The modern VW diesel engines are a nightmare to work on and fix. Hi

[jaahn]

Hi My mate has had a few VWs and currently has three in the family fleet (and some Froggies).He does all his own work and we help each other, with technical details and practical assistance too. Worked well over the years and now he has a small farm so more machinery to work on. And animals

He has three VW 2lr turbo diesels in the family, a van and two Tiguans. One of the Tiguans threw fault going to work with the daughter, a couple of weeks ago and went into limp. He looked at at it, nothing obvious, cleared the code and it went OK for a couple of days. Then repeat. So he retrieved it and swapped it and drove it to the farm. Slow in limp but started and ran ok if cleared till a hill.

He has the U-beut software, laptop and dongle to read the codes and operate the functions for a VW, Ross-Tech and the forum and Wiki(just like Diabox for PSA). But he has cleaned the manifold of crap, cleaned the valves that were suggested as problems, the throttle body, the throttles ?? etc and it will not go. Changed the battery and checked the setting against the other engine, ran the reddiness checks but no start or codes. He has never had a non start ever. I am helping him by remote but ??

That engine is so complicated and has so many thingies that do this and that and whatever !! It makes a PSA diesel look old fashioned. Currently it is not showing any codes but will not actually start. BUGGER !
Anybody got a match
Jaahn

 

[dimistyle]

Ross-tech now that brings back memories of Passats with stupid error codes.
Im guessing he's disconnected one too many sensors and not reconnected, probably on the manifold or cam, all I can recall is the black soot poring out the exhaust if the MAF was blocked.

 

[jaahn]

Hi dimi he is super careful but there is something not right ??. Some pictures of the engine parts Before and after cleaning suggestions from the forum Wiki.

 

[Whippet]

Hi My mate has had a few VWs and currently has three in the family fleet (and some Froggies).He does all his own work and we help each other, with technical details and practical assistance too. Worked well over the years and now he has a small farm so more machinery to work on. And animals

He has three VW 2lr turbo diesels in the family, a van and two Tiguans. One of the Tiguans threw fault going to work with the daughter, a couple of weeks ago and went into limp. He looked at at it, nothing obvious, cleared the code and it went OK for a couple of days. Then repeat. So he retrieved it and swapped it and drove it to the farm. Slow in limp but started and ran ok if cleared till a hill.

He has the U-beut software, laptop and dongle to read the codes and operate the functions for a VW, Ross-Tech and the forum and Wiki(just like Diabox for PSA). But he has cleaned the manifold of crap, cleaned the valves that were suggested as problems, the throttle body, the throttles ?? etc and it will not go. Changed the battery and checked the setting against the other engine, ran the reddiness checks but no start or codes. He has never had a non start ever. I am helping him by remote but ??

That engine is so complicated and has so many thingies that do this and that and whatever !! It makes a PSA diesel look old fashioned. Currently it is not showing any codes but will not actually start. BUGGER !
Anybody got a match
Jaahn

Hi.

Just to clarify the sequence:

1. Vehicle was running OK.
2. Then went into Limp home mode, but still drivable and able to clear codes, but not much power up a hill
3. Then crank-no start
4. Then clean throttle body and manifold, swap battery etc.

Or was it 4 then 3?

Cheers.

 

[dimistyle]

as error code says connection to exhaust pressure valve which is located under the vehicle between centre and rear mufflers (cat and NOS cleaner) has probably not been connected or broken wiring harness

 

[jaahn]

