Limp Mode (no management lights), reduced power following engine restart.

[d4n93rm0u53]

This question relates to a VW Golf Mk5 2.0 TDI, circa 97k miles (35k under my ownership), most of which has been urban travel (trips <5mi) although it does have a decent run out every few weeks (>25mi @ 60+mph).

So as the title implies I've just experienced the dreaded "Limp Home" mode, an engine restart reengaged the turbo but I do seem to have slightly less power than before. The turbo is definitely there, but it doesn't kick in like before ...its a far more sedate and relaxed acceleration experience, in short things feel slow and I'm lacking confidence.

There was a brief hiccup immediately before limp mode kicked in, this occurred shortly after starting my journey and on an uphill section of the road. No error lights were displayed on the dash, nothing at all to indicate a problem other than the obvious lack of a turbo.

I haven't managed to find a local garage with the right equipment to read the ECU, should I even expect to find any error codes listed if the dash didn't display anything?

For sure I've Googled the interweb in search of answers, but nothing seems to describe this exact scenario.

Does anyone have any thoughts? Could this be a DPF, vacuum hose or solenoid/actuator related issue.

Final comment before I submit this post - I've had a cursory look around the engine bay, there's a small amount of oil kicking around some of the pipework and engine block. But this is obscured by the engine cover (which I haven't yet removed), hence I'm unsure of the source.

[joca]

I had a similar trouble with mine and a local garage found the turbo pipe had come off. They refitted it (with 2 self tappers as it came off again)
I nearly pee'd myself as I was pulling away at lights at the time and car lost all power and a loudish noise I thought something had broken on the rear drive shafts.

[d4n93rm0u53]

Yeah - I have had that issue myself, albeit with another car.

I'm guessing this isn't quite the same, but only because I've recovered some power without physically doing anything to resolve the problem. Could be a split pipe though I guess, some posts I've seen suggest that issue is hard to diagnose when the system isn't under pressure.

[joca]

Yes, makes sense. Not easy to see it though. Hope that's all that is with yours. [emoji6]

[Doctle Odd]

It's probably over boosting and that will put it into limp home mode. You need a diagnostic scan look here for someone near you with vcds https://www.google.com/maps/d/viewer?ll=56.231139,-2.779541&iwloc=0004c505cfcb6158e0447&msa=0&spn=3.493691,10.821533&mid=zwQHurSsCMz8.kMTwqF0PoXwc

[DMitch16]

Perhaps your turbo vanes are stuck or the vane ring is sticky. I've had the "burp" before, a sudden jerk as if something has broken, then limp mode with no light but out of the many things that have gone wrong with my engine I can't recall which bit was causing this issue.

[d4n93rm0u53]

It's probably over boosting and that will put it into limp home mode. You need a diagnostic scan look here for someone near you with vcds https://www.google.com/maps/d/viewer?ll=56.231139,-2.779541&iwloc=0004c505cfcb6158e0447&msa=0&spn=3.493691,10.821533&mid=zwQHurSsCMz8.kMTwqF0PoXwc

That's a great resource, plus there's someone not a million miles away from me!

Over boosting would make sense, its been an especially speedy motor for quite some time ...haven't had it remapped or anything nefarious, but in the past you would feel the turbo kick in at around 1900rpm. Whereas now it's more gradual, perhaps a little bit of extra boost around 2500rpm (but nothing exciting).

I half wonder if current performance is in keeping with the original engine spec, maybes this issue has been brewing for a while now.

[d4n93rm0u53]

Perhaps your turbo vanes are stuck or the vane ring is sticky. I've had the "burp" before, a sudden jerk as if something has broken, then limp mode with no light but out of the many things that have gone wrong with my engine I can't recall which bit was causing this issue.

That's interesting, did you notice any decrease in engine performance (power) post "burp" ...and if so, I wonder if everything return to normal without further intervention.

[Crasher]

What is the cars year and engine type code?

[d4n93rm0u53]

What is the cars year and engine type code?

Registered June 2006, engine code BKD

[Crasher]

It won't have a DPF and in the vast majority of cases, a BKD with these symptoms needs a turbo rebuild, we do loads of them.

[d4n93rm0u53]

That sounds nightmarishly expensive! When you turbo rebuild, is that on account of mechanical failure or simply carbon buildup?

I was half hoping this was something simple like a split pipe, particularly since I can see fresh signs of oil on the engine block. For the moment it remains drivable, but I do need to kick down an extra gear when going up steep inclines.

