals
• MAF sensor
• Turbo bearing and seals
• Given it an Italian service got KMH and MPH mixed up on the motorway and thought I was doing the speed limit to clear intercooler of oil.

Cold start is a little better but I do not think seals had been breached, it was evident that the seal had been changed on injector 1 only at some time. But smoking it still does! No apparent loss of oil... but no real miles yet.

Any way funny thing is it flew through its MOT yesterday - I was genuinely shocked especially as I was smoking all the way down the road after 10 minutes of idling in the MOT station but the emission readings are well below spec. cylinder balance from Nanocom is a bit hit and miss on cylinder 1 especially in the 1100-1600 RPM range anything up to +28 (not under load though when its fine).

There seems to be mixed feelings around TD5 injectors some say they are bullet proof others bemoan them. I have ordered a second hand spare but wanted the forum thoughts for me and others?

Give us all your views?

if the injector is at +28 its way out of range and is probably the reason for it smoking, the other 4 injectors try to compensate for the faulty one, i changed mine a short while back for a guaranteed second hand set it solved the smoking and rough idle, one of mine was +11, the remainder were around +3 to-3 approx

Run a can of injector cleaner through the fuel tank. It cant make things any worse and just may clean things up.

Thanks for the feedback..

Cleaner put through and a good run up to Birmingham and back with 400KG on board returned 31MPG over 230 miles @ 70-75MPH and a fair amount of A-B roads - incredible for 1990's technology!

Ordered a second hand injector just in case... I love the TD5 no matter what the 200/300 Tdi purist's say. A bit of TLC and careful maintenance these engines will go on forever - easy as long as you have a Nanocom - lets be fair!

Will see how it goes on the smoke front..

Well I changed the injector on cylinder 1 for a second hand unit and swapped the injector from cylinder 2 into cylinder 1 to ensure that I had not purchased a duff unit.

All injector seals have been changed, but on cold/warm start it is very lumpy and the balance issue on number 1 cylinder is still showing up to +30 on the Nanocom when raising the RPM above idle to 2500 RPM. At idle it is fine but leaves a trail of smoke up the road when pulling away from cold.

When the engine is up to temperature the issue disappears and the disco goes well and is not down on performance. MAF is good ECT/IAT temperatures match, no apparent combustion gases when removing the oil cap so I am still confused.

As per my original post went through the MOT without issue. So the question is should I leave the problem or pursue the issue just in case I am damaging a piston/cylinder bore?

Anyone else experienced this before could it possibly be the injector wiring loom (no oil at ECU or at the cylinder head plug).

Thoughts?

1. did you set the injector codes with nanocom after the swap?

2. if you have nanocom read some live data on the sensors, black smoke means overfuelling which could have more reasons, i attach you the good readings(see page 2) ... injector balance is relevant usually at idle

3. are you sure it's not remapped?, or some tuning box attached? ...cos if it is and it's not the best job it could give you smoke and bad injector balance without any management "hardware" fault

Thanks for the reply..

Yes I did set the codes via Nanocom, MAF readings are spot on as are all other readings. It is only on free fast idle that it is lumpy and belches blue/grey smoke with high imbalance on cylinder 1 only (when not up to operating temp). No smoke black or otherwise under load or engine braking. My other TD5 Disco is perfect and does not have this problem (unfortunately its in South Africa so I cannot change all the injectors).

I must admit a remap has crossed my mind as being a potential cause as it goes well compared to my other Disco. I think the previous owner tried to get it fixed as there are signs that Injector 1 had been replaced. The only other possibility is the temp sensor on the AAP which the Nanocom unfortunately does not read (goes into pin 31 on the ECU).

Just bl**dy annoying really and would like to get to the bottom of the problem to ensure I am not heading for an expensive holed piston/bore wear from a freeloading injector - excuse the pun.

replace the wastegate modulator and check it's pipework, it's not expensive, worth a try cos there are 2 elements matching:

In the event of a turbocharger wastegate modulator failure any of the following symptoms may be observed:
l Reduced engine performance.
l Increased engine performance.
l Lack of power.
l Excess smoke.
l Reduced fuel economy.

Click to expand...

search PMK100130 it's around 20 quid

Before you go any further with this,consider an electronic compression test with a current clamp around the battery lead whilst cranking the engine.I have seen these symptoms many times with TD5s and 90% of the time they are down on compression on one or more cylinders - usually a bent rods...
The last one I did was my own DII,which smoked when cold,had an injector imblance on cyl 1 but cleaned up and ran well when warm.Turned out the con rod on cyl one was 17 thou shorter than the others.(Plus worn big ends/mains etc) That the engine ran so well when warm was down to clever electronics compensating for low compression on that cyl,also showing that balancing data on TD5s can be misleading as it didnt show any difference to the other cyls when warm.
The engine had history,the head was a year newer than the car,all the exhaust valve guides were worn out as was the cam and rockers.Obviously nailed back together by a bodger...
Not saying this is what is wrong with your engine,but the compression test is quick,cheap and easy - no spannering glow plugs/injectors etc.And the results will steer your in the right direction.If it is down on compression you can decide if its worth taking it apart,just remember they are not a cheap engine to repair,mine cost me well over £1000+Vat in parts and I only did shells,rings,gaskets,oil pump,one rod,timing chain and guides etc.Crank was fine along with a hone of bores etc.So no pistons,rebores or crank grinding etc.
You can also forget replacing the boost modulator,they will happily run direct off boost pressure like Defender engines...

