[T6_measured] 4motion Abnormality And Subsequent Failure

[mmi]

Reference documents:

VW Self Study Programme SSP 561 –The T6 2016, which in chapter Power transmission (p.26) for details on 4Motion control logic refers to:​

VW Self Study Programme 414 – 4MOTION with 4WD coupling generation IV. The document can be read and downloaded at SSP 414​

​

Spesifics about 5th generation Haldex clutch from page 20 onwards in​

VW Self Study Programme 515 – The Golf 2013 Running Gear and Four-wheel Drive Concept. ---> SSP 515​

T6’s used in the evaluation

(1) MY16 T6 panel van T32 16” chassis LHD LWB Engine CXFA (04L 906 056 KF rev 3809) EU6 110kW/150PS DSG (SW:5220) 4Motion (SW:7620)​

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(2) MY18 T6 panel van T30 16” chassis LHD LWB Engine CXHA (04L 906 056 KE rev 3772) EU6 110kW/150PS DSG (SW:5301) 4Motion (SW:7620)​

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(3) MY17 T6 panel van T30 17” chassis LHD LWB Engine CXEB (04L 906 056 KN rev 3776) EU6 150kW/204PS DSG (SW:5302) 4Motion (SW:7620)​

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(4) MY18 T6 panel van T32 17” chassis LHD LWB Engine CXEB (04L 906 056 KN rev 3776) EU6 150kW/204PS DSG 4 (SW:5302) Motion (SW:7620)​

​

During past two years in the van (1) three coupling pumps (V181) and two complete Haldex-clutches were “evaluated”.​

Some clarifications about terms used later.

Terms clutch, coupling, Haldex-clutch, etc, all refer to the same coupling unit used in T6 4Motion models.​

​

The term “Haldex-clutch degree of blockage” comes from VCDS measuring values, similar term is used also in VW garage testers. Value 0% means the coupling is open and no torque is transferred to/from rear axle. Value 100% means that clamping pressure at the clutch is at maximum and torque up to 2400 Nm can be transferred to/from rear axle.​

Introduction – How 4Motion works in different driving situations


Pulling away or accelerating - measurement

The measurement graphed below was just to measure actual control range mentioned above. General idea is that clutch clamping pressure/force is high at slow speeds and gradually decreases as speed increases (when accelerating).​

Explanations.​

• Time scale 20 seconds/division, full picture 200 sec.
• Red line - vehicle speed. Scale 0-100 km/h.
• Green line - Haldex-clutch degree of blockage. Scale 0% in the middle, full scale 50% (just to better show low values).
• Yellow line - measured speed difference between front and rear axle. Scale 0-5 km/h, so each horizontal line equals to 0.5km/h. Noisy curve at the bottom.
• Circle C – At steady cruising speed (90-100km/h), very low coupling, degree of blockage, 1-3%.
• Circle B – Note a speed delta between front and rear as vehicle is mainly front wheel driven running at steady speed - the rear wheels are almost just free rolling.
• Circle A – At full throttle very tight “preemptive” coupling, the coupling does not allow speed difference between front and rear axles (yellow line at the bottom).
• On the left at time stamp 25-75 sec, speed (red) from 0 km/h to 80 km/h, starting at first notch on the left. – normal, easy pull away - preventive “reasonable level” of coupling (green).
• Before full throttle pull away – quite hard braking to stand still at time stamp 110-120 sec, some slippage (delta spike (yellow)).