[d4n93rm0u53]

...just as an aside, its worth mentioning that a new turbo was installed under warranty at around 65k.

[joca]

It won't have a DPF and in the vast majority of cases, a BKD with these symptoms needs a turbo rebuild, we do loads of them.
I have a BKD 2006 140 engine and I assumed it had a DPF?? how can I tell if it has one?

[Crasher]

...just as an aside, its worth mentioning that a new turbo was installed under warranty at around 65k.

You need to get a fault code read done to see why it is going into limp mode.


I have a BKD 2006 140 engine and I assumed it had a DPF?? how can I tell if it has one?

The only way a BKD would have a DPF is if someone had the retrofit kit installed and I have never even seen one. Anyone who did that would need their bumps feeling....

[joca]

You need to get a fault code read done to see why it is going into limp mode.



The only way a BKD would have a DPF is if someone had the retrofit kit installed and I have never even seen one. Anyone who did that would need their bumps feeling....
That's great. I assumed it had one after reading my manual. [emoji4]
As I am very borderline on usage for a diesel, even worse with a DPF, that's good to know.
Thanks

[d4n93rm0u53]

You need to get a fault code read done to see why it is going into limp mode.

For sure you're absolutely right, am in for an MOT next week so I'll wait and see what that turns up before contacting someone with the appropriate equipment.

I've been out over lunchtime, was actually starting to think things were returning to normal. Performance was returning, but suddenly the same loss of power and then limp mode. I noticed that without the turbo acceleration didn't feel linear, as if there was a flat spot of sorts. Could be normal for a non-turbo diesel, I'm not sure.

I'll laugh (or cry) if this turns out to be a fueling problem, topped up at Tesco a few days ago.

[DMitch16]

I bet your inlet manifold, EGR valve and anti shudder flap are caked too. Took mine off at 100K and had at least a half centimetre deep coating inside the manifold, the EGR was thickly coated (soot plus oil vapour in the intercooler = sticky mess in the intake parts). Cleaned them all thorough, reassembled and car was lovely for the next 50K. Just repeated the clean to get rid of the subsequent build up and I'm sure I've got some horses back. Fuel economy back into mid forties (and I boot her 20 miles to work on occasions and still get over 40mpg every time).

I'd also be wary of my oil pump drive at 97k if it has not been checked. You possibly have the chain drive system which is a weakness for your year of car and the oil pump drive key in the balancer unit will also be closer to failure. I've not yet seen a good drive key on a car over 100K and they all had varying stages of rounding due to the design. Mine went at 148,000 after a service where I WAS going to check it and DIDN'T! After sorting it I'm 10K further on so consider myself very lucky indeed as I still have a sweetly singing turbo and only a £125 hole in my pocket as I managed to get an modified exchange balance shaft and new key.

[Crasher]

Half a centimeter, thats nothing!

http://i222.photobucket.com/albums/dd20/Crasher1964/Blockedinletmanifold_zpsce855545.jpg (http://s222.photobucket.com/user/Crasher1964/media/Blockedinletmanifold_zpsce855545.jpg.html)

[joca]

Wow... What bit is that?.?

[Doctle Odd]

Wow... What bit is that?.?

That's Crasher's :notworthy mind :1zhelp: (Mine when the wife wears a short skirt too)

[Crasher]

Wow... What bit is that?.?

That's the inlet manifold behind the EGR valve from a 1.9 TDI T5.

[d4n93rm0u53]

Well its now a trivial to force limp home mode, whereas before I needed to attack a hill. Now its simply a matter of pushing along while on the flat, fortunately light throttle use and a low gear is sufficient to get up hills.

Have found myself a local shop with the kit necessary to read my ECU (Professional Auto Electrics), actually I've used these guys in the past and they are pretty good at diagnosing faults.

If this is a coked turbo, as most people suspect, then I may consider removing and cleaning the internals myself ...found what seems to be a good in depth online guide http://goo.gl/5YHGVN

Of course I'll report back regarding the outcome!

[Crasher]

That write up makes no mention of removing the right hand drive shaft, you won't get the turbo out of a BKD engine bay without doing that.

[d4n93rm0u53]

That write up makes no mention of removing the right hand drive shaft, you won't get the turbo out of a BKD engine bay without doing that.

Perhaps there are more differences than I thought between the Golf and A3, that's a pain.

This post (http://goo.gl/OR9FSi) (relating specifically to the BKD engine) implies that you can get away without removing the drive shaft. But I get the distinct impression that you've done a few of these, which probably means you mention removing the drive shaft for good reason?

