C5 4 speed automatic

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Tintin
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C5 4 speed automatic

Post by Tintin » 12 Dec 2014, 20:36

Hi everyone,

I'm new to this forum. I am just asking for advice on my newly acquired Citroen C5 HDI 4 speed Auto. Not owning one of these before, or indeed any French car, find the auto box quite perculiar. All gears are working but the box seems to prefer downshifting to a lower gear, especially at city speeds and lifting off on a downhill run. This can make the drive quite uncomfortable sometimes. I am thinking of changing the transmission fluid as the car has done 220000kms and hoping this May help. The question is this normal for this gearbox or is there something wrong??
Many thanks

citroenxm
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Re: C5 4 speed automatic

Post by citroenxm » 12 Dec 2014, 20:43

Welcome to our fold.

How old is the C5? Though, asking that, 4 speed is the give away. The proper question is which hdi engine, 2.2 16v or 2.0 8v engine??

The 2.2 16v hdi uses the ZF 4HP 20 auto adaptive auto box, where the 2.0 8v HDi uses PSA's AL4 auto adaptive box.

The two box's are simmilar by being auto adaptive, this means it "Learns" the drivers style and adapts to the style. They are designed to change down on over run to assist with engine braking..

Im not positive, but you can reset the parameters on the box, but Im not sure if its simply battery disconnect for a certain amount of time, or only through a lexia diagnostic.

ALSO: The gearboxs DO NOT USE DEXRON fluid, they use a special fluid Esso LT14414 (Or something like that!) DO NOT USE DEXRON in them!!!

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Tintin
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Re: C5 4 speed automatic

Post by Tintin » 12 Dec 2014, 20:59

Thank you citroenxm.
My car is a 2.2 16v HDI 2002. Your answer makes sense to me as the car was used as a "runaround" in a quiet coastal town for a couple of years by its previous owner, only very short runs at lower speeds. This may have effected its "learning". What do you think?

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Re: C5 4 speed automatic

Post by citroenxm » 12 Dec 2014, 21:06

Ooooo the WORSE engine for the WORSE type of journeys!! 2.2s just do NOT Like short journeys. You will need to do a good FEW high speed runs to get the DPF cleared out

The gearboxs also use an Electronic lockup on the torque convertor... the electro valve that controls it can play up. It results in the engine always dropping to Idle Revs every time you lift off..

At the moment it sounds like it is behaving correctly. Dont fret, we have a residant 2 HP 20 expert on here, who is currently out at the moment!

Im sure he would be able to give you a better more correct answer then me.

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Tintin
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Re: C5 4 speed automatic

Post by Tintin » 12 Dec 2014, 21:13

Thanks again citroenxm.

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Re: C5 4 speed automatic

Post by myglaren » 12 Dec 2014, 21:52

citroenxm wrote:Welcome to our fold.
From a Welshman to an Australian that is brilliant Paul! :rofl2:

Welcome TinTin :welc: :)

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Re: C5 4 speed automatic

Post by citroenxm » 12 Dec 2014, 21:55

myglaren wrote:
citroenxm wrote:Welcome to our fold.
From a Welshman to an Australian that is brilliant Paul! :rofl2:

Welcome TinTin :welc: :)
Oooo wasnt trying steve. I just meant welcome to the forum... :o :shock:

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C5 4 speed automatic

Post by addo » 13 Dec 2014, 00:04

You don't have to worry too much about the road usage there Paul; Adelaide is about like Taunton with a few extra hills chucked in. Not as though there would be prolonged periods of creeping bumper-to-bumper.

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Mandrake
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Re: C5 4 speed automatic

Post by Mandrake » 14 Dec 2014, 00:15

At that mileage I'd get an oil change done ASAP. Make sure you only use Mobil LT71141 as the 4HP20 is very fussy about it's oil, and putting the wrong stuff in (IE anything Dexron) could quickly kill it, especially at that high mileage...If the gear changes are a bit harsh or abrupt an oil change is likely to improve the changes.

Somewhat aggressive down changing when you're going down hill is normal for a 4HP20, depending on your driving style. It monitors the brake light switch and can also work out whether the car is going downhill, on the level or uphill based on the vehicle acceleration/deceleration, engine torque figure and throttle opening.

For example if it senses that the throttle is closed, the engine is producing no torque yet the vehicle speed is increasing it surmises that you are on the overrun going down hill. When you are going downhill or uphill it will hold lower gears to a higher rpm than if you are on the level, and will also down change earlier. Also if you are going down hill and you then apply the brake for more than about a second this will typically trigger a forced down shift and torque converter lockup to provide engine braking. This is normal behaviour.

There are two aspects to the "auto adaptive" features of the box. One is adapting to driving style, the other is adapting to wear and tear of the gearbox.

The driving "auto adaptive" feature monitors your driving style, primarily by how aggressively you operate the accelerator, and uses that to select different sportiness programs from SK1 to SK6 as you drive - with SK1 affectionately being referred to as "old git mode" where it will try to change up to a high gear really early, (below 2000 rpm) stay in high gears as much as possible, and resist down shifting, all the way up to SK6 where gears will be held to about 3500 rpm with very aggressive down shifting on the deceleration.

From a cold start you will start in SK2 but it will slip back to SK1 within a few minutes if you drive like a grandpa. If you drive aggressively it will go up to SK3 or SK4, and if you put it in sport mode it will stay locked in SK5 and SK6.