From the graph/data above only theportion of full throttle pull away graphed to depict degree of blockage (Haldex-clutch coupling) vs. vehicle speed in the graph below.​

​

Proves the general idea that clutch clamping pressure/force is high at slow speeds and gradually decreases as speed increases.​

​

Note that in the above the blockage is the absolute maximum blockage as engine is using low gears to gain more torque at wheels through gearing ratio. Thus the maximums above are from gears 1-4.​

​

On higher gears degree of blockage needed is less. For example on 6th and 7th gears at speed of 80 km/h max blockage achieved is about 10% (about half of the absolute maximum). On the 5th gear slightly more 13%, etc.​

Fast driving - measurement

The measurements also verified the behavior and control range at “fast driving” – degree of blockage/coupling from 0% (engine braking) up to predetermined value (as in the graph above). An example at circle “C” in the first graph.​

Braking - measurement

Verified – disengages with slightest touch of brake. Except at standstill, then the coupling is prepressurized thus giving no-slip set off. Degree of blockage/coupling observed is about 12% at standstill when foot on brake, idling, gear D1. Goes immediately high up when throttle is applied.​

Stopping - measurement

Actually means engine braking (coasting function not yet verified). The clutch is disengaged - degree of blockage/coupling is 0%.​

Good news. I fully agree with logic presented in the documentation and also verified the stated functionality on vans with 150kW/204PS engine on all DSG gears 1-7. Test vans (3) and (4).

Not so good news is that the above seems to be true only on DSG gears 1-4 on vans equipped with 110kW/150PS engine. Test vans (1) and (2).

In the table below detailed values for “Degree of blockage” on these vans.​

How to read.​

​

Pick a line. For example line 80 km/h. R​

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On the 5th gear​

• at full throttle degree of blockage is 7.5% - which is almost as expected.
• no throttle = engine braking, degree of blockage is 0% - rear wheels are freely rolling which is as expected – ok.

On the 6th gear​

• at full throttle degree of blockage is 0% - which means the clutch is disengaged – no torque to rear axle, van is front wheel driven.
• no throttle = engine braking, degree of blockage is 0% - rear wheels are freely rolling which is as expected.

On the 7th gear​

• at full throttle degree of blockage is 8.3% - which means the clutch is engaged – actually at the maximum for that speed, maximum torque to rear axle.
• no throttle = engine braking, degree of blockage is still 8.3% - which is not as expected – the clutch is always engaged at the maximum coupling for that speed, maximum torque to/from rear axle.

A sample from a 110kW/150PS DSG van (1) graphed: Symbology as in the first graph. Gears used marked in the picture. Note and compare speed delta (yellow at the bottom) with the first picture.


Manual gearbox

No, I can't tell whether the same is true with manual gearbox. I haven't had a chance to hook up to one, yet. I am definitely interested to hear if things are any different....​

To be continued...

 

[mmi]

My story

I noticed occasional strange behavior in my van (1). Sometimes in the turn the van suddenly made the turn more sharply – a kind of jump inwards of the curve- On left turn, steeper left. On right turn, steeper right. My first thought was there had to be oil/wet on the road and the car slipped and then regained the traction. More history and my early speculations in Engine Power Loss​

At 13350 km – October 2016.

After my persistent complaints of the behavior the garage took the van in for inspection, wheel alignment was checked and eventually even oil was drained from Haldex-clutch. The technician had saved it for me and it was easy to agree that it shouldn't be black and smell like burned clutch at that point yet. Specified oil change interval is 60000km.​

At 15210 km – December 2016

Engine software update.

I had long planned to purchase a VCDS, so went ahead and ordered one a few weeks later. Out of curiosity hooked it into 4Motion/Haldex control unit. Of course, it took a while to get some understanding how to interpret the values.​

At 18400 km – January 2017

Pretty soon I came to conclusion that on 6th gear 4Motion Haldex-clutch/coupling disconnects at certain speeds. As I told about my observation the technician wanted to hook VW garage tester and have the same run to collect data for the factory. The test point was to drive steady 80 km/h, DSG on 7th gear and switch to 6th gear, back and forth, at full/some/no throttle.​

The results: 4motion is disabled on 6th, on 7th "locked on" to a constant value of 8.3%. So the VW got both VCDS and their own tester data and some paperwork to start working on.​

Because I wasn’t comfortable at all having 4Motion van, which is not 4-wheel driven on gear 6, the dealer offered another van for comparison. Un/fortunately the van was not exactly the same. Mine was 150PS but the demonstrator was 204PS. But, according to all available documentation their powertrain is the same. That's what also VCDS showed, identical DSG though different software, fully identical 4Motion unit. So it was good to go for a comparison.​