[Doctle Odd]

Crasher has done more turbos than you could shake a

28388
at

[Crasher]

We do lots of them but the A3 and the Golf 5 are identical, we have never been able to get one out of there without removing the driveshaft.

[d4n93rm0u53]

....the A3 and the Golf 5 are identical...

Embarrassingly I have failed to mention one very important fact about my Golf, yes its a 4Motion! Online guide's don't mention the extra 4x4 gubbins, this had not occurred to me until now.

Anyway all that aside, the results are in! Code P0299, which I'm reliably informed is an intermittent (under) boost fault. I've since removed the engine cover to investigate the oil residue mentioned earlier in my post, but naturally I have no idea what I'm looking at.

I fear its time for some additional research!

[joca]

That's the inlet manifold behind the EGR valve from a 1.9 TDI T5.
Have you seen these problems on the 2.0 variant??

[Crasher]

Just had an A3 170PS in this morning (BMN 2 litre 16v) for new inlet manifold and the system was solid, up to it's knickers in gunk. It took two hours just to clean out the flap, EGR valve and head inlet ports, yuk :boggled:

Getting the turbo out of a Golf 5 2 liter 4-Motion engine bay is an utterly appalling awful nightmare of a job, the rear prop and transfer box make it a total sketch, I am not joking when I say we find it easier if we are lucky enough to be doing a clutch one one. In fact when we do a clutch on a 2 Litre 8P A3Q or Golf 5 4M, we strongly recommend the turbo is rebuilt whilst the box is out.

[d4n93rm0u53]

Urgh, nightmare!

My plan for tomorrow was to remove the engine tray and check boost/vacuume pipes for splits, but I'm now wondering if that's going to be feasible. Can you advise whether I'll be able to access the turbo, physically and visually?

Most of what I've read today suggests that turbo failures generally manifest with over boost, which is the opposite of what we have here. That said quite a few people online seem to have given up on resolving their P0299 fault, or they have simply run out of money. I'm currently pinning hopes on pipe work or a stuck actuator.

[Crasher]

16683 (P0299) - Boost Pressure Regulation: Control Range Not Reached

I would agree that this code is normally either a boost leak or a vacuum control system problem rather than a fault with the turbo itself as they don't often stick in a position that would result in this error, but it can happen.

In your car's case it is often the intercooler outlet on the cars left into the right angled pressure hose (15) in front of the gearbox, often the intercooler snaps on the lip which retains the spring causing the pipe to partly blow out and leak boost or it can just be the ally retaining barbs on the hose ends that have worn on the clip. Even the clip sometimes snaps.

http://i222.photobucket.com/albums/dd20/Crasher1964/BKDcahrgeairsystem.jpg (http://s222.photobucket.com/user/Crasher1964/media/BKDcahrgeairsystem.jpg.html)

Sometimes number 10 blows off, like earlier today....

http://i222.photobucket.com/albums/dd20/Crasher1964/V157%20flap_zps87lxjbog.jpg (http://s222.photobucket.com/user/Crasher1964/media/V157%20flap_zps87lxjbog.jpg.html)

[d4n93rm0u53]

Well now that's valuable advise, alrighty I'll take a look-see tomorrow afternoon and report back to the forum. That said I'm assuming this area will be accessible once the tray is removed, hopefully it is and I'll be able to check for damage.

Muchas gracias.

[joca]

Crasher you're making me want to sell my car now.... [emoji25]

Any tips to stop it getting clogged up??

[DMitch16]

Hahaha, nice picture Crasher, I've seen worse too so much build up on one that it was difficult to comprehend how the car had kept running. Vile stuff simply vile. Not allowed back in the house until I've been pressure hosed down!

[d4n93rm0u53]

Removing the engine tray yielded a much improved view of things, but frustratingly I'm no closer to resolving this problem. I couldn't see any perished or otherwise damaged vacuum pipes, admittedly some are difficult to check thoroughly due to their location ...but for the most part I'm happy they're all in good condition.


16683 (P0299) - Boost Pressure Regulation: Control Range Not Reached

In your car's case it is often the intercooler outlet on the cars left into the right angled pressure hose (15) in front of the gearbox, often the intercooler snaps on the lip which retains the spring causing the pipe to partly blow out and leak boost or it can just be the ally retaining barbs on the hose ends that have worn on the clip. Even the clip sometimes snaps.


This was an interesting area to explore - I became immediately aware of (what I thought was) significant oil buildup around the joint. There also seems to be play in the joint, certainly more play than exists with any other joint along the boost section of the turbo pipework. Given the oil buildup I'm guessing that some boost is being lost here, but probably not enough to cause the problem described.

