Audi A8 2.8 running issue

[steamship]

Originally Posted by Audi Doody

fingers crossed it's not the throttle body as they're big bucks aren't they

Oh and the cruise control switch was flagged as broken- makes sense as cruise control doesn't work - do I just need a new stalk?

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They might even have the cruise control stalk.

[HPsauce]

Cruise control has two fundamentally different versions, which depends on the age of your car. As I think is flagged prominently on the forum, it helps if you supply more details of your car as answers do depend on precise vintage, trims, etc.

[Audi Doody]

Originally Posted by HPsauce

Cruise control has two fundamentally different versions, which depends on the age of your car. As I think is flagged prominently on the forum, it helps if you supply more details of your car as answers do depend on precise vintage, trims, etc.

Ah ok makes sense:
W reg (2000) 2.8 FWD. Not a sport although has 18" sport wheels

[HPsauce]

2000 should be the "drive by wire" throttle where cruise control is just a bit of software in the ECU. Earlier versions actually had a separate box in the engine bay ECU box and that really could go wrong.

As such, with DBW, the switches on the stalk talk directly to the engine ECU and are pretty simple.
They often get gunged up, spraying with contact cleaner and energetically exercising them can often bring them back to life.
Unless of course they really are broken, but all that VCDS (or any other diagnostic) can tell you is whether it sees the switches operate, not that they are "broken" so this is always worth a try.

Do any of the cruise control functions work ever? Mine didn't when I got the car and it was the end button that wouldn't "set" a speed, so it never worked until I cleaned and "exercised" it.

[Audi Doody]

That's interesting, I'll have a play with the set button. Thank you!!
The previous owner mentioned that the 'set' button worked, but you could increase the speed. None of the cruise control has worked since I've owned it, which is since May only. Best car I've ever had for motorway duties.

[HPsauce]

Mine's still not great on increasing speed (or resuming), sometimes it just disengages.
So I'm more in the habit of increasing with my right foot (which is actually easier than that horrid little slider anyway) and pressing set again.

I think my slider switch is the least reliable bit so I just leave it permanently in the "on" position. Beating the hell out of the end button got mine working reasonably reliably in the end and you can live without the rest.

[Audi Doody]

The garage have stated that the faults are from the throttle body, so a new one is being fitted. £350 for a new genuine Bosch item. The main dealer wanted 900 quid!!!