Quick question about 6sp auto on C5

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aerodynamica
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Quick question about 6sp auto on C5

Post by aerodynamica »

Hi all, generally the C5 is going well but I notice that sometimes there seems to be a kind of delay in throttle response where you've rolled to a near stop and go to accelerate away again e.g at the end of an off slip where the lights change before you stop.
It looks like it doesn't reach first gear early enough and it's still in D2 at near 0 mph . It then will rev quite high as if it panics and goes into kick down where it then goes like stink and even caused the esp light to come on in the dry.... there were no faults in the last global scan.
Is this unusual? Or am I just not used to this car yet. I've mostly had manuals and my only 2 previous autos were a xantia and XM. The XM had a ZF 4 speed of the old style and always reached 1st gear by the time of slowed to a crawl even after an hour at motorway speed. Even though it was a less refined transmission.
Otherwise the c5 auto seems well with all the up changes seemless. I have no record of the trans oil being changed and I'll assume it has never been changed despite being one of the older X7s about. I've read up on her about the 3 stage process of fluid change and the fact that it is different fluid for the same transmission where it's euro 4 or 5.
Does the c5 (hdi 138) use a throttle position sensor at the pedal? Could this be going?
wheeler
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Re: Quick question about 6sp auto on C5

Post by wheeler »

aerodynamica wrote:
29 Dec 2021, 10:42

Does the c5 (hdi 138) use a throttle position sensor at the pedal? Could this be going?
Yes it does. Its certainly not a common failing part on this car & I would think you would have other symptoms too. There would also highly likley to have a fault code and engine warning light on.
aerodynamica
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Re: Quick question about 6sp auto on C5

Post by aerodynamica »

Yes I suppose it would have symptoms at all times and the throttle response is fine all the time. Maybe the box is in need of the fluid change after all..
Ed81ie
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Re: Quick question about 6sp auto on C5

Post by Ed81ie »

My 6 speed auto box on C4 Grand Picasso do not change down fast enough as well, and few times stalled because of that. It feels that robot gets slower on down changing.

More here
viewtopic.php?t=70257
aerodynamica
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Re: Quick question about 6sp auto on C5

Post by aerodynamica »

Thanks, just read yours and sounds worse - mine still drives ok overall. I hope it's not getting as bad! Good luck fixing it
admiral51
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Re: Quick question about 6sp auto on C5

Post by admiral51 »

Not too clued up on the auto boxes but is it an adaptive ECU, the type that will learn how the vehicle is driven over time and hold gears for longer etc etc.

Just thinking that depending on how the car has been driven in the past which we do not know, could it now be as aero says it goes into a panic as it doesn't understand it is now being driven by a boy racer off the lights :rofl2:

Mainly serious and just a little bit of fun about the lights but i see no real issue with rolling up to the lights in 2nd and pulling away without changing down to 1st in a manual if i haven't stopped so why not in an auto box
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Re: Quick question about 6sp auto on C5

Post by aerodynamica »

admiral51 wrote:
29 Dec 2021, 20:04
Not too clued up on the auto boxes but is it an adaptive ECU, the type that will learn how the vehicle is driven over time and hold gears for longer etc etc.

Just thinking that depending on how the car has been driven in the past which we do not know, could it now be as aero says it goes into a panic as it doesn't understand it is now being driven by a boy racer off the lights :rofl2:

Mainly serious and just a little bit of fun about the lights but i see no real issue with rolling up to the lights in 2nd and pulling away without changing down to 1st in a manual if i haven't stopped so why not in an auto box
Colin
Ha 🤣 seems you have seen me drive then 😜
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Hell Razor5543
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Re: Quick question about 6sp auto on C5

Post by Hell Razor5543 »

There may be a way to reset the auto adaptive settings, so that the car then goes back to the factory default. After that it then starts 'learning' your driving style. I don't know HOW this is done, but you might want to give Mandrake (Simon) a shout, as he has had to do this on his Xantia a few times.
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GiveMeABreak
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Re: Quick question about 6sp auto on C5

Post by GiveMeABreak »

This is an AM6 box. You don't need to do anything except when either the gearbox ECU or the gearbox is replaced or when the oil is changed. All the process involves is driving with frequent gear changes to obtain satisfactory gear changes, which the gearbox ECU will adapt to.
aerodynamica
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Re: Quick question about 6sp auto on C5

Post by aerodynamica »

Yes, to be honest it is working quite well- I use a lighter foot pulling away now and it actually seems to respond better. I think that really I was not used to it after driving the manual Xantia for 5 years.
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xantia_v6
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Re: Quick question about 6sp auto on C5

Post by xantia_v6 »

To clear up a bit of confusion, modern automatic transmissions generally have two independent types of auto adaptive. The one that is visible to the user is an adjustment of the gear change points according to the recent driving style of the driver. This has quite a short memory, and adapts within minutes.

The other is the shift pressure adaption that affects how changes are made, and it compensates for manufacturing tolerances and component wear over the life of the transmission. This has a long memory, maybe hundreds of miles, and is the one that must be reset when components are replaced.
admiral51
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Re: Quick question about 6sp auto on C5

Post by admiral51 »

aerodynamica wrote:
31 Dec 2021, 19:09
Yes, to be honest it is working quite well- I use a lighter foot pulling away now and it actually seems to respond better. I think that really I was not used to it after driving the manual Xantia for 5 years.
Sorry aero looks like you are losing your "Boy Racer " tag :rofl2:

Xantia_V6 thanks for explaining the difference between the adaptive ECU =D>

Colin