# Pulsating S-tronic at low speed



## Razza (Nov 23, 2010)

Hi all,

My S-tronic (clutch) pulsates irritatingly when the car's crawling through traffic around idle RPM and just above, and in auto-selected 2nd gear. It results in a refined ride at this speed being extremely jerky and well, downright embaressing. Is this quite normal? Perhaps I should jerk my head in synchronisation so it won't look so bad? The car's done 40k miles and no error codes. Is the clutch/fluid/control electronics the issue?

Ta


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## brittan (May 18, 2007)

Sounds like the problem with the Mechatronic unit that some on here have reported which does not log any fault code.

Your dealer should be aware of this and the Audi repair is normally a replacement unit.

If you do a search it should provide some extra info.


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## brittan (May 18, 2007)

Some here:

search.php?keywords=Mechatronic+problem&terms=all&author=&fid[]=19&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search


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## powerplay (Feb 8, 2008)

Definitely the known Mechatronic controller problem.

Am guessing it's probably ok from cold but gets progressively worse as things warm up.

get it in for repair under warranty sharpish.


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## anbrian (Jun 14, 2009)

Hi -

It a faulty unit ???

I find and have found since the car was new found that at slow speed / stop start the ride was "jerky" however by putting the S tronic into Manual First Gear the jerky ride disappears. I observed that the S Tronic wanted to change up to 2nd / 3rd gear too soon.

Would you still consider this a fault ??


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## Razza (Nov 23, 2010)

Thanks all. Have been in to my local dealership and the service guy (customer facing non-techie) stated it might be normal - big engine - bite point blahdy blah. I will need to show their service ninja AKA 'master technician' what I mean and if he says it's normal, then I'll have yet another battle on my hands.

Pulling out is quite an ordeal now - you either floor it and ease off immediately or face the torment of jerking away from standstill. Not a nice sight however you wish to interpret that...

I would agree that by putting it into 1st manually it is much better BUT it's an S-tronic box, not a manual gear box! Why should I need to exercise my relatively weak wrists?!?!


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## wallstreet (Oct 19, 2009)

powerplay said:


> Definitely the known Mechatronic controller problem.
> 
> Am guessing it's probably ok from cold but gets progressively worse as things warm up.
> 
> get it in for repair under warranty sharpish.


+1 have to push Audi!! Talk to the master mechanic nit John boy jnr!

It's not norm.

It's supposed to be seamless not brain shaking!! any videos of you inside ?


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## Razza (Nov 23, 2010)

Wow. This is scaringly common and in most cases I'm seeing/feeling the same thing. Should I try resetting the control electronics as described here?

viewtopic.php?p=1494923#p1494923

I don't want to jeopardise my chances of having this fixed by Audi but once the problem has been reported to them and logged, it would appear (reading posts) that they honour the warranty.

If it's faulty, shouldn't the problems come back as soon as the mechatronic is warm again despite the reset? I'm thinking I might have confused it by driving newbie style. I have noticed that if you use the handbrake, whilst still in D with footbrake pressed, subsequent accelerating is very erratic. It 'remembered' the fact I had used the handbrake.... ooooooh


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## mikef4uk (Jan 15, 2006)

I had the same with my TTS, I could stop it by using S until they fixed it.

If they say 'it's normal Sir' find a tight parking spot and ask the service manager to park it...............


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## twocati (Dec 6, 2009)

My DSG was perfect but over time it became jerky and annoying during low speed parking or stop and go...I just assumed it was one of the quirks of the DSG..

My dealer diagnosed it within 3 minutes....the Mech.... unit was faulty. The car has been flawlwss since it was replaced...

To 100% diagnose if you have a problem , drive the car on an inclined road and stop. Release the brake - the car should hold steady with the revs increasing slightly as required to keep the car in it's postion. Next gently apply the gas - if the revs drop and the car shudders momentary you have a faulty Mech... unit. This is how the technician confirmed the Mech... unit was faulty as I was in the car with him....With a properly funtioning Mech... unit, the car smoothly accelerates with no drop in revs, hesitation or shuddering...

If you have this issue as decribed, dont let the dealer tell you this is normal.......


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## Razza (Nov 23, 2010)

Thanks. Will try that.

Should the car creep forward on a level surface? I get a forward surge after a second or so after releaseing the brake and not touching the accelerator pedal. I've even noticed that with the foot brake on, there's sometimes a random sharp drop in revs and a surge. Completely random so not easily repeatable in front of a technician.


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## twocati (Dec 6, 2009)

Razza said:


> Thanks. Will try that.
> 
> Should the car creep forward on a level surface? I get a forward surge after a second or so after releaseing the brake and not touching the accelerator pedal. I've even noticed that with the foot brake on, there's sometimes a random sharp drop in revs and a surge. Completely random so not easily repeatable in front of a technician.


Razza - All I can say is there is no "surging" with a properly functioning Mech.. unit. On a level suface the car will gently creep forward ..not surge. Find a slightly inclined road or parking lot near the dealer and repeat what I described before you take it in. Then show the technician how it drops in revs, shudders ..lurches forward in the area you performed the test..... If they say it's normal then demand to repeat the test with a demo DSG car...

