alastaid
Member Since: 31 May 2011
Location: York
Posts: 93
  
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| Cruise Control "Hesistation" |
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Hi,
Latest little issue my car has come up with is the cruise control. So I have noticed recently that when cruising on the motorway between 70 & 80, every so often you feel the car back off slightly and then feel the slight clunk as transmission picks up again and brings it back up to speed. I started counting this and it is mostly around a 10 second cycle, but not every time. It drops by about 1mph and then you feel the car accelerate to get back up to speed. Now until now cruise on the motorway has been silky smooth.
To try and isolate:
If I turn off cruise and drive steadily at that speed on the throttle, completely smooth.
If I override cruise with the throttle and drive just slightly above the cruise speed, again completely smooth.
If I put it in command shift, no difference it still hesitates every 10 seconds.
If I cruise at a lower speed say 50mph, its completely smooth.
So I was wondering what systems interact with cruise and what it could be.
One suspicion I have, which someone here can probably dispel or confirm, is as the car is fairly high mileage (70k and just over 3yrs old), it has developed a slight slackness in the transmission take up, if you are just crawling along in traffic and then put your foot down slightly too hard, there is quite a clunk of the transmission picking up, I was wondering if there enough “play†in the transmission to allow the car to slow down at high cruise speeds and then it realises it is dropping speed, and compensates?
Also, no noticeable drop in fuel consumption, no fault bongs, warning messages, and it still pulls like a train when you put your foot down.
Any ideas, things to try?
Cheers
Alastair
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 26th Jun 2013 9:39 am |
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alastaid
Member Since: 31 May 2011
Location: York
Posts: 93
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OK bizarrely driven 250 miles today and its perfect again, so just have to put it down to the enjoyment of owning a disco.
Cheers
Alastair
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| 27th Jun 2013 3:12 pm |
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Disco4Ray
Member Since: 22 Apr 2013
Location: Braintree
Posts: 9
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I've had exactly the same problem but mine has only 25k on the clock.
Guess we will never know!
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| 27th Jun 2013 5:07 pm |
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A1GSS
Member Since: 12 Sep 2010
Location: Saffron Walden, Essex
Posts: 4691
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One possible idea.
My Audi did this, almost identical symptoms. The cause was the fact that I'd just changed the wheels over (winter to summer) and had forgotten to reset the tyre pressure monitoring system and Nav, both of which rely on counting wheel revs and comparing with actual speed. For some reason, when the computed speed (from wheel revs) didn't quite tally with the GPS speed (from satellites), it spooked the cruise control.
Solution was recalibration, from the system menu. ____
Gone: 10MY L320 RR Sport HSE, Ipanema Sand
Gone: 20MY Jaguar iPace HSE, Silicon Silver
Gone: 17MY RR Evoque SE Tech, Loire Blue
Gone: 08MY Discovery 3 XS, Stornoway Grey
Gone: 07MY FFRR TDV8 Vogue, Stornoway Grey
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| 27th Jun 2013 5:19 pm |
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