DSG getting jerky when engine is hot

[brinks787]

Hi,

I've owned my 2008 GTi for over 2 years now and bought it with around 39k on the clock.  It's now done 76k.

I had the DSG service done when I bought it so at the correct interval.  It's been great, mostly smooth and quiet and very well behaved.

Just recently over the last couple of months when the car has been stuck in slow moving traffic for a while and the engine is nice and hot it gets a bit jerky when setting off in first.  It goes with a jerk/clunk and then feels like the clutch hunts for the biting point a couple of times before it gets to grips with itself and then its fine.  Once on the move its fine and changes are smooth as butter.  When it's cold it's really smooth taking off even crawling from a standstill it has nice clutch control and no jerking.

Since I noticed this I had the 80k service done a bit early and included the DSG box oil change.  Didn't make any difference.

I then did the box calibration with VAGCOM as per this

http://wiki.ross-tech.com/wiki/index.php/6-Speed_Direct_Shift_Gearbox_(DSG/02E)

again, no difference.  Still plays up like a learner driver setting off in first when it's all hot.

I'm going to try the gearbox reset / calibration again tonight but am wondering if there are any parameters I could log to see if I can check whats going on with the gearbox when it's hot.  I was thinking about clutch pressure being a good one to check but I'm more concerned about the clunk.

Could the clunk be mechanical wear of some kind and the hunting clutch just be a consequence?  I'm thinking maybe gearbox mount or gearbox internal wear but I'm not sure how common these are on the GTi.

For what it's worth the gearbox whines a bit in first and second, you can't hear it normally but if you drive in an underground carpark with the window down it's quite noticeable.   A forum search shows this is fairly normal.

Any ideas where to go next, the car is perfectly driveable but it's a bit annoying if I'm in real heavy traffic with passengers.

Ideally I don't want to send off the mechatronics unit only for it to come back with no fault found.

[doylebros]

I assume the selection shows the fault only when going down from second to first and up from first to second with the second to first being the most noticeable for harshness?
If this is the case it will be faultless at normal temperature for up to two hours of driving then it changes to the rough selection mode.

[brinks787]

Not in my case, selection between gears is fine. 

The problem is setting off from a standstill, all the other selections are fine.  No warning lights or fault codes either.

I've tried in D, S and Manual and its the same in all.

[doylebros]

Since you've cleared that up its not one I've had so can't help you 

[slix]

Could it be a sticking caliper?

[brinks787]

Could it be a sticking caliper?

That's a possibility I hadn't thought of!  I'll check them but I did change the pads and discs all round myself not so long back and the calipers were in great shape.  Worth a look.

I've done the DSG reset again just now but it's fairly late here so no traffic to get stuck in.  All behaved well on the half hour drive afterwards.

If anyone else has VAG COM could they check the output of the brake pressure sensor for me (under ABS measurement blocks).  Mine sits at .5 ish bar when my foot is off the brake pedal and i'm not sure if that is normal or not.

[slix]

Did you do the defined drive after as said on wiki? Then it can learn the adaptations and clutch pressures. Don't have to do it as will learn over a period of time but best time do it in one go.

[brinks787]

Did you do the defined drive after as said on wiki? Then it can learn the adaptations and clutch pressures. Don't have to do it as will learn over a period of time but best time do it in one go.

I did, when I did the adaptation last night I followed it with the defined test drive exactly to the letter of the wiki.  Thanks for the suggestion.  I'm keeping my fingers crossed this 2nd adaptation run will cure it.

If anyone does get a chance to check their brake pressure with foot off the pedal I'd appreciate it though, here's a screenshot of mine.

[r5gtt]

Correct me if I'm wrong but I'm sure iirc the brakes were off when no pressure is applied and when you apply the brake you get a reading as I was messing around with vagcom not long back and checking abs brakes dsg in trans and the rest associated with out car.

[brinks787]

Thanks, that's what I was expecting.   The reading does go up if I step on the brake pedal but I was expecting to see zero rather than this reading when the brakes are off.   

Anyway, drove it all day today with no issues so maybe the second attempt at the DSG reset has worked - fingers crossed 

[r5gtt]

Good luck

[Leon_FR]

Thanks, that's what I was expecting.   The reading does go up if I step on the brake pedal but I was expecting to see zero rather than this reading when the brakes are off.   

Anyway, drove it all day today with no issues so maybe the second attempt at the DSG reset has worked - fingers crossed 

Hi Mate,

Just wondering how your DSG has behaved since? I have the exact issue with my 58 Leon FR Tsfi. I changed the oil thinking the consistency was affected when heated up, but made no change. The brakes sticking was a very interesting theory, so will be checking the resistance both before startup and Hot today. It drives perfectly if only short drive.
 Thanks in advance!

Don

[brinks787]

No luck I'm afraid.  I've driven it a fair bit this week and it's still playing up when it's been stuck in traffic for a while.

I'm looking to get it booked in somewhere for a proper look over before something goes bang.  The gearbox whine in 1st and 2nd may be related, perhaps it is a mechanical issue with the box rather than a mechatronic or control issue and the jerking is just a symptom.

I'll get in touch with these chaps and see what they think, just need to sort some time to get it booked in.  I've heard good things about them.

http://www.gearboxnottingham.co.uk/gearbox-dsg-repair

Also just waiting to hear back from these chaps as they're a lot closer to me, although I've not heard any reviews about them.

http://www.staautogearbox.co.uk/home

Other than that, I might sneak it in for another fluid change just in case the main dealer missed something or didn't do it properly a few weeks ago.

[brinks787]

Oh and I've checked the brakes, not seized or grabbing hot or cold.  Shame, it was a good shout.

[Leon_FR]

Gutter. Mine seems identical to yours. It's been jerky when hot since I purchased 14 months ago. Was noted on test drive as didn't get to hot. It seems to have got worse now tho and does have a quiet whine. One other thought I had was the idle rpm, as that's higher when cold.