My guess is you have exhaust leak. Do you get smell in the cabin during warm up or when stopped? Do you have VCDS to check the DPF ash load? Common leak points are exhaust manifolds, turbo flange and so on. Mine just had a manifold replaced under the extended warranty.

 

Thanks - will look at that. No smell in cabin at all. I don't have VCDS but starting to think it would be wise to get one.

 

Hi everyone - the diesel specialists believe this was the problem. They have cleaned the throttle body and believe that the problem has been solved for the time being. Apparently the rest of the inlet system is similar and will require removal and cleaning. This is my first diesel and I certainly have a lot to learn about the modern diesel engine.

 

I have the same problem, is it just carbon buildup? and how much did you spend on cleaning it?

 

Carbon buildup is a thing, especially on direct injected diesels, and has been discussed all over the internet.
EGR deletes and other approaches can sometimes reduce the frequency of physical cleaning requirement.

 

Thanks everyone for your contributions

The problem was diagnosed by VW dealer as being faulty injectors – 3 of the 6 and quoted in excess of AUD$8500 to fix the problem. I sourced replacement Bosch injectors myself – approximately AUD$400 each and had a specialist diesel service centre replace them, believing VW were way over the top in their quote. The injectors were replaced and it made no difference. Upon further investigation by the independant diesel specialists it was discovered that the entire inlet manifold was ‘sooted’ up, with the throttle body being barely able to work – see pic previously posted. They cleaned what they could – cost AUD$1000 – and made these recommendations:

• The entire manifold system required removal and cleaning up and
• Install a ‘catch can’ to prevent the build-up in the future
• Spend the extra on only using premium quality diesel fuel and filters

I removed and again cleaned what I could and the only thing remaining is the inlet manifold, which is very difficult to remove for a non VW trained home mechanic. Though not tested, they felt that there was nothing wrong with the old injectors, but fitted the new ones anyway.

The catch can has been installed – there is a Provent kit in Australia designed specifically for the Touareg – and it now runs exclusively on premium low sulphur diesel fuel. The end result is that it runs nicely with better fuel consumption. A side story is the stop-start system has now recommenced working. There is still a bit of a sulphur smell but I think this will probably disappear when I get the inlet manifold cleaned properly by my local mechanic, who did his apprenticeship with VW.

So my advice is this:

• Don’t take your car to a VW dealership – instead go to a specialist diesel service centre
• Remove and thoroughly clean what you can of the entire inlet/emission control system
• Install a quality ‘catch-can’ – everyone take notice of this – do it from new
• Use premium quality diesel fuel
• Use genuine air, oil and fuel filters
• Only replace the injectors if you are advised to by a specialist diesel service, not VW.
• After this experience, it is highly unlikely that my car will ever be taken to a VW dealership in the future.

Good luck, Treg friends.

 

If only techs/mechanics/specialists would spend half the time they spend telling stories about their expertise on the actual diagnostic, it wouldn't cost poor owners this much.

We have the tools/technology/knowledge to isolate and identify stuck flaps, overcompensating injectors, carbon buildup, etc.

These engines/systems are full of sensors that will give you clues at what to dig into.

 

VW says they tested everything and were able to diagnose the problem through the use of their testing equipment. However, neither the diesel specialist or my own mechanic could not find any faults which would cause the problem, and the engine management light did not come on to warn of some failure with a sensor. It was only through good old school mechanical work of disassembly of each component and checking and cleaning it manually that the problem was located. The engine still has an occasional rough idle and there is still some sulphur smell at times and I hope this disappears when funds allow me to have the entire inlet system removed, cleaned and re-installed. I have seen that there are aerosol sprays which can be used to de-soot the inlet system. I have been warned to stay away from these as they generally do not work on excessive soot build up and may lead to damage in the future. However, my guys tell me that they can have a use in a preventative way if used regularly. Deleting the EGR is not an option for me in Australia - it is likely that it will be detected by full inspection if ordered by Government authorities or void insurance cover in the event of a claim on my insurance. Hope this helps those out there experiencing similar problems. I must say that my Treg, even with over 160000km on the clock, is the best car I have ever owned - luxurious and high performance are its standout features and when towing our 16 foot caravan, you have to keep checking the mirrors to confirm that it has something attached to it. If only we could add some kangaroo protection to the front in the form of a bullbar or nudgebar! I know it wasn't build exclusively for Aussie conditions, but if only....

 

There a guy in Tasmania I think posting here that been working on a bull bar

cheers
Rohan

 

Thanks Rohan, I will keep an eye out for posts surrounding this issue - it will need to look the part for me to consider getting one. In the meantime, I have a Shoo-Roo fitted - don't know if it works but haven't hit a roo, and also fitted an LED light bar to give me a bit more light down the road for early warning. Thanks for your post, mate

 

"If the manifold has buildup on it, it doesn't contain any moving parts to jam up"

The manifolds near the inlet ports to the head have swirl flaps in them in addition to the inlet butterfly valve at the manifold inlet and these can gunk up with carbon / oil and really require the manifold to be removed for cleaning if badly fouled.

If they seize up it should throw and error as they use an electric actuator

cheers
Rohan

 

On the gen 1 engines... Look up his gen.... I'll wait.

 

In first post it says 2015 180kw V6 TDI - I believe that has the swirl flaps ???

 

The CRCA (which I believe is what he has), is the 2nd gen equivalent\version of the CNRB we have on this side of the pond... as such, I believe this is the setup he has (it also coincides with pictures he's already shown)
As you can see, the swirl flap shown in post #4 is the only potential "flap" that could be all jammed up.

 

I stand corrected .....

 

Your V8 has them, so I can see how you might've got mixed up.

 

Later V6 engines also have them like my 2013 V8 and I assumed the 2015 V6 engines did. To many variants to keep track of

 

Negative. Ssp350 is about the 1st gen (as per your extract)

 

Thanks everyone for your feedback - unfortunately in regional/remote NSW (Australia) there are very few options as to who to trust to give the right advice. The nearest VW dealer is more than 200km away. The nearest diesel service specialist (who I have been speaking with) is approx 250km away. I can see that any build up of junk in the inlet manifold will only restrict air flow, but it has a fair bit in it which is why I will have it removed and cleaned - when finished, it should improve air flow and make the engine far happier. I have had a quick look inside the opening of the inlet manifold and it has evidence of 160000km of junk in it. The sensors have been checked as far as I know are all OK and as I said no error messages. Thanks again everyone.

 

How will they be "cleaning" it? By what process?

 

Not sure at this stage - will find out before I give them the go ahead. I have been told by others that the best way is to manually clean very carefully with a brush and soapy water.