my reading of the below - I was expecting more of a comfortable driving experience over bumpy roads




this is the bit that caught my eye

"To maintain wheel travel, the rear dampers feature an additional external accumulator.
This is to provide adequate rebound travel by recovering the volume through the external source"


How would it be possible to test if one of both of these external accumulators is working as intended ( or not ) ??

Last edited by pcourtney on 20th Apr 2023 8:21pm. Edited 1 time in total

That explains how the dampers go from firm to soft but not how the ECU decides when to set the dampers to firm or soft. Early RR drivers no doubt expected a soft ride with relaxed handling but the market shifted to customers who wanted a firmer more responsive ride and this may be the compromise we have now. I still can't see how a system like this can at once detect a sudden jolt from an imperfection in the road surface and open the shock absorber valve quickly enough to prevent it causing that motion to be transferred to the body. 2012 TDV8 Vogue (L322)

pcourtney wrote:

How would it be possible to test if one of both of these external accumulators is working as intended ( or not ) ??

JayGee wrote:

I still can't see how a system like this can at once detect a sudden jolt from an imperfection in the road surface and open the shock absorber valve quickly enough to prevent it causing that motion to be transferred to the body.

Electricity travels at roughly 90% of the speed of light, easily fast enough for the dampers to adjust in real time to suit the road conditions...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

The ECU still has to receive and process the signals from the accelerometers and height sensors and then the valve has to open which is a mechanical device. Unless there was a sensor system that read the road infront of the vehicle to soften the dampers ready for an impact I can't see how this can work to iron out these kinds of jolts. 2012 TDV8 Vogue (L322)

I recall reading that Mercedes scan the road so that the shocks can be prep'd for the bump, rather than wait for the sharp wheel movement when its a bit late.

Maybe it responds to the pothole by tightening up and preventing bounce once you have driven over it...

It could be smoke and mirrors as well....

Whatever it does the two 2010-12 ones I have had ride bumps, potholes and traffic calming much better than the earlier ones and body roll on corners is massively reduced, at no point would I call it hard....

Tyres and tyre pressures have a massive impact on ride, my wifes Lexus came with new runflats, they went in the skip within days, it was as if it didn't have suspension... "Normal" tyres and it's fine... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Mine's much better now. I had been running on -12mm via the GAP IID tool and reset it to standard and it suddenly got a lot better. Doubt a 12mm change in itself made a difference but it may well have reset something? 2012 TDV8 Vogue (L322)

I have noticed that my car has also gotten quite hard at the rear end and I have metered out the dampers for PWM directly by interfacing my multimeter with the damper wiring. I set the meter up for data logging and got some direct data from the drive around the block.

When out for a drive the duty cycle varies between 0-35% which in reality is rock hard to slightly less rock hard. It looks like the CVD module output from the sensor data is inverted.

The damper duty cycle at 100% would be classified as soft.

The IID tool shows the damper status as soft in the live data but the damper itself would suggest this is actually the opposite.

I have tested all the height sensors and yaw sensors and they are all spot on within tolerance and the dampers themselves are all perfectly functional. I have a replacement CVD module on the way and I'll see what the system does when I swap out the units. Christian.


Current Cars
2011 Range Rover Vogue SE
2020 BMW M4 Competition
2019 BMW X4

My RR Blog: www.facebook.com/L322Project
or
https://www.fullfatrr.com/forum/topic61540.html

Graeme wrote this back in Nov 2017 - which caught my eye


My 1st recalibration was done whilst not moving so the CVD's were set uselessly soft.

The next was done whilst driving over very rough off-road conditions causing them to be set too firm .

The current calibration was done on very slightly rough secondary sealed road

The next one will be done at 80-100 kph on my not so smooth gravel lane.

NB Recalibration is done for a 10 second (or thereabouts) period.

===========

so if some of us are having harsh ride conditions in our late L322's ( CVD was standard on MY11 and MY12 cars) , then it might be worth recalibrating the CVD modules when the car is stationary - and see if the ride becomes more compliant after doing that

I calibrated mine whilst stationary and they are still race car hard so I'm not sure that has any relevance to the fault I am seeing.

BTW See you are in Stortford, I'm about 2 mins from there  Christian.


Current Cars
2011 Range Rover Vogue SE
2020 BMW M4 Competition
2019 BMW X4

My RR Blog: www.facebook.com/L322Project
or
https://www.fullfatrr.com/forum/topic61540.html

Logically such a system would self calibrate over time to account for long term changes like wear in shock absorbers and short term changes like load changes i.e when the vehicle is fully loaded and when it's not. 2012 TDV8 Vogue (L322)

JayGee wrote:

Mine's much better now. I had been running on -12mm via the GAP IID tool and reset it to standard and it suddenly got a lot better. Doubt a 12mm change in itself made a difference but it may well have reset something?

pcourtney wrote:

Graeme wrote this back in Nov 2017 - which caught my eye


My 1st recalibration was done whilst not moving so the CVD's were set uselessly soft.

The next was done whilst driving over very rough off-road conditions causing them to be set too firm .

The current calibration was done on very slightly rough secondary sealed road

The next one will be done at 80-100 kph on my not so smooth gravel lane.

NB Recalibration is done for a 10 second (or thereabouts) period.

===========

so if some of us are having harsh ride conditions in our late L322's ( CVD was standard on MY11 and MY12 cars) , then it might be worth recalibrating the CVD modules when the car is stationary - and see if the ride becomes more compliant after doing that

Caesium wrote:

I have tested all the height sensors and yaw sensors and they are all spot on within tolerance and the dampers themselves are all perfectly functional. I have a replacement CVD module on the way and I'll see what the system does when I swap out the units.