28406


28407

Otherwise I did manage to get my finger on the actuator, there was some movement when I pushed down using my finger (probably 5~8mm or so). I note that other online guides suggest using an external vacuum source to achieve the same effect, but I don't currently have access to the necessary equipment.

One pipe on the turbo inlet does have a small hole, more specifically in the corrugated bend section on top of the engine. There's a metal clip which has eaten into the plastic, but presumably this isn't going to affect boost performance (its not a blockage after all).


I've been out for a drive since doing all of this, while performance isn't back but I have found limp home mode far less easy to force.

[DMitch16]

A hole in the inlet will make a difference especially if it is after the MAF as it will be drawing a small amount of unmetered air.

[d4n93rm0u53]

I wondered about this, however since this is an under boost problem my assumption was that additional air intake probably wasn't going to be my issue. Previously I removed the MAF to see if this made any difference, but power delivery was just the same and limp mode was still occurring under heavy load.

Do we think this is something I should be re investigating? I'm currently out if ideas.

[DMitch16]

Wrap some strong tape around the pipe covering the hole and see if there is any difference. Could be a leak in your actuator diaphragm. I use a hand held vac pump that I bought for £20 on the Internet to check vacuum pressures and for vacuum leaks (has been useful for other jobs too).

[d4n93rm0u53]

I'll try that, although given the location its likely going to be hard to achieve a decent seal.

With regards the vacuum pump, they do seem cheap and could help narrow down (or rule out) certain components. Do you know if there's a way to diagnose a faulty N75 with these pumps (or rather their attached gauges), not sure if they function in the same way when the car is stationary?

[Crasher]

If you had a vacuum pump issue you would feel it in the brake pedal effort. That oil buildup and movement around that pipe is normal. It can get to the point you need to do a pressurized leak test to discover where the leak is, I have one to do later today.

[d4n93rm0u53]

Still trying to get my hands on a Mityvac.

In the meantime I've noticed something new, it's a rattle not so unlike that of a loose heat shield. Can only be heard when driving over bumps and curiously isn't noticeable immediately from cold, takes a minuite or two after setting off for the rattle to start occurring. My car has recently (this week) passed its MOT, could be that something was dislodged during that exercise.

Can't see anything loose underneath the car, exhaust wise I mean, it's actually very tidy under there!

Anyway, the hunt for the cause of my P0299 error continues...

[d4n93rm0u53]

Unfortunately I haven't had time to investigate this issue myself, hence my local garage took a look instead. Their findings remain inconclusive, although I'm painfully aware they haven't checked everything yet.

As luck would have it they've their own VAG-COM setup, which if nothing else, verified the P0299 error reported by the last outfit.

Initially they worked on "loosening" off the wastegate, on the basis that they couldn't hear any hissing to suggest a blown intercooler/hose. But this didn't resolve the problem, or improve things even in the slightest. Next they cycled the EGR/Turbo actuators via the VAG-COM interface, but due to lack of visibility we were purely listening for the sound of something happening rather than observing. Curiously I couldn't hear anything, other than for a constant whine coming from the vacuum solenoid assembly.

I should mention that it was late in the day and so the mechanics hadn't an opportunity to remove any intake hoses and really observe what was going on, although they had my car all day. Hopefully I can arrange for them to have another look later this week, or next if they're still super busy.

In the meantime I have some more questions for those of you still willing to advise.

1. When actuators are manually manipulated via the VAG-COM interface, should the engine be running? These components are vacuum dependent, which I assume is generated by some mechanical means.

2. I've noticed that power output and the likelihood of "limp mode" varies significantly from journey to journey, but this isn't an absolute downward trend per se. Should I expect more consistency in the event of boost leakage (i.e. blown hose), or could this be a case of different atmospheric conditions putting more or less load on the turbo?

3. When changing gear there is the usual audible dump of boost, in fact it sounds just like it did when everything worked correctly. Obviously I'm no mechanic, but my understanding of the VNT turbo is that traditional wastegates are replaced with variable vanes. Assuming that is correct, am I safe to assume that my turbo actuator is functioning in some fashion given the audible boost dump?

4. Should I rule out EGR valve failure on the basis that a blockage would likely see an overboost, or should this still be an area to investigate? Note: I'm presuming the boost sensor is pre-EGR.

[d4n93rm0u53]

...
4. Should I rule out EGR valve failure on the basis that a blockage would likely see an overboost, or should this still be an area to investigate? Note: I'm presuming the boost sensor is pre-EGR.