It's not just looking at how far down you press the accelerator, it's looking at how quickly you move it. Frequent rapid movements of the accelerator trigger switches to more sporty programs... also a quick kick down will kick down more easily than a slow acceleration - for example at a certain road speed in 4th if you slowly press the pedal down to 50% it may not kick down but quickly flicking the pedal down to 50% probably will. If you want it to change gear in a sporty fashion you need to flick the throttle quickly, unlike older hydraulic only boxes where only the distance moved by the throttle matters in triggering a kick down.

There is no way to reset the driver auto adaptive program, but you don't need to as it is constantly changing as it monitors your driving style and will adapt to either leisurely or aggressive driving style within a few minutes.

The other auto adaptive feature is adapting to wear and tear of the gearbox to maintain smooth gear changes - this happens gradually during the life of the car and there is an "auto adaptive reset" that can be done using a Lexia however in most circumstances I would NOT recommend this is done - as unless you follow a specific driving regimen for the first 20 minutes or so after the reset you can easily make the quality of the gear changes much worse, especially on a worn box.

Regarding citroenxm's comments on the revs dropping to idle when lifting off the throttle - that's actually normal on the 4HP20 depending on the speed you're doing and what gear you're in. Below a certain road speed for each gear the torque converter will unlock to increase pickup on acceleration, but that also means that if you let off the throttle the engine will drop to nearly idle and you will coast along.

Change down a gear and the road speed will be fast enough to put the torque converter into lock up mode - now releasing the throttle will maintain the engine RPM and you will also have engine braking.

I find on mine if I leave it in drive then it changes up to 4th at just under 40mph, but will leave the torque converter unlocked until about 50mph - so if I cruise at 40mph and release the throttle it will coast along with the engine idling, however if I manually change down to 3rd at the same speed the torque converter will lock up and the engine revs will not drop when releasing the throttle. As far as I know this is normal behaviour for a 4HP20 but I don't know if the AL4 behaves the same way...

I believe the 4HP20 is the first generation of fully ECU controlled gearboxes made by ZF, so in many ways its a "prototype" - I don't think it's a box that anyone loves, and the auto adaptive driver response is very quirky, the gear change thresholds a bit odd, (it really does try to slog the engine at low rpm all the time unless you maintain an aggressive driving style to keep it in a sportier SK mode) but you do learn its quirks and get to know how to get it to do what you want, even if that means a bit of manual use of the sport button and gear lever.

I absolutely love the engine in the Xantia V6 but I only tolerate the gearbox. Even a good one is not as smooth as more modern auto boxes and I'd far rather have a manual box in mine...

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Tintin
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Re: C5 4 speed automatic

Post by Tintin » 14 Dec 2014, 08:42

Thanks very much Simon for your useful info. Will be changing the fluid in the transmission tomorrow.

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Mandrake
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Re: C5 4 speed automatic

Post by Mandrake » 14 Dec 2014, 09:04

Do you have the method for how to do it ? Later versions of the gearbox like yours don't have a dipstick to set the level, instead there is a level plug a bit like a manual gearbox and you fill it via the breather vent at the top.

Here is the procedure for late Xantia V6's without a dipstick, it should be the same for your C4, assuming it is actually a 4HP20 and not an AL4.

https://dl.dropboxusercontent.com/u/782 ... %20Oil.pdf" onclick="window.open(this.href);return false;

The alternative is to measure how much comes out and replace the same amount but that assumes the correct amount is in there now...
Last edited by Mandrake on 14 Dec 2014, 10:31, edited 1 time in total.

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Tintin
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Re: C5 4 speed automatic

Post by Tintin » 14 Dec 2014, 10:24

Thanks Simon,
I've been crawling under the car to get an idea of what I need to do but this excellent guide is most helpful for the task ahead.
Craig

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Ben82
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Re: C5 4 speed automatic

Post by Ben82 » 14 Dec 2014, 12:40

Getting to the oil level plug isn't easy. I have some pics of where it is on my C5 V6, which hopefully will make it a bit easier to locate:

http://imgur.com/a/2rbGy" onclick="window.open(this.href);return false;

The 2.2 doesn't have as much exhaust piping getting in the way so it should be easier. Bandit12 has done the 4HP20 oil change twice on his 2.2 (once with me present), so I will ping him a message to see if he has any advice on it.

Also one thing that wasn't obvious to me, was the oil level plug is for draining excess oil to get it down to a specific level rather than for checking the level. So ideally you want it going from a small flow of oil coming out to just drips.

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CitroJim
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Re: C5 4 speed automatic

Post by CitroJim » 14 Dec 2014, 13:27

TinTin, welcome :-D If you log onto Club-XM.co.uk you'll find your old Pal Captain Haddock there :wink:

Simon, an excellent essay on the HP20 and worthy of Professor Calculus :-D
Mandrake wrote: I believe the 4HP20 is the first generation of fully ECU controlled gearboxes made by ZF, so in many ways its a "prototype" - I don't think it's a box that anyone loves
Speak for yourself! I love them to bits after rebuilding three of them. They are a work of mechanical beauty and poetry in motion :-D

TimTin, if you care to know more of the internals and how to rebuild one may I direct you here: HP20 Rebuild Guide

I believe there's a couple of broken links in that article I really ought to fix...

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myglaren
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Re: C5 4 speed automatic

Post by myglaren » 14 Dec 2014, 14:11

CitroJim wrote:
Speak for yourself! I love them to bits after rebuilding three of them. They are a work of mechanical beauty and poetry in motion :-D
I watched the YT clip of Jay Leno's Lancia Fulvia (from the '14' thread) and I think it was the same ZF box he was quite rhapsodical about.
Unless it was the one in the DeTomaso Pantera (always lusted after one, in preference to a Porsche or Ferrari)