What about wiring as I have heard that that can go faulty

eightinavee said:

You can also forget replacing the boost modulator,they will happily run direct off boost pressure like Defender engines...

Click to expand...

did you actually try that? ...i'm asking cos on mine the modulator was stuck open and there was plenty of black smoke and the consumption increased with at least 25%... IMO is not healthy to let a D2 without overboost protection, it has different management than the Defender... but i'm not a specialist though

sierrafery said:

did you actually try that? ...i'm asking cos on mine the modulator was stuck open and there was plenty of black smoke and the consumption increased with at least 25%... IMO is not healthy to let a D2 without overboost protection, it has different management than the Defender... but i'm not a specialist though

Click to expand...

Yes, one of my customers had one running with a pipe direct from the intercooler hose to the boost capsule on the turbo.It ran like that for several years till he scrapped it about 6 months ago,that car will be made in to a pickup in the near future,cant imagine anyone is going to change it back...
The boost solenoid was left in place and still connected electrically,just no pipes attached.On live data from T4 it behaved in the same way,still holding boost down to about 230KPA under full load,performance felt exactly the same.I guess the LR egnineers were looking for more refinement etc when developing the TD5 for Discovery so went the electronic control route.But when an owner is on a shooting trip in Scotland with a failed solenoid and constant overboosting, it gets fixed on the side of the road in any way possible....

interesting... i presume that in my case the management "saw" that the modulator is stuck and used some default values which gave me that black smoke and increased consumtion... which makes me think that you need a well working modulator even if it's bypassed, so why not use it then?... but i'll remember this bypass thing as a good temporary fix...thanks for the answer

sierrafery said:

interesting... i presume that in my case the management "saw" that the modulator is stuck and used some default values which gave me that black smoke and increased consumtion... which makes me think that you need a well working modulator even if it's bypassed, so why not use it then?... but i'll remember this bypass thing as a good temporary fix...thanks for the answer

Click to expand...

The black smoke was because of overfuelling before the ecu cuts it because of overboost,the smoke was also your increased fuel consumption.The engine ecu will happily accept the boost control from the direct connection from the intercooler pipe to the boost capsule on the turbo.
If the solenoid failed on mine I wouldnt bother replacing it....

i agree with that ... but doesnt the permannent open valve act like a bypass? ... cos after the modulator was replaced everything went back to normal

Cant remember,is the normal state for the solenoid closed ? (Was about 3/4 years ago I did the mod...)
If it were open and failed in its open state as you say it would act just as it would with a bypass,if not my customers must have stuck shut...

i blew through it and nothing happened when i gave it 12V supply....the ECU monitors it's status as you can see on diagnostics live data and if the ECU gets a bad signal from the modulator it will act accordingly... bypass it and unplug the solenoid on a well working engine for test...if it will not produce smoke and the mpg will stay the same it means mine had a problem with the MAP or MAF too then and i'm wrong...,but if a well working engine engine will behave different with the good solenoid bypassed and unplugged IMO it's not a healthy thing to do... cos i think that's the reason for bypass, that the modulator is faulty and to not spend money on a new one...cos if you must keep a well working modulator there for the management then IMO that bypass is worthless

i've looked into this a bit deeper... i'll cut the story as short as i can cos i know you'll understand what i mean: the gist is that the ECM controlls the wastegate modulator through a PWM signal on the earth path... that's why you can see on live data the % of wastegate... the ECM based on the fuel map and the addaptive strategy uses this signal together with all the involved sensor's signals to manage the engine's operation... so if you bypass the wastegate modulator the wastegate will not act as the ECM expects it based on the PWM output which has a specific fueling strategy for each position and things are getting mixed up then... as long as the modulator is still plugged and working


if the modulator is unplugged and the modulator bypassed the ECM gets open circuit information and enters in a default mode in which the D2 will act exactly as a Defender...without running issues etc....just take into account that the D2 Td5 due to it's management has 11Kw more power than a Defender from factory even if the engine is the same. Think about that


here is from web-rover page:

In Defender specification, the Td5 develops 122 bhp (120 PS, 90 kW) at 4200 rpm, and in the Discovery this is upped to 136 bhp (134 PS, 101 kW) at 4200 rpm by use of a different fuelling map and an electronic wastegate.

