2003 TD6 engine vibration and overfueling cyl 5

I have owned and maintained my 2003 L322 TD6 for 12 years now and have been able to figure out and solve most issues by looking at solutions to problems reported by others. This time though I am at a loss and would appreciate help and advice from the experts on this forum.

Vibration started suddenly when parking the car after a normal 30 minute drive. Suspected an injector gone bad and a quick check with my Foxwell diagnostic tool revealed massive over fueling on idle on cylinder 5. Replaced the suspect injector twice with spares I had available knowing from experience these tend to go bad after around 100K. However this time the vibration symptoms and over fueling reading remained identical with both one new and one refurbished injector.

There is also white smoke on idle. All symptoms seems to disappear at revs over 1700 rpm.

Also checked the injector wiring loom with a meter, all ok, no breaks or shorts.

Any thoughts and advice highly appreciated.

Some injectors need to be coded to the car - are the Td6 ones of those type?

I have replaced all 6 injectors previously with success. No coding needed.

Any issues with coolant loss?
Is there any excess moisture from the exhaust even after a warm up?

So the ECU is detecting overfuel via resistance from the solenoid on the injector thinking its jammed open?
So if the same reading and symptoms remain could it be an ECU connection?
Corrosion on a harness plug at the ECU?
If you varified the hardware then maybe the problem is towards the software end?
Have you checked continuity from the ECU plug to injector plug?
Are these injectors earthed to activate or positive fed to activate?

Pull the connector from the dodgy injector and see what you get.

Diesel injector loom is known to go bad in bmw's.
AFAIK the loom is about £60.

Mark Piercy said:

Any issues with coolant loss?
Is there any excess moisture from the exhaust even after a warm up?

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Sorry for late reply. Have been working on the car all day. I do have a little coolant leak near the fluid reservoir so its hard to say if there is any leaks else where. Smoke is slightly greyish, not white as I think water vapour would be. Hard to say though its winter here in Norway and all cars smokes a bit at 10 below.

Mark Piercy said:

So the ECU is detecting overfuel via resistance from the solenoid on the injector thinking its jammed open?
So if the same reading and symptoms remain could it be an ECU connection?
Corrosion on a harness plug at the ECU?
If you varified the hardware then maybe the problem is towards the software end?
Have you checked continuity from the ECU plug to injector plug?
Are these injectors earthed to activate or positive fed to activate?

Click to expand...

I have opened the E-Box and removed the whole harness to inspect and test indoors. Checked all wires for connectivity, all seems fine. Cleaned all connectors (looked fine under a magnifying glass) with oxide cleaner and flushed with electronics cleaner.

Injectors are earthed to activate.

Datatek said:

Pull the connector from the dodgy injector and see what you get.

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Sorry for late reply, have been working on the car all day. When I pull the connector on the dodgy injector the smoke clears after a little while. I guess the residual fuel needs to get through. Car then runs ok, less responsive of course and a bit of vibration at idle.

tanis8472 said:

Diesel injector loom is known to go bad in bmw's.
AFAIK the loom is about £60.

Click to expand...

I checked continuity on all wires in the harness and all seems fine. Also the ECM does monitor the wiring I believe and should throw error messages if there was a problem with the wiring. My diagnostic tool reports no errors from the engine, only overfueling in fuel compensation live data for cylinder no5; -5 to -7 mm3 at idle. In addition there is a marked vibration at idle.

Could of course still be the harness so I will get a new one, where can I get one for £60 ?

Are these injectors plumbed into the head like the Audi 2.0tdi?
There is network of fuel lines inside the heads. Does this engine have the same or are the fuel return and supply lines out side of the head?

I have

Mark Piercy said:

Are these injevinje plumbed into the head like the Audi 2.0tdi?
There is network of fuel lines inside the heads. Does this engine have the same or are the fuel return and supply lines out side of the head?

Click to expand...

Both supply and return lines is outside the head. It is the BMW M57 30D engine, BMW owned Landrover when this car was designed.

Could an ECM hardware failure affect only one cylinder ? I guess it could happen but then again the ECM seems will protected inside the E-box. Guess I will have to find someone to help me scope the output signals to the injector to see if there is anything weird going on.

I have been thinking all kinds of doomsday scenarios today; cracked head, blown head gasket, ... but I can not see how this would cause an injector to overfuel ?

https://blackbox-solutions.com/help/SM073.html
I wondered if there is anything you pick up from here. Interesting reading.

Mark Piercy said:

https://blackbox-solutions.com/help/SM073.html
I wondered if there is anything you pick up from here. Interesting reading.

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Thanks, indeed interesting reading. The description under DDE4 TD6 - FUELLING COMPENSATION makes me wonder if the ECM is "overfuelling" to compensate for a mechanical problem with the sylinder; "Important information on Fuelling Compensation: This display shows the fuelling adjustments to individual cylinders. The cylinder balancing function adjusts fuelling to each cylinder so that each cylinder is at running at the same speed. The variations in mm of fuel to each cylinder are shown. With the engine idling the fuelling adjustments should mirror the variation in cylinder speeds shown by the cylinder balancing routine. Fuelling adjustments are limited to 10% which would be approximately 4mm at 750 rpm. If adjustments of greater than 3mm are being applied, then the cylinder condition will need to be checked.

My cylinder 5 is at 5-7 mm3 at idle, but zero over 1000 rpm.

I think checking compression and also pressure testing cooling circuit is called for.

G62 said:

I checked continuity on all wires in the harness and all seems fine. Also the ECM does monitor the wiring I believe and should throw error messages if there was a problem with the wiring. My diagnostic tool reports no errors from the engine, only overfueling in fuel compensation live data for cylinder no5; -5 to -7 mm3 at idle. In addition there is a marked vibration at idle.

Could of course still be the harness so I will get a new one, where can I get one for £60 ?

Click to expand...

I think the loom may be more. It was mentioned on Wheeler dealers when they changed it.

tanis8472 said:

I think the loom may be more. It was mentioned on Wheeler dealers when they changed it.

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Thanks, checked the price at Brit-Car. LR original wiring assy is £165. Not cheap but for sure better than from the LR dealer here in Norway, they wanted almost £400. I suspect the £60 could be the same part from BMW dealer in UK.

From experience here the LR dealer here charges more than double compared to BMW for identical parts. The fun part is the my local LR dealer is also a BMW dealer.

G62 said:

Thanks, checked the price at Brit-Car. LR original wiring assy is £165. Not cheap but for sure better than from the LR dealer here in Norway, they wanted almost £400. I suspect the £60 could be the same part from BMW dealer in UK.

From experience here the LR dealer here charges more than double compared to BMW for identical parts. The fun part is the my local LR dealer is also a BMW dealer.

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That's a ****ter lol