To my amazement the behavior of this 204PS DSG 4Motion was exactly as documented - including gears D5-D7 – foot off the throttle releases the coupling, applying throttle “tightens” the coupling, more I push, the tighter the coupling.​

I handed over the data from this van (2) for comparisons stating that this is as it is advertised to work and the van (1) is not working as specified.​

At 32420 km – November 23rd, 2017

As the end warranty was soon to expire (only 2 years up here), I had reminded about this not yet resolved misbehavior of 4Motion. The garage accepted my request to have another look at my complaints and drain again the oil from Haldex-clutch when the van would be in for other repairs - Injector failure​

The oil below. It is quite difficult to get a good picture of impurities in oil. In the picture the crater is a wave after drop of oil. The shiny spots are presumably metallic dust, which comes here into view thanks to flashlight. Also worth noting the grayish shiny component of oil in and around the crater. The oil looked like grinding paste (19070 km on that oil).

The garage had discovered a service bulletin related to non-working 4Motion. In short: Coupling pumps will be replaced if two conditions are met: 1) Customer reports of non-working 4Motion and 2) Serial number of the pump is before certain date. Both conditions were met so the pump was replaced.​

In the picture the old pump and it’s oil inlet. Presumably covered with metallic dust. Serial number in the circle on the sticker.


​

At 32465 km – November 23, 2017

1 Fault Found:
16668 - Pump for Haldex Clutch
C1112 07 [008] - Mechanical Failure
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 1
Fault Frequency: 1
Reset counter: 200
Mileage: 32465 km
Date: 2017.11.23
Time: 15:56:32

So, it was the first time the Haldex-clutch threw a fault code – only 45 km after replacement of the pump. Next morning the van was hooked into VW tester again for fault diagnosis. No more was discovered than the VCDS code above.​

Unfortunately T6 (nor T5) won't indicate on the dash any way the loss of 4Motion . It just disconnects itself - zero torque to rear wheels. Interesting, or confusing, thing is that switching ignition off, and switching ignition on resets the 4Motion and it probably will be just fine till it fails next time.​

Anyways, the total failure above was the culmination point. The garage was instructed/allowed to replace the total package, clutch, pump, controller. So I and the technician were hopeful that annoying behavior would go away (personally I was suspecting/hoping the controller to be the culprit).​

At 33000 km – December, 2017.

The complete Haldex-unit arrived and was replaced. After the fault the van interestingly didn't report any failures in 4 weeks before replacement. So, without the metallic oil and blocked pump the procedure might have been just to reset the fault.​

Unfortunately I couldn’t have the old clutch – it definitely would have been interesting to disassemble it. Nothing obvious because the friction plates are in there.
​

Unfortunately no change in 4Motion behavior – still no torque on 6th gear at 80 km/h, locked on 7th gear. I wasn’t happy at all.

Up to this point my case was “valid” as the data from vans (1) and (3) were drastically different, so I was told the VW is working on the case.
The garage was instructed to find a “more” similar van to verify if the same zero/locked torque to rear axle on gears 5-7 is the same. The van (2) was available and I did a run with the technician unfortunately with the same disappointing results.​

In summary

During the challenge all kind of explanations have been proposed and were analyzed and discussed:

• the van is front wheel driven at normal travelling speeds,
• vibration damping,
• fuel economy,
• can’t be wrong because it is such a basic functionality,
• the 4Motion logic takes all possible factors into account so it is impossible to analyze it by doing such a simple test (driving steadily at 80km/h), etc, etc.

So, the tests and the graphs above were just to convince myself and the garage how the 4Motion really should work. As the graphs from a real van show that the coupling has no discontinuities. Coupling starts at full lock when at low gear and full torque from engine. As speed increases and gearing ratio reduces torque at the clutch, also degree of coupling decreases. When foot is off the throttle, coupling is fully disengaged. Normal driving – coupling is varying dynamically between 0 and some predefined maximum.

