L322 TD6 Turbo Overboost and Diesel Leak Problem

Now i know I only usually post a load of BS and random crap on other people's threads but I am in need of some moral and technical support for an L322 2006 TD6 M57 3.0D I have been messing around with for a few months that belongs to a mate.

I have a fault code of P0046 - VARIABLE NOZZLE TURBO NEGATIVE DEVIATION (INTERMITTENT) that is triggered when i accelerate hard up a fairly steep hill and then it loses most of its power like it's in limp mode and the power slowly returns to normal. I can clear the fault and around town and on the motorway it pulls fine but it's this particular hill that runs off a roundabout when i am accelerating from slow speed up the hill that triggers it.

I have read many BMW and Landrover forums and even VW TDI forums in regard to the variable vane turbo, VNT, VGT etc and when I looked at the turbo actuator it was indeed really sticky causing what i have researched to be turbo overboost condition. When I disconnect the turbo actuator diaphragm I lose a lot of the low down power but it does not overboost as the actuator is in the low boost position when no vacuum is applied which is where I believe it should be when the engine revs / demand are high
Convinced the variable vanes were the problem and after running turbo cleaner through it and manually moving the actuator arm which didn't resolve it I decided to remove the turbo and strip it down. Even longer story short, I did this, got the turbo vanes moving very easily and the barsteward still goes into gimp mode

i have already replaced the turbo actuator solenoid control valve, PCV filter and cleaned the MAP sensor so i am a bit stuck as to where to go next.

I am going to fit a new MAP sensor to rule this out, I will clean the MAF and I think I should be checking the pipework post inter-cooler and EGR if i knew where it is and some flaps as well apparently.

I am also considering removing the turbo again and checking the adjustment of the actuator arm length in case it isn't releasing far enough but i have run it with a vacuum gauge in series with the actuator so I can monitor the vacuum applied from the solenoid and the vacuum drops to zero at high demand which means the vanes should be in the relaxed position as they are when i remove the vacuum entirely but maybe not early enough..

I have also found some wiring from the main ECU box that runs along the side of the engine that looks to have dropped down by the exhaust manifold at some point and the outer sleeve has melted so this is also on my check list.

Now there is another twist in that after replacing the turbo I wanted to check for oil leaks and noticed it has a rather heavy leak of what i believe to be diesel from the other side of the engine above the alternator.




I am very retarded when it comes to diesel engines, amongst other things of course, so if anyone can suggest anything i can try and also a possible source of the diesel leak it would be much appreciated as this is starting to drive me nuts.

I took a week off to play with my 4.4 and weld the exhaust and generally take it apart and put it back together again and all I have done is feck about with the TD6 and somehow put a new fuel filter on a TD5 Defender, probably because it looked like I didn't have enough going on.

Anyway writing this out I shall treat as therapy even if nobody has any ideas.....

Thanks for reading this if you did, if you didn't i don't blame you
Andy

Oh HC, you know we all have a soft spot for you, (apart from Alan of course)

I'm like you, Diesel dyslexic, but only because we have not had enough experience on the manky evil contraptions!!!!


There is one thong, I mean thing that these common rails need and that is the Aux fuel pump, if that goes south you WILL get limp mode on inclines or when giving it the beans.

Diesel leak? What I always thought was the FBH on the N/S inner wing is actually a fuel cooler. What side is the Alternator on the TD6?
I bow to superior knowledge......hence the dicky back!

Thank you for your input..... I know the m62 like the back of Alan's hand but i am stuffed when it comes to the diesels and there are quite a few posts referring to the primary and secondary fuel pumps that can cause this issue but i had forgotten about those as I have been focused on the turbo fault code but in reading a number of threads regarding the P0046 code it has been caused by non turbo related problems so those pumps should be added to my list. I am wondering if the high pressure pump and the mentioned leak are causing the problem..
We have run live data on my faultmate and checked the low pressure and high pressure circuits which appeared ok though, the low pressure reading does drop but not to below what would be considered a problem from what i can tell.

The alternator is in a similar place to the M62, on the right hand side at the front when standing looking at the engine scratching your head

So the alternator is directly below the FP then, and you have leaking diesel onto the alternator?
Haven the foggiest then, soz.

I'm more interested in the welding of your exhaust on the 4.4, is it made from a type of stainless steel?
I hear it can be welded with regular Mig, pray tell....

myfirstl322 said:

So the alternator is directly below the FP then, and you have leaking diesel onto the alternator?
Haven the foggiest then, soz.

I'm more interested in the welding of your exhaust on the 4.4, is it made from a type of stainless steel?
I hear it can be welded with regular Mig, pray tell....

Click to expand...

In the pic i attached, the top right wicker basket looking thing is the alternator, the pic has rotated when i posted it and the leak is going down behind it so i think that is going to be in the area of the HP Pump although everything seems to be hidden below the inlet manifold.

The exhaust is a stainless steel although i don't think it's a great one as it is showing signs of corrosion. I have a gasless mig welder although only a small hobby 100 amp thingy but it is ok for patching stuff up. I have flux core stainless mig wire that I purchased from the USA but I will probably just use what's in it which is 0.8 steel flux cored as the amps are a bit low for the stainless. The welder is a little light weight but I think the exhaust has a crack along a seam so I'll give it a go and see what happens. It is along the edge of one of the CATs which i believe was a recall up to a point. I suspected my CATS of being blocked after checking with a laser thermometer anyway so the exhaust is coming off to check with my borescope, well the upper ones anyway as i believe there are two each side. You can weld stainless with mild steel wire it just wont be stainless so can rust.
I have had a TIG welder on christmas list for a few years but Santa doesn't seem to think I have been good enough.

This is the live data showing the manifold pressure and also the low and high pressure fuel readings, this may not have been when it went into overboost though as the software kept resetting itself.

I'm struggling to get a sense of what's happening, or not I'm afraid.
Is it possible to change the way it displays, like all the readings as lines maybe?

That's all you get with faultmate, the top left is boost pressure or manifold pressure from the turbo, you can see vehicle speed as this was taken when driving with my mate on the laptop next to me, low pressure supply is the low pressure fuel reading which I think shouldn't drop below about 300, you can also see the high pressure fuel line reading. The cylinder roughness is the rpm for each cylinder, and i believe the values differ slightly to compensate for smooth running, but basically it is the rpm. The throttle demand is how far down the throttle is.
It is just a table for values I gave never managed to get it in any better format or the fancy graphs you see on some threads.

Get the fuel leak sorted first would be my advice Andy. Weasels don't like air in the fuel system.

That's a good call mate, i'll do that, it is trying to tell me something i'm sure.
I'm guessing the overboost code of too much air could be read the same as not enough fuel..