audi a7 2016 biturbo rough idle and judder at 2000rpm on cold start

[naim-a7]

Hi all

Every time i cold start my Audi a7 biturbo (320PS) 2016, the idle is a little erratic once started. As I rev up to 2000rpm, the is a massive judder and the car shakes. however this is only when the car is stationary on cold start. if I drive away the car is fine and once the car is at operating temperature if I stop ad rev the car again there is no problems as if it magically disappeared.

There no lights on the dash and ran a diagnostic at a specialist in Peterborough which was pretty much a waste of time and money. The car drive fine however the rough start and the judder is something i would like to get rid of before it gets worse. i have notices the engine gets very hot after driving on the motorway and the fan turn on once the car has stopped but sound very loud...wonder if that has any affect to peoples thoughts however the temperature gauge goes up to half way and stays there.
any advice or tips would really help. not seen much on the biturbos on here so would especially the a7 !

 

[OolongA7]

The engine getting hot and the fans running will most likely be the ECU doing an Active DPF Regeneration cycle.
My BiTDI would do it regularly even though I gave the car a good 20 mile thrash every two weeks.

My car would occasionally misfire on start up, it would also do it when hot too. The dealership never did get to the bottom of it.

 

[AndyB40]

Hi all

Every time i cold start my Audi a7 biturbo (320PS) 2016, the idle is a little erratic once started. As I rev up to 2000rpm, the is a massive judder and the car shakes. however this is only when the car is stationary on cold start. if I drive away the car is fine and once the car is at operating temperature if I stop ad rev the car again there is no problems as if it magically disappeared.

There no lights on the dash and ran a diagnostic at a specialist in Peterborough which was pretty much a waste of time and money. The car drive fine however the rough start and the judder is something i would like to get rid of before it gets worse. i have notices the engine gets very hot after driving on the motorway and the fan turn on once the car has stopped but sound very loud...wonder if that has any affect to peoples thoughts however the temperature gauge goes up to half way and stays there.
any advice or tips would really help. not seen much on the biturbos on here so would especially the a7 !

I wouldn't worry about the engine getting hot and the fan being on when car stopped / turned off, that's the DPF doing its thing. The BiTDI seems to love doing a regen even if regularly driven on motorways. The original issue could be many things, where are you based? I would also try posting this question on the Audi A7 Owners Club facebook group (there are several), lots of knowledegable people on there who might be able to help.

 

[OolongA7]

This thread is well worth a read. It may have some answers for the problems you are experiencing.

Eliminate diesel clatter CDUC, CDUD 3.0tdi

Hi All Thought I’d share this with you in case it helps someone...... Has any 3.0tdi CDUC, CDUD owners who have higher mileage engines notice a more pronounced diesel clatter noise at idle or at low rpm and maybe notice the engine isn’t quite as smooth in low rpm as it used to be ?. Here may be...

www.audi-sport.net

I mentioned the issues within the above thread to the dealership that was attempting to sort problems with my A7 but they showed no interest, which didn't surprise me.
I even took a photo of the EGR outlet (located in the inlet trunking) that was caked in gundgy carbon residue. They implied it was perfectly normal and took no interest.
A lot of people have reported good results after cleaning the swirl flap and housing.

 

[naim-a7]

Do you think the open head coolant circuit would cus this problem

 

[OolongA7]

Personally I don't think a faulty cylinder head coolant control valve / thermostat would cause the symptoms you describe.
I would definitely make sure all is well with the swirl flap as per the link in the post above.
I think faulty fuel injectors may not always be highlighted with a DTC as in an effort to diagnose a problem with my BiTDI the dealership replaced all 6 injectors even though there were no DTC's indicating a problem in that area.

 

[billgatese30]

Could it be a vacuum leak?

 

[TedA6Avant]

I have the exact same idle issue with my 2017 A6 avant 3.0 biturbo. It's fine after warming up but idles "roughly" when first started. Not ridiculously roughly but enough to make me want to get to the bottom of it as I have just bought the thing!