We've had our Superb 63 plate 2.0TDI, 4x4, DSG for a couple of months now. The DSG box seems to split opinion but I quite like it and, so far, it's basically behaving as I'd expect. The only exception is when I enable cruise control at motorway speeds.

 

In normal driving mode, the DSG box works quickly to put the car into the highest possible gear. At low speeds (30-50mph) the cruise control and DSG box do much the same, generally trying to be in at least 5th if not 6th gear. However, roll up to the ~70mph speed range and it starts to behave quite differently:

 

1. If driving on an uphill section of road the car will attempt to be in 6th gear unless the gradient demands a downshift. All good, as expected.

2. If on a flat road, the car will drop to 5th and stick there (humming away)

3. On any sort of downhill gradient (even slight), the car will drop down to 4th and rev away at 3500rpm (making a proper racket in the process)

 

I've read about the DSG and cruise control working together to implement engine breaking when possible but the gentle downhill gradients I am talking about still require some throttle so the engine is delivering power and running at 3500rpm. Also, this doesn't explain 5th gear on flat roads.

 

What's weirder is that if you adjust the cruise control down to a lower speed on a flat or downhill section of road, as you drop somewhere below 50mph it starts to behave a bit more normally and puts itself back into 6th gear.

 

Lastly, the day I bought the car I did big drive on the motorway and used cruise control the whole way, I don't recall it ever being in anything other than 6th gear. The only thing that has changed since then is that I had the gearbox oil changed at the dealer. I'm sure the DSG box is okay (it works great outside of cruise control) but perhaps I have picked up a software update that has modified the Cruise/DSG behaviour?

 

Sorry for the mammoth post but it's a complicated thing to fully describe. Curious to hear any thoughts.

 

Ta,

 

ip

 

 

 

 

You do not pick up Software Updates they are done by what should be Qualified Technicians, so ask where the Oil / Filter change was done what they did to your DSG.

Thanks. I do intend to ask the dealer if a software update was applied as part of the DSG service.

 

Meantime, I'm keen to hear from other owners if the DSG/Cruise behaviour I described seems normal after all.

 

cheers,

 

ip

Edited 4 June, 20179 yr by iperry

Wee bump on this. Can anyone else comment on their car's DSG behaviour when using Cruise at motorway speeds?

 

Ta,

 

ip

My 2012 Octavia vRS CR DSG is fine on the motorway when using cruise control.  However, I rarely use cruise control on UK motorways as there is usually too much traffic, but I have used it extensively in France.  The choice of gear seems no different whether or not I have cruise control engaged.

Sorry no other than odd behaviour and something not right.

 

Can you say which Dealership you were at for the Gearbox Oil & Filter change of the DSG?

I used, western in edinburgh. I keep calling and being told they'll phone back. Useless.

 

ip

Indeed they can be.

If you are in the Dundee or Perth area at any point see if a Tech at Skoda Specialist Cars John Clark group can take it for a road test. 

They are only a mile of so at Dundee or Perth from roads suitable to do Road Tests and see what is up if anything.

Check spare wheel compartment for new sticker - check forum for more info about software update.

 

Havent experienced such problem but my car done only 19k

?

What software update service campaign is there on the 6 speed wet clutch DSG?

http://master.skoda-auto.com/mini-apps/recall-actions 

Does not always show Service Campaigns or recalls let alone just 'Software Updates'.

 

............................

OT,

but just for information, as Skoda, VW, Audi, SEAT are a bit shy to mention in public.... Like on Websites or press releases.

(There are 2 on the DQ200 7 Speed Twin dry clutch if anyone is interested.)

'34F7' 2009-2013 or later would have sticker in the boot if done.

'34H5' 2013-2015 started late 2016 would have a sticker in the boot.

Thanks to all.

 

My car is only on 19k too and, as I say, the DSG works great when not in Cruise. The main reason I thought of the software update was that I'd read a few forum posts about inclusion of engine braking in certain software updates. That said, dropping to 4th on a gentle downhill slope at 70mph doesn't seem like engine braking to me.

 

Cheers,

 

ip

 

 

So, here's a VW golf with pretty much the same issue:

 

http://forums.tdiclub.com/showthread.php?t=309442

 

If you follow the link on the second page to the video, the poster reckons he fixed the issue by moving to tyres with a larger sidewall. I'm on the standard 18" rims that came with the car with recommended tyre size. That said, I have swapped the front tyres from contis to nokians since buying the car. Hard to believe that could have this effect though.

 

Cheers,

 

ip

 

 

The cruise control system is using the wheel speed sensors to determine the vehicle speed.

 

Depending on wear levels and the variation in dimensions between tyre brands/models, it's just possible that the variation in speed signals from the different wheels is confusing the ecu when in cruise. IMO it shouldn't be an issue, but it's just possible that it's an edge case the software developers didn't account for when developing the cruise control routines.

 

If you have VCDS or know someone who has it, it might be interesting to log individual wheel speeds while on a test drive to see if it shows up anything.

6 hours ago, iperry said:

My car is only on 19k [...]

?!?!? Then why oil change in DSG ?? It should be done after 40k.

 

And I was referring to ENGINE software update.

Edited 6 June, 20178 yr by jafo

There could be something in this about the tyres circumferences confusing the electronics as is being suggested, but it does sound unlikely although being a 4wd it will be checking for large rotational differences and trying to compensate for them. Its a quick and simple thing to do to swap the wheels around on the car to see if it improves and to double check the sizes and the pressures are to spec.

jafo, Sorry my bad.

Is this the possible answer, have WESTERN done the fix and not informed the OP. 

 

& as you are asking, why the DSG Oil & Filter change, has the car covered only 19,000 miles?