Just a note that all these examples were driven so that the ESP is not kicking in, no extreme maneuvering, just duplicating the boring driving I do most of the time, steady 80-85 km/h.
​

To be continued...

 

[mmi]

January 2018 - today

Based on test drives done in December the final statement from upper levels was that there is nothing wrong because identical vehicles have identical characteristics and no fault codes are present. The failed clutch is just an isolated case which they happily had replaced under warranty. The end of that discussion.

My plan was to keep the van for long time so I expressed to the dealer my great dissatisfaction of only partially working 4Motion in my van especially as there is also a fully functional variant available. Eventually we reached an agreement and replacement van (4) was ordered and delivered a few weeks ago – and verified to have 4Motion that works as advertised. So I’m off the hook now.

At the moment my biggest fear is that the baseline of soon becoming software update is the software from 110kW/150PS engines. Be assured that I shall test the update on dealer’s demonstrator before accepting it to be injected into my new one.​

My concluding statement

is that there is a significant design flaw in T6 4Motion vans equipped with 110kW/150PS engine types CXFA or CXHA with DSG gearbox. The design flaw creates “blind spots” where the van is only front wheel driven (red in the table). In other areas (orange) under normal driving and DSG gearing conditions the 4Motion is locked not allowing any speed difference between front and rear axles.

This design flaw does not exist on T6 4Motion vans equipped with 150kW/204PS engine type CXEB with DSG gearbox.​

My surmise

is that the design flaw above will lead to unpreventable failure of 4Motion clutch/coupling by prematurely wearing out friction plates and eventually actual clutch plates. The root cause of this excessive wear is tight, but not tight enough, coupling which tries to keep front and rear axles rotating at same speed but the torque from the wheels (due to turns and mass of vehicle) overcomes the clamping force of coupling thus forcing it to slip, and eventually turning the clutch to metallic dust. At terminal phase due to wear and tear the clutch reaches limits of its calibration and/or the inlet of hydraulic pump gets blocked. Eventually also a fault code is triggered.

The van (1) was driven mostly empty but unfortunately most of the time in speed bracket 80-85 km/h on 7th gear. About one third was on snowy and icy roads so I’m assuming that the wear and tear of the clutch wasn’t even as severe as it could have been. My speculation is currently supported only by this isolated case of van (1).
​

I understand the seriousness of my statement and I definitely would be more than happy to hear a logical explanation why 4Motion implementations are so different in vans that look the same.

I also understand that my sample size is not big so either I'm the most unlucky with 150PS variants and the most lucky one with 204PS variants or just maybe "Volkswagen, we have a problem".

Dear Forum Members, please comments, speculations, ideas, objections...

 

[DaveyB]

January 2018 - today

Based on test drives done in December the final statement from upper levels was that there is nothing wrong because identical vehicles have identical characteristics and no fault codes are present. The failed clutch is just an isolated case which they happily had replaced under warranty. The end of that discussion.

My plan was to keep the van for long time so I expressed to the dealer my great dissatisfaction of only partially working 4Motion in my van especially as there is also a fully functional variant available. Eventually we reached an agreement and replacement van (4) was ordered and delivered a few weeks ago – and verified to have 4Motion that works as advertised. So I’m off the hook now.

At the moment my biggest fear is that the baseline of soon becoming software update is the software from 110kW/150PS engines. Be assured that I shall test the update on dealer’s demonstrator before accepting it to be injected into my new one.​

My concluding statement

is that there is a significant design flaw in T6 4Motion vans equipped with 110kW/150PS engine types CXFA or CXHA with DSG gearbox. The design flaw creates “blind spots” where the van is only front wheel driven (red in the table). In other areas (orange) under normal driving and DSG gearing conditions the 4Motion is locked not allowing any speed difference between front and rear axles.