In my case I had the transmission technician - he diagnosed it immediately - ask that a transmission tech look at it.


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## mikef4uk (Jan 15, 2006)

Razza said:


> Thanks. Will try that.
> 
> Should the car creep forward on a level surface? I get a forward surge after a second or so after releaseing the brake and not touching the accelerator pedal. I've even noticed that with the foot brake on, there's sometimes a random sharp drop in revs and a surge. Completely random so not easily repeatable in front of a technician.


Yes it should creep forward slowly, when mine was faulty it would start to creep then stop, the moment I then touched the accelerator pedal it would kangaroo (a little like a learner, so embarrassing in traffic)


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## sixdoublesix (Nov 3, 2009)

twocati said:


> My DSG was perfect but over time it became jerky and annoying during low speed parking or stop and go...I just assumed it was one of the quirks of the DSG..
> 
> My dealer diagnosed it within 3 minutes....the Mech.... unit was faulty. The car has been flawlwss since it was replaced...
> 
> ...


I thought that it was only held on a hill if you had the optional "hill hold" fitted?

jerking can also be caused by a loose cam chain or faulty cam chain tensioner and poor idle where the chain is slacker till the revs increase


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## Razza (Nov 23, 2010)

The problem is only noticeable when the car has warmed up. Would the belt expand when warm?


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## sixdoublesix (Nov 3, 2009)

Razza said:


> The problem is only noticeable when the car has warmed up. Would the belt expand when warm?


Cam chain only applies to V6 thou, IRC the S-Tronic is a bit jerky pulling away but its so smooth when driving, can hardly tell the gears have changed if it wasnt for the revs


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## mikef4uk (Jan 15, 2006)

sixdoublesix said:


> Razza said:
> 
> 
> > The problem is only noticeable when the car has warmed up. Would the belt expand when warm?
> ...


No, the DSG is not ''a bit jerky pulling away'' UNLESS ITS FAULTY, you need a new mechatronic unit, it's a unit that sits on the front of the gearbox and contains the ecu and all the hydraulic control valves, just get the car in for a new one you'll be amazed at how smooth it will be


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## powerplay (Feb 8, 2008)

Razza said:


> The problem is only noticeable when the car has warmed up.


I guarantee you 100% this is unquestionably the mechatronic control unit and nothing else. They can suffer from a faulty temperature sensor - hence the problem occurs when warm - causing the gearbox to incorrectly vary the clutch plate pressure, giving the symptoms you are experiencing.

From first-hand experience: replace the mechatronic unit under warranty for the totally smooth gearbox experience 8)


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## sixdoublesix (Nov 3, 2009)

mikef4uk said:


> sixdoublesix said:
> 
> 
> > Razza said:
> ...


There is a thread on this and there's a difference between jerking and engaging into first. If it's jerking up and down the gears then yes something is wrong. Pulling away might have s slight jerk if you have a heavy foot.


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## Americo (Jan 19, 2009)

I just received a letter in the mail about this from Audi stating that it affects a limited number of vehicles between the model years 2007 - 2009 and they will categorically replace any vehicle's Mechatronic unit that is showing signs of (jerking) the word they used! They said it is a 4 hour job and will issue a loaner if need be.
Mine has been fine but I do notice a wee bit of jerking between 1st and 2nd in traffic....I am uneasy about having them put their hands on my vehicle . :?


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## twocati (Dec 6, 2009)

> No, the DSG is not ''a bit jerky pulling away'' UNLESS ITS FAULTY, you need a new mechatronic unit, it's a unit that sits on the front of the gearbox and contains the ecu and all the hydraulic control valves, just get the car in for a new one you'll be amazed at how smooth it will be





> I guarantee you 100% this is unquestionably the mechatronic control unit and nothing else. They can suffer from a faulty temperature sensor - hence the problem occurs when warm - causing the gearbox to incorrectly vary the clutch plate pressure, giving the symptoms you are experiencing.
> 
> From first-hand experience: replace the mechatronic unit under warranty for the totally smooth gearbox experience


I agree also from first had experience with these posts.......Stop speculating and your next post should be the results of your dealer visit


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## twocati (Dec 6, 2009)

sixdoublesix said:


> twocati said:
> 
> 
> > My DSG was perfect but over time it became jerky and annoying during low speed parking or stop and go...I just assumed it was one of the quirks of the DSG..
> ...


You are correct ...I just wanted to make the point that the engine increaseses slightyl in RPM not to roll back and gently creeps forward - the main point is when you depress the accellerator, the RPMs increase and the car pulls away in a proper functioning Mechtronic unit where a malfunctioning on the RPMs drop momentarily, the car seems to jerk..then pull away.


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## Razza (Nov 23, 2010)

I did take the very welcomed advice on board and last week booked the car in for testing during the first week of Jan. So will keep you all posted as to the results. Sorry for not mentioning this in my previous post. This was the first time I heard it might be a belt issue hence me questioning it.