Hi Thanks for the comments. THE CAR IS NOW RUNNING
He went to bed early, got up early, changed the fuel filter, looked at the filter to check for water, suspicious substances, then rebleed the fuel system using the software for some minutes. Fitted a different battery and after a couple of tries the HP fuel pressure started to get up. Then it started and went. Wife said it sounds better running than before. Phew ! Drives OK on a short trip around the farm and no lights or codes. Stops and starts normally.
He was about to give up and was using that swear word, dealer, yesterday, because he has other work needs doing. It has taken two weeks of work on and off, to get to the end. Bl**y hell complicated and the software did not help much really in pinpointing the exact problems. Only the associated forum and Wiki. Only one code showed at the begining when it went to limp the second time. Only the secondary level engine light warning came on, the preheater light.
When the engine refused to start after checking and cleaning some EGR parts and AFM there were no codes or light. Just the ECU refusing to fuel it, he thinks ! As the suggested list of items to look at/clean, from the Ross-Tech Wicki, got larger the number of things to remove became larger and more difficult to get at. A bit scarey. And time consuming.
He might do an analysis of it later when he has time to reflect and drives the car on the road for a while. But we think it was a combination of items that were a bit on the edge of needing cleaning/work, boost controller valve blocked, crap EGR buildup generally, and unknown factors, that triggered the initial fault. The original fault occurred when the A/C was turned on to demist the car. It has done about 165000km, bought second hand a year ago.
Whippet I cannot be more definitive as I was not there at the car and only advised by email and phone/text.
Cheers jaahn
PS the Ross-Tech VCDS Light free software is much better that Diabox to use and more logical but not perfect either. It will drive the essential items for checking and service, do readiness checks, and read stored data etc. Said to better for the purpose than the VW factory software. You can pay for the full software version and get backup too but not cheap for home use.

 

[COL]

I find with anything modern that runs on a computer and that has diagnostics, that the diagnostics are there to aid the trouble shooting and will not tell you exactly where the problem is. You still have to do the old fashioned fault finding of checking to nail down the exact problem.

Anyway sounds like a good outcome and proves that persistence does pay off, no matter how frustrating the problems can be along the way. to your mate and a job well done. I bet he learned a lot along the way. I think this is called the Hard School of Knocks

 

[seasink]

I wonder if a particle filter problem is hanging around.

Only new VAG-COMs are hard to find. Up to 2010 copies and cracks float around. An interesting similar project is PSA-COM which doesn't fall off lorries.

 

[DoubleChevron]

I doubt this is a VW thing .... it'll be a "all modern very complex diesel" thing They sure aren't simple motors these days!

 

[jaahn]

I wonder if a particle filter problem is hanging around.

Only new VAG-COMs are hard to find. Up to 2010 copies and cracks float around. An interesting similar project is PSA-COM which doesn't fall off lorries.

Hi seasink. The VCDS software allows you to do a forced regeneration driving or stationary. Possibly it will also evaluate the need, by the pressure drop or at least guesstimate a need to do it by stored data, in later models. I think he did a stationary burn or will do so.

Thanks for the kind words peoples. He was getting a bit desperate yesterday. I thought it was a story worth telling here. I have not worked on PSA diesels but looking at them they seem differently designed with less add-on devices to achieve mystery outcomes ! The VW EGR, boost control system is in the pic below(it is slightly non standard)

My rhetorical question is why do diesels now have all those throttle valves. WTF do they do ? I must study the exact reason for each of their use. I have read some

explanations but am not convinced yet.
Jaahn

 

[REN TIN TIN]

Is this one of the famous "dieselgate" VAG diesels?
(Remember them)
Could explain the complicated and/or seemingly unknown function of some components or the 'mystery' outcomes.

 

[Whippet]

My rhetorical question is why do diesels now have all those throttle valves. WTF do they do ? I must study the exact reason for each of their use. I have read some explanations but am not convinced yet.
Jaahn

Hi jaahn.

You poor guy, I can see the signs. I feel for you, it seems your mind suffers the same curisosity and interest in how things work and systems within systems, and optimisation that mine does.

I can't remember my wifes #birthday or wedding aniversary, but I can recall many things that I find interesting, learnt years ago in my early trade days.

It's been getting under control now that I take regular medication for it, three flat whites a day! - and some nice cab sav occasionaly.

# actually I can, but often don't get things organised in time! Thats what you have daughters for isn't it?

Enjoy.