...and I've completely misunderstood how this works, but it seems a sticky EGR valve could cause problems when stuck open? Not sure if this could relate to an underboost error though.

[Crasher]

When operating the VNT actuator in Basic Settings 011, the engine should be running so you can see the boost change at raised idle, in output tests you can do it either way to help you with diagnostics.

Underboost is usually a vacuum leak in the control system which varies in extent according to engine type and year even down to a specific model variation. The right hand drive Golf 4/Leon 1, 150 PD TDI with the ARL engine suffer this due to their specific vacuum pipe arrangement which makes the vacuum supply hose rub on the plastic servo vacuum pipe and it wears through, stopping any of the vacuum system components working.

The noises you can hear to me are more indicative a a 2 litre BKD engine with a turbo that has problems.

[d4n93rm0u53]

When operating the VNT actuator in Basic Settings 011, the engine should be running so you can see the boost change at raised idle, in output tests you can do it either way to help you with diagnostics.
...The noises you can hear to me are more indicative a a 2 litre BKD engine with a turbo that has problems.

Thanks Crasher - Although I really hope this isn't the case, actually the most interesting symptom of all is the lack of any real audible difference in turbo operation (well, apart from it being quieter under load). The guys down at my local garage suggested the actuator arm was moving freely, so I'm assuming that means no sticky vanes. But applying your logic this could still be an actuator issue, or as you said earlier something else vacuum related ...the latter of which does seem to be indicated (web-wide) as being the most common cause of an underboost problem.

I'm more than a little concerned re the diagnostic abilities of my local mechanics, I don't really want to fall into the trap that so many others have faced. I don't want this to turn into an unnecessarily costly exercise, replacing numerous components in an attempt to randomly discover the root cause.

[d4n93rm0u53]

Quick update ahead of tomorrows next home investigation.

So today has (for the first time) seen my car without any sign of a turbo, its practically impossible to hit 30mph up even the mildest of hills. Sadly I live at the bottom of a very steep bank, which my daily commute requires me to tackle. I've got my hands on some ramps and a length of vacuum hose, hopefully I can finally test out whether my turbo actuator is functional.

For now though I would love to know whether complete vacuum failure would result in what I'm experiencing, by which I mean no boost at all ...nada, absolutely nothing at all!!! It's an awful drive, would hate to be following me anywhere. Does/should the turbo spool up at all without any vacuum?

Just to clarify I've not heard any unusual whining since first reporting this issue, there's been no real smoking from the rear either. But that rattle I mentioned a few posts ago, its much worse now. Very noticeable when driving over rough tarmac, still sounds like a heat-shield but I have no idea of the source other than it definitely coming from the front/engine bay area (could be unrelated).

Have researched replacing the turbo in my 4Motion - Urgh, what a nightmare! Wondering if I'm right to think that its extract-able by removing the EGR cooler? If anyone has done this can you confirm whether the EGR cooler must be completely removed from the engine bay, or is it possible to unbolt the unit while leaving the coolant pipe still attached? Guessing not, but this would make life easier and less messy for me as an amateur.

As always any and all good advise is very much appreciated.

[d4n93rm0u53]

...and here are my findings:

After removing the turbo actuator vacuum pipe and then attaching another, I was able to successfully move the arm by applying significant suction. Admittedly there wasn't much movement, but something never-the-less. In my mind I've now ruled out the actuator diaphragm since it easily held a vacuum, and for sometime too.

That lack of travel had me worried though, so I pressed down on the arm from above with a spanner. Movement was significant and very smooth, but wow that internal spring must have some tension behind it! For kicks I started sucking on the vacuum pipe again, just to see if I could hold the arm in its most extreme position. This I was able to do and everything remained in place until I released the vacuum, after which point the arm returned to its original position.

I'm now thinking that I've ruled out the turbo, or at least the vanes. Since I haven't heard any whining, or otherwise weird turbo noises I'm assuming this isn't a bearing issue either. Does that sound reasonable to everyone, or have I missed something in my diagnosis?

But this must be a vacuum issue, because I can't hear my turbo spool up (very much) and there's no audible sound (hiss) indicating lost boost. Which moves me onto the N75 solenoid block and associated components.

Can anyone advise, how would I go about diagnosing this as being the root cause? Do I just buy one and try fitting it, or should I be looking elsewhere first?

[d4n93rm0u53]

Its possible that I'm now alone on this thread, perhaps people have temporarily run out of ideas or aren't currently able to respond. Regardless and for those of you experiencing problems in the future I'll continue to post updates, who knows this may help you in some way.