(I added other items to the list of faults including deformed leather seats and water running into boot.)


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## Tri-Chas (May 26, 2010)

I had this on my TT back in June this year 35K on the clock, the Mechatronic unit was at fault and the whole box was changed. Bought it from a main dealer two and a half years old, I had the car 2 weeks before I started reading posts on this forum and began to see a trend from other people.... Jerky and unreliable take off from standstill in first or reverse, it got worse as the engine warmed up, thats it mechatronic failure. Strangely it can be fine when cold, like when you just do a quick test drive. I had a thread called 'DSG Jerky Takeoff' which had some very helpful posts. VW know about it and should change it no questions asked. Happy days since changing. Get it in to your dealer ASAP and good luck.


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## Razza (Nov 23, 2010)

My car's been with the dealers in Cambridge for just under two days now and they haven't found a fault with the mechatronic or gearbox yet. This is despite it crawling up an incline without the accelerator and going into 2nd on their premises, all during a test drive with their master tech in the passenger seat. The techie said they would check the 'fast filling valves' and all the detailed readings using their diagnostic equipment. It sounds like they're really only going to rely on those findings.

Would you believe it, the car misbehaved on the way to the garage, making me look a right div pulling away from the lights, then seemed to improve after the Audi chap got in. Bugger.

Anyways, they'll keep the car till next Tuesday as they've ordered the rain gutters on the boot lid and driver's side saggy seat foam all on warranty... which is nice. However, it's very frustrating as they keep insisting 'lots of people dislike the DSG, but that's how they are'. They know I'm serious about this so I'll just have to persevere, perhaps notch it up a gear, keeping a detailed log of all the symptoms and how to reproduce it. So far I've described the symptoms in an email but not used any technical information from this forum or VAG websites. Worst case, I'll try my luck with Audi in Peterborough.


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## Inny (Jan 3, 2010)

I don't think a DSG can ever be as completely smooth as a torque-converter automatic from a stop. 
My TTS has that momentary pause after releasing the brake and the clutch engages (smoothly). I had an A3 loaner with DSG and there was NO pause - it seemed as though the clutch was engaging as I released the brake. I recall test driving the TT back in '06 when they first came out and that car behaved the same way.
Is the momentary pause in my TTS normal?


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## Razza (Nov 23, 2010)

Oh. Audi Cambridge could not find any fault with the unit and have confirmed that it is operating within the normal limits of that transmission and engine combination. Their transmissions expert (i.e. technician who has been trained to work on these DSG boxes) has had a look at the car and my findings and unfortunately that's the verdict they have returned.

Time to go around the loop again.


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## powerplay (Feb 8, 2008)

Unless they've tested it after a 30-50 mile drive when everything is fully warmed up and at temperature, if the failure is anything like mine then they won't spot it. Mine was fine from cold and for short runs, only on longer runs did it start to exibit the Mechatronic failure - it is a failure of a temperature sensor so that stands to reason.

You need to take it in to the dealer via the scenic route and have the Tech guy check it then.


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## zmoke (Jan 26, 2009)

It is very true that faulty mechatronic unit gets really bad when everything is hot.
Mine was also quite ok when cold - but after two laps in Nurburgring I could barely kangaroo car back to parking place!


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## Razza (Nov 23, 2010)

Visited Audi Peterborough today and had their transmissions expert Tony have a drive. As soon as he set off , he confirmed it was down to a faulty mechatronic unit. To keep a short story short, the car's booked in next week for writing up and submitting the diagnostics/DIS reports to Audi HQ.

Tony has replaced 2 mechatronic units in the last 5 years and knowing that really did set my mind at ease; no need to convince them that I wasn't imagining things. Once this has been fixed I'll let the Cambridge guys know so that they can 'learn' from the experience.

Hopefully a positive result soon...


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## BLinky (Jul 3, 2009)

Cambs Audi really is a joke, qouted me £600+ to service the A5 once.

edit: also scratched the side mirror.


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## Guille8-8-8 (May 16, 2012)

Americo said:


> I just received a letter in the mail about this from Audi stating that it affects a limited number of vehicles between the model years 2007 - 2009 and they will categorically replace any vehicle's Mechatronic unit that is showing signs of (jerking) the word they used! They said it is a 4 hour job and will issue a loaner if need be.
> Mine has been fine but I do notice a wee bit of jerking between 1st and 2nd in traffic....I am uneasy about having them put their hands on my vehicle . :?


My friend, "Americo". or any friend that can help me please!!
Hoping from you to read this post soon, i was wondering if you could help me.
Is it possible, you scan and send me the letter you received from Audi, regarding the jerking of the DSG gearbox, and the warranty Extension?
I found a VW letter, but i need the Audi one.
I have a DSG car too (A3 2008) but i haven´t received that letter, and my car is starting to jerk a lot, even more when it is hot, and now, in traffic jams, is getting very dangerous to accelerate and stop.

Please, help me out here, i really need that letter, so i can have a backup, if i bring the car to my local dealer.
Thanks, from Chile.


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