5F DSG stutters with ACT mode in 7th gear, out of ideas

[Snackie]

Good day,

I am getting a bit desperate with my Seat Leon 1.4 TSI FR ACT DSG (5F, 2018). The car has been driving fabulously, when it drives fabulously. Unfortunately I am running into an issue which "does not always" occur but more often by the day. When driving on a highway between 95 and 130 kph, when the ACT mode is enabled the car just keeps continuesly deep stuttering (So no hard-biting immediate stutters, but I guess longer deep stutters ...). The feeling is a bit hard to explain.

* Stutters 95+ to 130 kph, ACT mode enabled, 7th gear.
* Both with throttle with the foot, as with adaptive cruise.
* Dissapears when I shift manually to 6th gear, even with ACT on in 6th.
* Dissapears when ACT turns off.
* Dissapears when accelerating.
* No RPM drops visible on the dash.
* No error codes.
* No weird noises/sounds audible.

The SEAT dealer has investigated twice and was unable to replicate the issue, but the first time they did a reset to basic on the DSG transmission. This seemed to have solved it, but could just as well been a coincidence. Now the dealer is out of ideas, and want me to replace the DSG clutch. I myself are unsure and more leaning towards some issue with the ACT system. But as a non-mechanic I have absolutely no idea how this system works and if its even feasible.

I am very much open for ideas. Thanks for reading!

 

[nd-photo.nl]

DSG adaptation reset can mask bad behaviour and that is exactly what happened in your case. The adaptations are learned again by driving over time and if there is something wrong, it will just happen again.

If the DSG reset solved it temporarily, it makes sense to look in that direction. I would recommend a specialist like TVS engineering, or contact AGS in Veghel (https://automaticgearboxservices.com/) for some advice.

I went to AGS for a full gearbox rebuild with my Mercedes, but they also have a lot of DSG knowledge. Might be something with the solenoids and not the clutches.

 

[Mr Pig]

Dealers are hopeless and disinterested when it comes to issues like this. There won't be anyone at the dealership who's qualified to diagnose the fault. Saying they can't replicate it is a common tactic. I had to take a video of a faulty touchscreen on my wife's car before they would accept there was a problem.

Has the timing belt been changed? It should have been done at five years. I don't think that the timing belt would cause this issue but if you get it done it would give a tech the chance to have a look at the act system in case there is something wrong. The set up of the system has to be very precise and they check that as part of the belt replacement.

 

[Glosphil]

The timing belt on a 2018 1.4TSi ACT engine does NOT need changing every 5 years. It needs checking at 130,000km.

OP has a strange fault at only happens with ACT active & in 7th gear?

 

[Mr Pig]

The timing belt on a 2018 1.4TSi ACT engine does NOT need changing every 5 years. It needs checking at 130,000km.

I know they've changed the advice but I'm not inclined to leave a timing belt until some tyre monkey at a dealership notices that it's coming apart. The car's coming up on seven years old, which is two years past where VW used to recommend replacing the belt. I would change it.

My point is that if you ask a tech to check the ACT system they're going to pull it apart and charge you a lot of money. If you get the belt done and ask them to check the ACT system at the same time it'll cost you more but you're getting something done for your money.

I think the hard part will be finding someone who's got half a chance of finding the fault. Most dealers are out. I'd be looking at an independent VW specialist.

 

[Snackie]

Currently the car is at TVS engineering which are specialized in DSG issues (And much more), and I have high hopes for them finding the issue, cause and hopefully a solution. Trying multiple angles here, and hoping "someone" who reads this has any clue or "I've seen this before" kind of reaction. Thanks for the responses so far!

The car has not much mileage on it either, around 42k kilometers.

 

[nd-photo.nl]

Ah ok, good. Keep us up to date! If they cant find anything, consider contacting AGS like I mentioned earlier