One of the things I didn't do yesterday was replace the vacuum pipe from the solenoid block to the turbo, so this afternoon I did just that. Didn't notice any change, but at least I've now ruled out pipe collapse.

Actually saying that I haven't noticed any change isn't strictly true, today I've heard more of my turbo ...its still there, just very quiet and subdued! Again it doesn't sound unhealthy, it just isn't spooling up very much.

I've spent sometime underneath my car now, feel much more comfortable with what I am looking at.

Another oddity which I mentioned earlier in this thread was that rattle, its really annoying and quite audible with the windows down (you'll certainly hear me coming). Curiously I cannot find the source, I've tugged on heat shields and inspected the engine bay for loose components but nothing has jumped out at me.

Which makes me wonder if it could be something well hidden, like say a catalytic converter?

However removing the CAT for investigation looks like a PITA, that tricky 4Motion propshaft and transfer box are right in the way. Tapping on the sidewall with the back of a screwdriver didn't help much, probably because of a reluctance to tap too hard and also because of poor access. Not sure if I am barking up the wrong tree with this idea, but it occurs to me that a broken/blocked CAT could impede turbo function.

[d4n93rm0u53]

Turbo's back baby! But with a surprise plume of soot, and I mean a huge cloud of dusty nastiness.

This all happened within the last 100 meters of my morning commute, so I've no idea whether this situation is permanent or if my problem has worsened. I should mention that there was a lot of boost, felt like a rocket ship. It has been a while since I last enjoyed turbo assistance and sadly I had to pull up at work before I could experiment further, so hopefully I'm not in the new position of an over-boost problem.

[joca]

First of all, thanks for keeping updating the thread. Many people don't bother.
Hope you somehow managed to sort out your issue.

[Crasher]

Have you been able to do an output tests control and Basic Settings test on the turbo using a diagnostic computer yet?

[d4n93rm0u53]

...Hope you somehow managed to sort out your issue.

Thanks, unfortunately since I haven't done anything I'm guessing this is just another symptom.


Have you been able to do an output tests control and Basic Settings test on the turbo using a diagnostic computer yet?

Frustratingly no, not yet - I've had problems getting booked in with a local garage sporting VCDS, furthermore my usual garage use a desktop PC (not portable) and they do not have a 4x4 rolling road. Could that be a problem, or can this test be performed at standstill?


In other news I've just gone for another drive. I'm definitely experiencing over-boost, kicks in at around 1700 rpm and there's no letup. Weirdly I did loose the turbo again for a short period, but then it came back just as before (minus any soot). Thought I was back in limp mode at first, but interestingly I didn't need to restart the engine.

So is this a sticky vanes issue after all, or could the ECU be overcompensating for the underboost problem I had earlier?

[Crasher]

You don't need a rolling road or the PC to be mobile, just as long as it can plug in and then the output tests and Basic Settings tests can be carried out to see if the arm is moving as it should and the correct amount of boost change is observed.

[d4n93rm0u53]

You don't need a rolling road or the PC to be mobile, just as long as it can plug in and then the output tests and Basic Settings tests can be carried out to see if the arm is moving as it should and the correct amount of boost change is observed.

Sadly I'm still at work, hence options are currently limited ...so I have tried something far more crude, I've clamped the turbo vacuum line in a vain (yes, I know) attempt to prevent vane actuation.


So is this a sticky vanes issue after all...

Looks like! Full boost, even without vacuum.


Now what, do I attempt the so called Mr Muscle cleaner fix? Actually I'm not sure whether I can get to enough of the turbo to attempt that potential solution, guessing it'll be an EGR cooler out affair (or worse).

Penny for your collective thoughts.

[Crasher]

Don't do the oven cleaner method, it rots the seals and makes the turbo fail, filling the exhaust with oil. The turbo needs to come off for a rebuild.

[d4n93rm0u53]

Don't do the oven cleaner method, it rots the seals and makes the turbo fail, filling the exhaust with oil. The turbo needs to come off for a rebuild.

Fair comment!

I've seen references to home rebuilds, or at least strip down and cleaning of the vane assembly. Even though I haven't tackled anything like this before I am quite keen to give things a whirl, but would like to know what people think about my chances ...remember this is a tricky 4Motion and so turbo access is horribly restricted!

Previously I asked whether removal of the ERG Cooler would provide sufficient enough access to pull the turbo out from above, can anyone advise me?

