Objective Test of EDC performance

[Tony B]

Is there an objective test for EDC damper performance?

I have recently felt that my CP car is rather less capable and controlled on undulating/rough surfaces, than it used to be.

As the EDC system is adaptive, closed-loop (so adjusting dampers in real time, according to wheel deflection and speed of movement) I assume that this means the system can adjust itself to cope with declining damper/valve efficiency?

If this is so, presumably at some point in the wear process it will run out of capacity to compensate?

I have a full BMW warranty still on my car, but have to pay £100 for any diagnostics, which is refundable if a fault is found. However, I am not keen on sending out a tech to road test the car, when he has probably not touched another E9x M3 in the last 3 years so has nothing to compare against, subjectively.

So, is there a repeatable/reliable test for damper efficiency?

The car has 46k miles on the clock, but has had almost the entire suspension refreshed, front and rear, apart from dampers, in the last 5k miles. No rattles or knocking sounds are apparent on bumps.

[wyatth]

I’m with ya, noticing slight degradation over time. I’m at 60K and it feels a little more crashy over bad terrain than it did when I got the car at 45K. The shocks are definitely okay but … aging, as expected.
I have not heard of objective tests, best to start looking ahead to replacements or rebuilding them.

[Z K]

It's normal shock degradation over time. Most shocks need a rebuild/replacement by 60k miles. Less if you have very rough roads.

I very much doubt BMW has a way to test shock degradation and no way is that covered by warranty. This is normal wear and tear.

EDC is just adjustable dampening. It is a pretty primitive system that turns it up and down - same as on a manually adjustable dampener. It is only "closed loop" in that it knows if it can turn the shock up or down otherwise it will throw an error code. It has no way of "sensing" a shock's dampening. Some newer cars that have magnetic dampening may be able to tell, but that's not this. The technology in these shocks are over 15 years old now - don't expect much.

[Tony B]

Originally Posted by Z K

It's normal shock degradation over time. Most shocks need a rebuild/replacement by 60k miles. Less if you have very rough roads.

I very much doubt BMW has a way to test shock degradation and no way is that covered by warranty. This is normal wear and tear.

EDC is just adjustable dampening. It is a pretty primitive system that turns it up and down - same as on a manually adjustable dampener. It is only "closed loop" in that it knows if it can turn the shock up or down otherwise it will throw an error code. It has no way of "sensing" a shock's dampening. Some newer cars that have magnetic dampening may be able to tell, but that's not this. The technology in these shocks are over 15 years old now - don't expect much.

Well, I am in the UK - so we have rough roads!

My BMW (Comprehensive) warranty does cover wear and tear, shock absorbers, bushings, etc, so I have no doubt that there will be a need to prove a certain level of degradation before I can make a claim.

Regarding the “closed-loop” part, I was given a pre-launch ride in the E92 on the Nurburgring in 2007, by the then head of BMW Driver Training. He definitely said of that car that the damping was adaptive in Comfort and Normal, and the system could continuously alter the damping, based on suspension deflection, and rate (speed) of movement, within a single cycle. He said that this meant, for example, whilst in Normal mode the damping could actually go as far as the Sport rate, momentarily, if required.

The 3 modes determined the mid-point of each damping rate.

I might have this conversation on video, because I definitely had my camcorder with me on the ride. I will try to dig it out.

Also, this capability would be consistent with the Competition Pack changes, where Sport was billed as becoming adaptive, as well as Comfort/Normal, rather than fixed rate.

I am going to dig a bit on this, as well as check the “objective test” thing with a contact I have at a dealer.

[Tony B]

LOL at myself - I had forgotten about this, from a 2012 discussion on a UK forum
LOL - because I had forgotten that I was involved.
Never mind damper degradation, my brain….

Not sure who MPW is. Philipp Waenninger is the chassis engineer responsible for the M3 CP.