This design flaw does not exist on T6 4Motion vans equipped with 150kW/204PS engine type CXEB with DSG gearbox.​

My surmise

is that the design flaw above will lead to unpreventable failure of 4Motion clutch/coupling by prematurely wearing out friction plates and eventually actual clutch plates. The root cause of this excessive wear is tight, but not tight enough, coupling which tries to keep front and rear axles rotating at same speed but the torque from the wheels (due to turns and mass of vehicle) overcomes the clamping force of coupling thus forcing it to slip, and eventually turning the clutch to metallic dust. At terminal phase due to wear and tear the clutch reaches limits of its calibration and/or the inlet of hydraulic pump gets blocked. Eventually also a fault code is triggered.

The van (1) was driven mostly empty but unfortunately most of the time in speed bracket 80-85 km/h on 7th gear. About one third was on snowy and icy roads so I’m assuming that the wear and tear of the clutch wasn’t even as severe as it could have been. My speculation is currently supported only by this isolated case of van (1).
​

I understand the seriousness of my statement and I definitely would be more than happy to hear a logical explanation why 4Motion implementations are so different in vans that look the same.

I also understand that my sample size is not big so either I'm the most unlucky with 150PS variants and the most lucky one with 204PS variants or just maybe "Volkswagen, we have a problem".

Dear Forum Members, please comments, speculations, ideas, objections...

Wow, that is hell of a bit of research. Well done. Be interesting what if anything VW does about it for other 4 motion drivers. My guess is that they will ignore it, keep quiet, and then charge people a bloody fortune to replace failed components.
Or is that just me being sceptical?

 

[Pauly]

VWs motto #Plausible deniability

 

[Loz]

Two things spring to mind;
Fuel economy, have they rigged the 110/150 to work like this to improve economy by reducing drag?
Secondly, reinforcing the need to have trye pressures and tread depth the same all round.

 

[t0mb0]

Top quality research!

I wanted 4motion for our 150bhp DSG but it wasn’t actually an option at the time (2016 UK) unless you forked out for a 204bhp so I didn’t get it.

I wonder if this means 150bhp DSG 4motion vans are relatively rare and therefore haven’t had the same level of scrutiny as the 204bhp?

 

[Dieseldonkey]

Fascinating reading there @mmi. Atleast your dealer seemed receptive to the issue. I think it wouldn't just be a Haldex clutch that would be loosening, if you dropped those findings on the desk of a service manager in many a UK dealerships.

I wonder if it was a bit tricky getting the combination of a T6's weight, 150PS, diesel DSG and 4 motion through emission tests. And if said test happened to involve long periods of time in the gear in question. Sacrificing vehicle stability to meet an emission threshold perhaps. Mmmhm.

 

[alter]

..... I wanted so much a 4motion ... on my 150 hp manual .... but after seeing this I'm less worried ....... the VW does not stop to amaze WITH THE SCAMS !!

 

[toonaroon]

I am so glad there are people like mmi that are willing to go that extra mile when it comes to technical issues, however I am feeling more and more as though VW just like to see the Deutsche Mark's roll in...

 

[mmi]

Thanks all, I appreciate.
For anyone interested in technical details and principles - document "SSP 515 The Golf 2013 Running Gear and Four-wheel Drive Concept" pp. 20-27 describes some technical details of the 5th generation four-wheel drive clutch - the same generation clutch as used also in T6.
Available here --> SSP 515

 

[mmi]

The plot thickens -

vw Transporter P20EE 00 [232] - Efficiency too Low

Hi Trying to help a frien with this error, is this just a bad NOX sensor ? Thanks for any help Regards Rune VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64 VCDS Version: 21.3.0.0 (x64) HEX-V2 CB: 0.4543.4 Data version: 20210226 DS325.0 www.Ross-Tech.com VIN...

forums.ross-tech.com

The van is identical to reference T6 (2) (in 1st post) - engine/software, transmission and Haldex-clutch.
The van is MY17, however the Haldex-clutch (controller) has build date of 18-June-2019 - Serial number: HA1-00018.06.19

 

[Rids]

I’d like to check this out on my 6.1, it’s a 150, manual, 4motion. Interestingly I couldn’t order a 150/DSG/4Motion… not an available configuration in Sept 20.
Anyhow I have VCDS but am pretty much a novice with it… so if you’d like to pm me some clues to set it up I’ll give it a go.

