C5 X7 hydractive mode *always* in "Poor Road"?

[Marciorschneider]

Hi folks! How are you doing?

This is my first post. I live in Brazil and own a C5 X7 hydractive exclusive 2012 for about a year, love the car!

Since I bought it I did notice that when stopping at a red light the front lowers a bit, with no reason.

Today I was investigating it with diagbox and found that the parameter "road condition" is *always* "poor road". It could be parked on my garage, driving at 30 Kh/H or even 120Km/H, the status is "poor road", as you can see:

Checked the faults, but nothing relevant there. Is this right? I believe that the parameter should be "normal road" when parked or driving on a good road.

Thank you guys!

[GiveMeABreak]

I wouldn't worry about it, that seems perfectly normal. Many of us have the same reading on our X7s.

The car will sometimes raise or lower itself slightly when coming to a halt and also when turning the steering wheel when stationary.

[Marciorschneider]

Thank you Marc, do you know how the hydractive decides to use "normal road" or "poor road"?

[GiveMeABreak]

Hi, the ECU has a set of 'rules' or 'laws' most likely, that depend on information collected from the ABS / ESP, engine ECU, Steering angle sensor, height correctors etc., which determine when the car is raised slightly, at normal ride height, or lowered on good motorway roads at 70MPH or the equivalent in KMH.

There are a set of these laws that also determine the specific Comfort and Sport mode settings on Hydractive 3+ systems too.

I suspect that unless you have perfectly smooth tarmac roads, with no hills or bends, just about most of is with these cars will have 'Poor' roads!

[Sloppysod]

Hi,
The X7 normally travels at 'So high' from the ground, however, when you hit 70mph (UK) the suspension drops by about 15mm (front) and 11mm (rear) to improve fuel consumption and further enhance stability.
So
According to the hand book
Maximum height - Workshop
Intermediate position - Off road
Normal road position - Poor road
After 70 mph has been reached then >50 mph - Motorway . - Could this be the actual Good road setting, they could hardly call poor road normal could they?
Minimum height - Workshop
Just a thought.

Does anyone has the actual ground clearances in Normal?

[jgra1]

my x7 is the same..'poor road' even at higher speed on a good surface... (saying that I cannot remember if I tried it at 70+mph..unlikely that I did on that occasion..)

[GiveMeABreak]

Hi,
The X7 normally travels at 'So high' from the ground, however, when you hit 70mph (UK) the suspension drops by about 15mm (front) and 11mm (rear) to improve fuel consumption and further enhance stability.
Does anyone has the actual ground clearances in Normal?

The car lowers by 10 mm on the X7 Stu at speeds of over 110 km/h

OK, I think the OP is referring to the car lowering slightly at the lights for example. This is all part of the height correction calculations made by the system when certain conditions are met and without making it too complicated: and please note - this applies to the C5 X7 Hydractive 3+ system.

The Height Regulation controlled by the BHI makes the height corrections to the ground clearances in the following cases:

• When the difference between the front or rear reference height and the actual ride height is more than -4mm and 4mm (hysteresis).
• When the difference between the front and rear heights are more than 8mm.

The system takes into account the average height of the body to eliminate 'interference' and current travel values. There is a timed period referred to as the 'dashpot' which is applied between the time the system detects the body is outside of the hysteresis zone and the time when height correction operates - in accordance with the following:

• On starting - a timed period of 0.5 of a second, when the driver requests a height change - or when the BHI ECU is triggered for 'height correction'
• When the vehicle has been driven and becomes stationary with engine running - the timed period is 60 seconds
• In other cases the period is 10 seconds

Note the height correction above can only be modified whilst the car is in 'soft' mode setting.

Concerning Automatic Modification of Body Height in Relation to the Road Conditions:
The 'Poor Road' status is detected if the wheel travel exceeds a threshold determined by a range of frequencies between 4 and 8Hz.

When 'difficult' or 'poor road' conditions are detected below 40 Km/h, the vehicle's ride height increases by 10mm - this position improves comfort and is referred to as 'pseudo road'.

Wheel travel values are determined by the 'heights monitoring' module. This is the wheel travel information in relation to the vehicle speed. Wheel travel values are placed into either

• Normal Road
• Driving over Obstacles ('wheel knocks')
• Road in Poor Condition

So going back to the OP's original question, when the car comes to a standstill like at traffic lights, the system will perform a height correction - and this is why the car will normally lower back down slightly (or rise) depending on the height calculations.

[Sloppysod]

Thanks for the information, yes the original question was "Since I bought it I did notice that when stopping at a red light the front lowers a bit, with no reason", but as usual of on a tangent we go........., however, we now have an insight into the logic behind the Hydractive 3+ suspension on the X7.

[GiveMeABreak]

I know it's a bit long Stu A long way about saying it is supposed to do that as I think I said in my first post - but at least it may help understanding of the system as you say.

[Hell Razor5543]

Simply put, Citroen is a French make of car, and the French are a law unto themselves. As a consequence, Citroens do things just because they can (and to wind up their owners).

[Marciorschneider]

Thank you all for your replies, very good info!

[AlvinCitroenC5]

Hi,

I recently purchased a used 2005 C5 3.0 V6 petrol, and each time when I stop at a red light, after 5 seconds the front suspension will lower itself a little, and obviously, the front suspension raises itself a little again when the car is back in motion. Is this normal? Thanks.

[GiveMeABreak]

Hi,

I recently purchased a used 2005 C5 3.0 V6 petrol, and each time when I stop at a red light, after 5 seconds the front suspension will lower itself a little, and obviously, the front suspension raises itself a little again when the car is back in motion. Is this normal? Thanks.

Your answer is here in this topic, so I have moved your post.

[AlvinCitroenC5]

Since I bought the car, I have noticed also all 4 tires have more wear on the outside. I have bought new arms, balls joints and drop links, and replaced all four tires. In addition, when going over bumps, I can feel that there is something loose and rattling in the steering column where the headlight assembly is. I suspect that the steering angle sensor is intergrated into the headlight/signal/washer stalk assembly? If so, could this "play" and rattling cause the BSI to think that the vehicle is on bad road ? Leading the vehicle always riding high? And leading to all 4 tires to wear more on the outside because of the change in wheel alignment geometry? Thank you for your advice and help.

[GiveMeABreak]

The steering wheel angle sensor is incorporated into the Comms unit ( inside the unit that contains the indicators and wipers) If the steering angle sensor was playing up, you would be getting 'ESP / ABS System Faulty' errors and it would then need recalibrating or looking at. If you are not getting these warnings,m then that is fine. My previous (MK I and MK II) C5s always went through tyres very quickly. The best thing you can do is get it tracked properly and have the driveshafts looked at too. Regularly checking tyre pressures can help.

The BSI gets information from many sensors and unless you are riding on perfectly smooth tarmac, you'll find most C5s will report the road conditions as 'rough road'.