Click to expand...

eightinavee said:

Before you go any further with this,consider an electronic compression test with a current clamp around the battery lead whilst cranking the engine.I have seen these symptoms many times with TD5s and 90% of the time they are down on compression on one or more cylinders - usually a bent rods...
The last one I did was my own DII,which smoked when cold,had an injector imblance on cyl 1 but cleaned up and ran well when warm.Turned out the con rod on cyl one was 17 thou shorter than the others.(Plus worn big ends/mains etc) That the engine ran so well when warm was down to clever electronics compensating for low compression on that cyl,also showing that balancing data on TD5s can be misleading as it didnt show any difference to the other cyls when warm.
The engine had history,the head was a year newer than the car,all the exhaust valve guides were worn out as was the cam and rockers.Obviously nailed back together by a bodger...
Not saying this is what is wrong with your engine,but the compression test is quick,cheap and easy - no spannering glow plugs/injectors etc.And the results will steer your in the right direction.If it is down on compression you can decide if its worth taking it apart,just remember they are not a cheap engine to repair,mine cost me well over £1000+Vat in parts and I only did shells,rings,gaskets,oil pump,one rod,timing chain and guides etc.Crank was fine along with a hone of bores etc.So no pistons,rebores or crank grinding etc.
You can also forget replacing the boost modulator,they will happily run direct off boost pressure like Defender engines...

Click to expand...

Thanks for the response, I will follow through with the electronic compression test, I have a clamp just need an oscilloscope. I have now gone through the whole electrical system using RAVE this is to check the readings that a Nanocom cannot pick up (AAP air temp.).

- Injector wiring check - resistance back to the ECU connector - all good
- AAP temp reading - resistance matched the IAT within 200 ohms (around 16 degrees)

This appears to be a fairly common problem but none of the threads/posts on any forum appears to have resolved the issue. I raise it again as after using the Disco in the garden this weekend pulling out shrubs in low ratio with the engine running for no more than 10 minutes from cold the disco smoked like a trooper when I drove it through the village, almost like a piston ring had gone - very embarrassing. If I drive away when the engine is under load the smoke is minimal. I think a compression test is the last port of call before the head comes off.

I have previously replaced a conrod on my daughters Rover L series when she hydraulically locked it when going through a flood. The difference is that the engine ran lumpy (3 cylinders) until warm, it was obvious what the problem was so I am not so sure this is the cause but have run out of options. The imbalance on cylinder 1 is only on fast idle and not at idle or when hot.

Anyway I am hoping that this is not the problem (bent conrod) if anyone else has an alternative option before head off it would be appreciated.

eightinavee said:

Before you go any further with this,consider an electronic compression test with a current clamp around the battery lead whilst cranking the engine.I have seen these symptoms many times with TD5s and 90% of the time they are down on compression on one or more cylinders - usually a bent rods...
The last one I did was my own DII,which smoked when cold,had an injector imblance on cyl 1 but cleaned up and ran well when warm.Turned out the con rod on cyl one was 17 thou shorter than the others.(Plus worn big ends/mains etc) That the engine ran so well when warm was down to clever electronics compensating for low compression on that cyl,also showing that balancing data on TD5s can be misleading as it didnt show any difference to the other cyls when warm.
The engine had history,the head was a year newer than the car,all the exhaust valve guides were worn out as was the cam and rockers.Obviously nailed back together by a bodger...
Not saying this is what is wrong with your engine,but the compression test is quick,cheap and easy - no spannering glow plugs/injectors etc.And the results will steer your in the right direction.If it is down on compression you can decide if its worth taking it apart,just remember they are not a cheap engine to repair,mine cost me well over £1000+Vat in parts and I only did shells,rings,gaskets,oil pump,one rod,timing chain and guides etc.Crank was fine along with a hone of bores etc.So no pistons,rebores or crank grinding etc.
You can also forget replacing the boost modulator,they will happily run direct off boost pressure like Defender engines...

Click to expand...

Well I got down to stripping the old girl down yesterday as the (new) clutch thrust bearing seized solid and left my future son in law, stranded so box out for the second time in a year (the "part" company who for the moment will remain nameless as I may seek recompense - have now gone for Valeo a lesson well learned!).

Anyway Eightinavee had it spot on, 2 bent conrods on cylinder 1&2 cylinder 1 was bent over a millimetre and cylinder 2 by 0.2mm. Luckily took a punt last week `and bought five conrods and pistons off fleabay for £40 delivered. Also found that the camshaft timing was out by at least 10 degrees (marked pulley and timing casing before removal of the head) will clock in with a dial indicator and re-mark prior to assembly as per RAVE manual!

I have a theory that bent conrods are caused during the injector seal replacement as research seems to show that its always on cylinder 1. I always crank the engine to blow any residual diesel out prior to re-fitting injectors, if this is not carried out I believe that cylinder 1 (logically the one that is removed first and floods) hydraulically locks on cranking and bends the rod.

It appears that both cylinder 1 & 2 are glazed so I will deglaze these prior to fitting replacement pistons rods and new rings and big end bearings (against the advice of RAVE!). Interestingly the ring gap was still within spec (0.3mm) after 146k miles and hone marks still clearly visable on all other bores.

Finally as I saved money on the rods I will de-cat and replace the mid box with a straight through pipe, also have my own mild home grown remap (EGT limited and personally tested to 750 degrees with Madman- avoids warped manifold) which are on my other two Disco's in South Africa (BTW I can also de-brick ECU's for a pint or two for those who screw up the Nanocom map loading process- the ECU is not double buffered so if it fails so will your ECU - beware!).

Anyway thanks for all those who contributed will send a post once the old girl is booming with the new exhaust!