Cheers.

 

[seasink]

The PSA diesels have one or two butterfly valves in the air stream, used to control flow through the intercooler. The intercooler can be bypassed.

The 1.6 engine has two. A quick translation of a document issued by the French tech college system is:

The double metering butterfly is made up of two electric units used to limit or prevent the passage of gases through the heat exchanger during particle filter regeneration and to adjust the pressure difference between intake and exhaust in order to control the EGR flow.

The flaps also muffle the intake during the motor shutdown because of the inertia of the turbocharger. The hot air valve is closed without voltage. The cold air valve is open without voltage.

The 2 litre engines have two vacuum controlled valves or a single valve for cooled air control.

 

[seasink]

This diagram shows the combustion air routing in the PSA 2.0L RHH engine.
Blue is supply air, red = exhaust, green =cooled EGR, yellow actually enters the cylinders.
The vacuum operated butterfly valves are at item 6. Item 3 is the engine computer.

 

[JohnW]

Jees. And I was putting off making a slight adjustment to the R8's automatic choke throttle control. I take my hat off to you all over that modern diesel.

 

[Languid]

Hi Thanks for the comments. THE CAR IS NOW RUNNING
He went to bed early, got up early, changed the fuel filter, looked at the filter to check for water, suspicious substances, then rebleed the fuel system using the software for some minutes. Fitted a different battery and after a couple of tries the HP fuel pressure started to get up. Then it started and went. Wife said it sounds better running than before. Phew ! Drives OK on a short trip around the farm and no lights or codes. Stops and starts normally.
He was about to give up and was using that swear word, dealer, yesterday, because he has other work needs doing. It has taken two weeks of work on and off, to get to the end. Bl**y hell complicated and the software did not help much really in pinpointing the exact problems. Only the associated forum and Wiki. Only one code showed at the begining when it went to limp the second time. Only the secondary level engine light warning came on, the preheater light.
When the engine refused to start after checking and cleaning some EGR parts and AFM there were no codes or light. Just the ECU refusing to fuel it, he thinks ! As the suggested list of items to look at/clean, from the Ross-Tech Wicki, got larger the number of things to remove became larger and more difficult to get at. A bit scarey. And time consuming.
He might do an analysis of it later when he has time to reflect and drives the car on the road for a while. But we think it was a combination of items that were a bit on the edge of needing cleaning/work, boost controller valve blocked, crap EGR buildup generally, and unknown factors, that triggered the initial fault. The original fault occurred when the A/C was turned on to demist the car. It has done about 165000km, bought second hand a year ago.
Whippet I cannot be more definitive as I was not there at the car and only advised by email and phone/text.
Cheers jaahn
PS the Ross-Tech VCDS Light free software is much better that Diabox to use and more logical but not perfect either. It will drive the essential items for checking and service, do readiness checks, and read stored data etc. Said to better for the purpose than the VW factory software. You can pay for the full software version and get backup too but not cheap for home use.

I changed a camshaft on a Golf PD several years ago, and it then refused to start. Nothing would show up on the scanner that was any help, either.
Then, after almost two days of sheer desperation, it fired up & ran like clock. I still do not know why it wouldn't start: it was fully primed, everything done 'by the book'.

 

[jaahn]

Hi
As a post script to this saga, the car was OK for a bit then went into limp mode again but with a fault light and a code this time, that pointed to the turbo controller. He looked there and discovered a dodgy wire splice under some taped connection. Somebody had replaced a part previously and did a poor job. On further examination the turbo diaphram was not holding air either when tested. So he replaced that too (with some difficulty and new half moon spanners). He thought that it had been badly fitted previously and torn the diaphram a bit.

So has this finally revealed the original problem ?? Hope so ! Caused by a sh*t repair in the past that came back to bite the next owner. Hmm. The good news, they all think the car is running very well after the clean out of the manifolds and various devices. Better than the other similar one and better economy too..
Jaahn