 

[mmi]

I’d like to check this out on my 6.1, it’s a 150, manual, 4motion. Interestingly I couldn’t order a 150/DSG/4Motion… not an available configuration in Sept 20.
Anyhow I have VCDS but am pretty much a novice with it… so if you’d like to pm me some clues to set it up I’ll give it a go.

Excellent! Below a proposal how-to:

Meanwhile, could you please post here or PM me the VCDS Auto-Scan - as it has turned out on T6 and on T6.1 there are numerous software variants on engines.

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► VCDS ► Select Control Module ► 22-AWD ► Adv. Meas. Values

► Tick "Group UDS requests" - by 7.

► Tick either the following parameters individually OR use the attached file (see further down)​

IDE00019 Voltage terminal 30​

IDE00920 Front left wheel speed​

IDE00921 Front right wheel speed​

IDE00922 Left rear wheel speed​

IDE00923 Right rear wheel speed​

IDE01617 Clutch temperature​

IDE04502-MAS04730 Haldex clutch status-Degree of blockage​

IDE05609 Cooling fin temperature​

IDE05707 Haldex clutch pump current​

IDE05708 Haldex clutch pump PWM signal​

IDE05710 Haldex clutch pump voltage​

IDE06111 Axle speed deltas​

► Log ►... ► Start​

► Stop VCDS logging etc.
► The logfile (.CSV) will be in folder C:\Toss-TechVCDS\Logs

---

Basically for the analysis is needed to run through all the gears:

(1) starting at about 1100 RPM (or whatever low RPM is convenient)​

(2) click on the Marker and make a note of the gear in use​

(3) accelerate up to 3000 RPM at moderate throttle - certainly can do at full throttle but things happen then too fast especially on lower gears​

(4) foot off the throttle and let it slow down by engine braking (down to about 1100 RPM)​

(5) click on the Marker and make a note of gear used​

​

(6) speed up and select next higher gear --- go to (1)​

​

Using the Marker button helps a bit to keep track which gear was in use as the 22-AWD doesn't keep track of it.​

Well, probably not a good idea to go up to 3000 RPM on higher gears

More than happy to look into the collected data, so please post the logfile(s).

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Attached a preformatted setup file (of the above parameters) for VCDS recording. Just remove the PDF-extension (was needed because Forum doesn't accept u22-files).

The file can be loaded into VCDS by selecting it from top left corner in Adv.Meas.Values)

 

[mmi]

Got an opportunity to carry out some experiments on

T6.1 CXFA (110kW/150PS) manual 4Motion.​

Basically for the analysis is needed to run through all the gears:
(1) starting at about 1100 RPM
(2) click on the Marker and make a note of the gear in use
(3) accelerate up to 3000 RPM at moderate throttle - certainly can do at full throttle but things happen then too fast :laugh: especially on lower gears
(4) foot off the throttle and let it slow down by engine braking (down to about 1100 RPM)

Unfortunately it seems to be the same old story


Please note the scalings for the illustration:

"IDE04502-MAS04730 - Haldex clutch: status-Degree of blockage" for the illustration (here actual value x 10).​

"IDE06111 - Axle speed deltas [km/h]" (here actual value x 20).​

As earlier in this thread, a concern is that on gear 6 Haldex clutch never releases below 90 km/h - not even foot off the throttle (=the declining slope in the picture).

---

EDIT: Full set of measurements on this one:

[T6_measured] A Comparison of 4Motion traction modes

4Motion Adaptation channel - MAS06098-Acoustic measure wiring logic STANDARD / INCREASED TRACTION / REDUCED NOISES T6/T6.1 Haldex clutch has an adaptation channel which presumably changes clutch clamping behaviour. The channel can be tweaked with various tools. Conditions for the measurements...

www.t6forum.com