Edited 6 June, 20178 yr by Awayoffski

I've a 2011 mk2 SuperB and use the cruise control extensively on the M1. I've had the car for 8-9 months and done nearly 12k miles in that time and I've never seen behaviour like you're describing.

 

I've a very different engine but I can't recall it ever changing down at ~70 in that time for engine braking purposes. Off the top of my head, it's had the DSG oil changed 3 times in its lifetime.

 

I also have 4wd and I'm not sure swapping wheels front to back is recommended but I'm no expert. This does sound like it would be worth performing a DSG reset though. I believe the process is documented on this forum...

 

Cheers,

Steve

Thanks for all the responses. Updates:

 

1. Spoke to Western, they are adamant that nothing other than oil and filter change were carried out. No sticker in wheel well and car still shows up on the Skoda list as being affected by the recall. Western did the work over 5 weeks back so register should have updated by now if fix had been applied.

 

2. As to why I did the DSG oil change at 18k miles; Basically the previous owner did a lot of short journeys (hence on 17k on a 3.5 year old car when I bought it). Advice from various forums and a VW mechanic was that an early oil change would be a good idea.

 

3. Added a couple of PSI to the front tyres (those I'd replaced since buying the car) to ensure there was no issue with circumference. Even did quick measure of circumference vs the spare. Bang on the same.

 

4. Performed a DSG reset (ignition with accelerated depressed...). No change.

 

Checked my warranty and (predictably) it won't shell out for diagnostic checks so I'll need to shell out for the dealer to take a look I guess :(

 

Any other thoughts gratefully received.

 

Cheers,

 

ip

 

 

 

 

Avoid WESTERN,

ARNOLD CLARK,

PARKS,

EVANS HALSHAW,

 Maybe see HENRY's, INGRAM's or SKODA SPECIALIST CARS John Clark Group.

We have your engine / transmission combo and I use the cruise control with summer -18"- and winter tyres -16"- but I have never noticed the car hunting through the gear box. Even in the alps downhill it does not normally shift down to use the engine braking.

The idea brought up here about a wheel sensor problem should through up an immediate warning from yout TPMS that one tyre is deflating.

Thanks.

 

Many moons back I used Jack Walker Partnership in Edinburgh for an old VW I had. They're good and local and have full dealer diagnostics (apparently) so I might try them out. 

 

Cheers,

 

ip

Been a while but wanted to post an update on this.

 

Dealership and other local garages were all stumped. No fault codes or erroneous readings from sensors were thrown up. People started talking about mechatronic issues.

 

In the end I shelled out for the full VCDS system from Rosstech and started testing myself. Ultimately I took the car out for a run and logged all wheel speeds. Turned out that one wheel was reading 3%lower than the others. Swapping the wheels over (left to right) showed the 'slow' wheel followed the wheel in question. Careful measuring showed that the wheel did indeed have a 3% larger circumference than the others.

 

Counter intuitively, it was the most worn tyre on the car. Basically, it seems that Conti's are a bit larger for a given specified size than Nokian and Kumho which were the other tyres on the car.

 

Did some slightly scary stuff with tyre pressures to equalise the wheel sizes (three tyres high pressure and the conti very low) and the DSG/Cruise system started to work perfectly.

 

Replaced two tyres so the whole car now runs on Nokians and everything works as it should.

 

Some discussion with the support team at Rosstech suggested that the car uses wheel speed to determine if you are cornering. In CC mode, the car takes more notice of this info and shifts down (assuming you are cornering at high speed). This is why the CC/DSG issue only occurred at higher speeds.

 

Personally I'm surprised that such a small difference in tyre size could so easily 'confuse' the car but there you go. Hopefully all this info will be useful to someone else.

 

Cheers,

 

iep

 

 

 

 

 

Glad you sorted it but you should never have different types of wheels/tyres on the same axle - beside when you use spare. 

http://kouki.co.uk/utilities/visual-tyre-size-calculator 

3% is a very significant difference and if your TPMS was set and gave a warning, and you put on a 3% smaller spare and do not reset the TPMS then you should be getting further warnings.

3 hours ago, iperry said:

In the end I shelled out for the full VCDS system from Rosstech and started testing myself. Ultimately I took the car out for a run and logged all wheel speeds. Turned out that one wheel was reading 3%lower than the others. Swapping the wheels over (left to right) showed the 'slow' wheel followed the wheel in question. Careful measuring showed that the wheel did indeed have a 3% larger circumference than the others.

 

Counter intuitively, it was the most worn tyre on the car. Basically, it seems that Conti's are a bit larger for a given specified size than Nokian and Kumho which were the other tyres on the car.

 

Personally I'm surprised that such a small difference in tyre size could so easily 'confuse' the car but there you go. Hopefully all this info will be useful to someone else.

 

On 6/6/2017 at 14:09, chimaera said:

The cruise control system is using the wheel speed sensors to determine the vehicle speed.

 

Depending on wear levels and the variation in dimensions between tyre brands/models, it's just possible that the variation in speed signals from the different wheels is confusing the ecu when in cruise. IMO it shouldn't be an issue, but it's just possible that it's an edge case the software developers didn't account for when developing the cruise control routines.

 

If you have VCDS or know someone who has it, it might be interesting to log individual wheel speeds while on a test drive to see if it shows up anything.

 

The way the ABS computer measures wheel speed is it counts the number of turns the wheel makes per second and multiplies that by a nominal wheel circumference to calculate the speed.
 

At a fixed ground speed, a smaller wheel will have to turn more times than a larger one to keep up; likewise a larger wheel will have to turn fewer times. So your one larger tyre was making fewer rotations per second than the other three, and the difference was enough for the ABS computer to flag it as an issue.

 

I do wonder when these systems will start integrating GPS information so that these sort of cases can be handled more gracefully on the road.