Unexplained slow down during cruise control

[Ian Trotter]

Hi there, although this is my first post I find it hard to believe that I'm the only one to have experienced this issue with our Q7. I can't find any similar threads though.

When driving around on motorways it has unexpectedly slowed down significantly (once to 36mph when set at 70!) without obvious cause. Yes I know the car has adaptive cruise but there are no other vehicles around at the time. I have noticed this several times with one location being quite close to home. It is a fully repeatable behaviour, when approaching a point on the A1 (either Northbound or Southbound) where there is a road bridge over the top of it, the car will progressively slow down unless the driver intervenes. As soon as the car passes under the bridge the vehicle returns to the pre-set speed.

I have reported this to my local dealer where the master tech. thought it might be a weak signal from the GPS aerial resulting in a positional error but I don't think that is the case. The satnav doesn't go 'off road' in places where it shouldn't. The car was in the dealers for a day and I also showed video recordings of the behaviour over a month ago but to date I haven't had any feedback despite chasing up several times.

The 'slow down' does not happen if the 'Adaptation to route ahead' feature is disabled under 'Driver Assist / Adaptive Cruise Control'.

I see this as being potentially dangerous as drivers behind will not expect a car to slow down so significantly without reason creating a hazard.

I believe that the issue relates to the Satnav map data and have looked at the map info from within HERE Map Creator which is jointly owned by Audi / BMW / Daimler. At this point the sections of the A1 have end nodes where the Serlby Road crosses over it which also has end nodes at each 'intersection' and is not defined as an 'overpass' as it should be. Therefor I think the car sees it as a junction and slows down in preparation for it. If my theory is correct then any other Q7 with either the Dynamic Pack or Tour Pack should be doing the same.

Has anyone else experienced similar unexpected behaviour whilst in cruise control?

Ian T.

[maxw]

Hi
im afraid must of us on here with adaptive cruse have this prob this seem to happen in the same places if it happens on a route to work or
a route you travel often your find it does it in the same spots

the thing that is happening is for some reason either on gps or the maps the car adapts via cruse to the route ahead and for some reason the car is detecting either a sharp bend or junction or roundabout when this happen it will show a symbol on the dash beside the lane gidence symbol And cruse symbol

not sure if it's partly to do with the road layout has chnged over the years or speed has change not sure
one place mine always happen is when I'm going by a slip road on a duel carriageway but I keep on the duel carriageway and go underneath the roundabout interchange and the car thinks I've gone up the slip road but have also had it happen on a straight section of road with nothing about

fix
there isn't one at the moment
you have 2 choices
either switch off adapt to route ahead in the mmi
or like most off us do is just put your foot on the throttle for a min or so

like most of us we all got odd bugs in the system and I have quite a few

sorry I can't fix things but least it will explain what is going on

hope this helps

M

[Ian Trotter]

Thank you Maxw,
Your comments are very much what I had expected, the only surprise was that I couldn't find much previous discussion on the subject, since as you say anyone with adaptive cruise should be affected.
I agree that there is no simple solution since if we're both right the cause lies in the map data not the cars themselves (although Audi do jointly own the source of this data as I mentioned).
Cheers,
Ian T.

[Ian Trotter]

Hi again everyone,

I've had a reply (stall) from Audi Customer Services about this behaviour with them asking me to identify other specific locations where it happens. Although I have experienced it several times, there is only one regular / local point that I can currently conclusively point to. Could anyone post known locations of similar behaviour that I could pass on?

Thanks,
Ian T.

[maxw]

Only one known regular spot like you

A14 west bound going past A12 copdock interchange slip road

also happen near Royston on the A505 but not sure I could pin point the spot
thanks

M

[Nemo78]

I have it various places but have learnt to adapt to it as mentioned above...it's the problem with too much technology unfortunately

[Ian Trotter]

Thanks maxw, I've had a very quick look at the map data at the A14 / A12 junction but can't spot anything as obvious as my location, if you go down past Royston I'd be grateful if you tried to identify the spot.

Nemo78, could you possibly identify any of the locations you know of? I agree that some things are simply trying to be too clever, but if we don't push for them to be debugged then progress will be slower.

Cheers,
Ian T.