[Crasher]

You cannot get the turbo out from around the back even with the EGR cooler off, there isn't enough room. As I said previously, getting the turbo off and out of a PQ35 platform with a BKD and 4-M is an uttereley appalling job. We did an A3 a few months ago and it was a sketch of epic proportions. The thing that really upset us was we had just done the clutch and only found the turbo was clogged on the post job road test, some choice expletives were uttered. With how difficult the turbo is to remove, I strongly recommend you take it to a turbo specialist and have it rebuilt as the BKD blower suffers from bearing wear as well, you would be gutted to have to take it out again for the sake of a £250 professional rebuild. I am not exaggerating when I say it could be quicker to take the box out to do the turbo on this model.

[davik3]

my 55 plate 2.0 tdi has this kind of problem it looses all power but if I turn the ignition of and then on it has full power straight away again it logs no fault and I have been told this is probably an overboost valve problem

[Crasher]

It is obviously going into limp mode so it will be logging a code but what you are using to read it is OBDII only and it will not be an OBDII specific code so you need a proper code read carrying out.

[d4n93rm0u53]

Well guys I'm back with an update, and this isn't a bad one...

It's fair to say that I'm quite stubborn, and a Yorkshire man which means I don't like to spend money. I had always been determined to resolve this issue of myself, or at least ensure the eventual resolution was correctly identified in the first instance. All of which means I've delayed having the turbo removed, in the meantime I have used the car for limited distance journeys. Occasionally I've popped the bonnet and scratched my head, for sure I've poked and prodded at things too (as you do).

I couldn't get my head around why the turbo had suddenly switched from under to over-boost, either one of these symptoms alone I could understand. I've never had any issues in the last 45k and so it seemed unlikely that things would suddenly get completely stuck at both extremes.

On Friday I took the day off work and got my Golf back up on the ramps to re-investigate that turbo actuator.

I'm quite familiar with this mechanism now, albeit through touch alone, you can't see much from below or above ...this time around it was immediately obvious that something had changed.

The arm had become separated from the actuator at the point of adjustment! I'm guessing the lock nut had been loose for sometime, the vane control arm was now just flopping around. It was a swine to re-thread due to the tight access, also my tongue was very numb after holding the vacuum (necessary to retract the actuator).

After a quick test drive I was sporting quite the cheesy grin, problem solved!!

In other news, that awful rattle?! Off-side rear break back-plate, its being welded up Monday morning.

[joca]

Great news and better perseverance. [emoji4]
Thanks for keeping up with updates to the thread.

[Crasher]

Never seen that happen.

[yourPAL]

Hi. This is my first post. Was searching for a solution to my VW Golf 1.9 TDI limp mode. Went to a local garage and did the turbo clean. Limp mode and warning light gone. Hoping this will be a lasting solution. I was advised to take the car for good runs from time to time and to rev it up a bit (which will then destroy the fuel consumption, the reason I bought a diesel). I was also advised to use an additive.
Any further advice?

[Doctle Odd]

Hi. This is my first post. Was searching for a solution to my VW Golf 1.9 TDI limp mode. Went to a local garage and did the turbo clean. Limp mode and warning light gone. Hoping this will be a lasting solution. I was advised to take the car for good runs from time to time and to rev it up a bit (which will then destroy the fuel consumption, the reason I bought a diesel). I was also advised to use an additive.
Any further advice?


My advice (for what it's worth) is dont use additives. A good 20 minute run with the revs up once a month does help the DPF if you have one. It would take pretty poor driving to return lower than mid 40's MPG.

[quattrokid]

This may be worth a look, I did it on m Mk4 Golf and had no issues for a good few years thereafter, in your situation and in my opinion, you have little to lose, I have no experience of any other cleaners and no links to this company but at least it is a product meant for the job.

[niall campbell]

With diesels you get a lot more exhaust gases than a petrol engine.

That means once a week you need to decoke the exhaust.

Put the car in 2nd gear & keep it there, blast the engine until the revs are just under the red and travel a couple of hundred yards along the road .

Its called an Italian decoke and from tractors to lorrys to cars, it works wonders.

Just make sure that your timing belt isn't due

It will restore power and mpg

[yourPAL]

Thanks for that input. My golf has 140k miles. Is the timing belt due every 80k?

[yourPAL]

After I had the turbo cleaned, the car gained quite a bit of power. I drove it about 2 weeks later (my wife drives it daily) and felt it had lost some of the pull-off power again. Now it has just gone into limp mode again. Could this have been that the cleaning liquid didn't get to all the dirt and more has become stuck? What should I do next? Advice please!

Also, how do I find out which turbo is on the VW?

[Crasher]

The reason the problem has come back is that chemical cleaning does not work....

[niall campbell]

Does the car go into limp mode when the turbo kicks in, or about to kick in ?

Checking the nut that you tightened before would be a good starting point

[yourPAL]

I haven't tested it thoroughly as I don't want to take risks. What I can say is that at 3000-4000 rpm in 1st and 2nd it doesn't cut out and the turbo is already working (I haven't pushed more than that). The episode that caused it to cut out was on the highway at maybe 60-70 mph.
Besides having cut out, I feel in general at low speeds (for example pull off) the Golf has much less acceleration that right after the clean.

[yourPAL]

Was told today that the glow-plugs might not be working properly and therefore not burning the soot, and that will lead to dirt accumulating after the clean. Any input on that?

[quattrokid]

That's an interesting one, I was told by a mechanic I like and trust that the ECU controls the Glow plugs on modern engines and they come on much more often that they used to, to help with burning unburnt fuel etc. I ran this past someone else though who said it was a load of rubbish, they just do what they always did in fact they are barely needed nowadays even for starting, go figure!
I am interested now if anyone can confirm for definite.
I used to be on Club TDI a lot a few years ago and loads of guys on there removed and manually split and cleaned their Turbos. The belief was that this was the best and only way to do it right. I know a mechanic who did this to his own car and it didn't work, a lot of work for nothing! They do start to soot up again, immediately you start the engine but normally it takes a while for enough soot to build up to make a difference, unless of course it wasn't really cleaned properly and that's impossible to tell unless you remove and strip it. Sorry thins isn't much help, free bump anyway!

[DMitch16]

The modern glow plugs now contain a pressure transducer called a “Glow Combustion Sensor” or GCS. This has the ability to read the pressure in the combustion chamber and make adjustments to the temperature of the burn so that maximum burn efficiency is achieved, less soot produced (helpful for the DPF cars as the DPF soot load is reduced) and better power / mpg. It is the equivalent of having several oxygen sensors. These glow plugs can cycle on and off in milliseconds controlling the heat of the combustion. Anyone who says they are only for cold starting should bring themselves into the 21st century!

Most cleaning solutions do not reach the parts that are really important in a VNT unit notably the rotator ring controlling the vane angle. This ring can still be stiff or sticking after cleaning and therefore a proper split clean necessary to ensure all deposits, rust, corrosion and soot are completely removed to prolong the correct working order of the turbo.

[yourPAL]

Thanks for that info. After reading a lot on the net to try to understand the problem, I am considering doing a system clean with Archoil AR6400-D Pro PEA Concentrate Diesel Cleaner as the Golf also doesn't idle perfectly smoth.

[Crasher]

Assuming your car is a Golf 5 1.9 TDI with a BXE engine from around 2004>2008 then it has active glow plug monitoring BUT does not have pressure sensing glow plugs, they have really only come in with the newer EU6+ engines and a very few select engines since 2009 but are still not used extensively. They are going to be fun when they start going wrong, instead of costing £21, they are £90 each! If you have a faulty glow plug or two, then this will come up as a fault code and all four often brings the emissions warning light on. No amount of snake oil chemical cleaners are going to fix your car.

[DMitch16]

£21? Got my genuine NGK CZ 7v plugs for less than £15 each. Presumably the ECU on EU6+ cars will have software to accomodate the newer GCS plugs which means replacement with non GCS ones very difficult, as expensive or nigh on impossible? I remember when Champion single spark plugs on a petrol car were £1.25 each but now apparently 'the new technology in them' means that standard replacement spark plugs are 10x the price now!! Seems like glow plug technology is heading the same way.

[yourPAL]

Thanks for everyone's input. Not being a mechanic, it's very difficult to get free advice so it's appreciated (even when there are contradicting opinions).

I'm currently getting 37 mpg in short city drives (car is basically to take the kids to school). Could this be related to the fuel system being dirty (that, together with the uneven engine idling is the reason I am thinking of using Archoil AR6400-D Pro PEA Concentrate Diesel Cleaner

[Crasher]

£21? Got my genuine NGK CZ 7v plugs for less than £15 each

The genuine VW price is £21.31 including VAT but of course you can buy them for less, they are only £10.60 from GSF for the approved Bosch or Beru; NGK are only approved for certain applications on the Golf 5 such as the 170PS BMN engine. Many cars have the option in the coding to alter the glow plug characteristics.