*********************************************
MPW: Mr. Wänninger, what is meant by EDC?

Wänninger: EDC stands for Electronic Damping Control. EDC offers the customer the choice between a number of different damping maps. Even in the BMW M3 E30 it was possible to choose between Comfort, Normal and Sport by means of a switch. In the current BMW M3 the principle was taken a step further: here the damping is not fixed at a set level in Comfort and Normal mode but is regulated to achieve an optimum level depending on the actual driving situation.


Philipp Wänninger

MPW: How does this regulation work?

Wänninger: The current driving situation is determined by means of numerous sensors. Three acceleration sensors measure the movement of the vehicle along the road. If a steering movement is made, there is an immediate impact on damping - and the same applies to acceleration and braking, too.

MPW: How is the damping influenced?

Wänninger: It is mainly the rebound which is adjusted by controlling the damper piston valve.

MPW: How is the EDC in the Competition Package different from that in the serial production vehicle?

Wänninger: In the BMW M3 Competition Package damping in the Sport mode is now regulated too - in the serial production model it is based on a fixed level.

[I/I]

[Z K]

Originally Posted by Tony B

Well, I am in the UK - so we have rough roads!

My BMW (Comprehensive) warranty does cover wear and tear, shock absorbers, bushings, etc, so I have no doubt that there will be a need to prove a certain level of degradation before I can make a claim.

Regarding the “closed-loop” part, I was given a pre-launch ride in the E92 on the Nurburgring in 2007, by the then head of BMW Driver Training. He definitely said of that car that the damping was adaptive in Comfort and Normal, and the system could continuously alter the damping, based on suspension deflection, and rate (speed) of movement, within a single cycle. He said that this meant, for example, whilst in Normal mode the damping could actually go as far as the Sport rate, momentarily, if required.

The 3 modes determined the mid-point of each damping rate.

I might have this conversation on video, because I definitely had my camcorder with me on the ride. I will try to dig it out.

Also, this capability would be consistent with the Competition Pack changes, where Sport was billed as becoming adaptive, as well as Comfort/Normal, rather than fixed rate.

I am going to dig a bit on this, as well as check the “objective test” thing with a contact I have at a dealer.

Yes, the EDC is variable based on the mode it is set to. But this is not based on feedback from the dampener itself - it is based on how you are driving. Your quotes verify this as well:

Three acceleration sensors measure the movement of the vehicle along the road. If a steering movement is made, there is an immediate impact on damping

I.E. if you are driving fast and steering quickly, it will firm up the suspension. If you are driving straight at a slow speed, it will turn the dampening down. It is very primitive compared to magnetic suspension now.

There is no way for the car to know the condition of the dampener and adjust itself. You are expecting too much from EDC.

Most people who care about handling have it disabled and replace the EDC shocks with high performance suspension more appropriate for the M3. EDC shocks are complete shit for any kind of performance driving.

[Tony B]

This description is open to interpretation:

The current driving situation is determined by means of numerous sensors. Three acceleration sensors measure....

"Numerous" does not necessarily mean "three".

As I know Phillip W quite well, I have emailed him to ask for clarification.

I am sure he will remember 12 years ago when the Comp Pack was introduced.

If he responds, I will let you know...

[derbo]

Originally Posted by Tony B

This description is open to interpretation:

The current driving situation is determined by means of numerous sensors. Three acceleration sensors measure....

"Numerous" does not necessarily mean "three".

As I know Phillip W quite well, I have emailed him to ask for clarification.

I am sure he will remember 12 years ago when the Comp Pack was introduced.

If he responds, I will let you know...

There is 3 sensors for vertical acceleration.

Two vertical acceleration sensors in the front wheel arches, and 1 rear right hand arch.

It also uses the steering angle sensor and wheel speeds from speed sensors to determine the programming.

These "numerous" sensors is what is evaluated in the EDC Module.

[Z K]

Originally Posted by Tony B

This description is open to interpretation:

The current driving situation is determined by means of numerous sensors. Three acceleration sensors measure....

"Numerous" does not necessarily mean "three".

As I know Phillip W quite well, I have emailed him to ask for clarification.

I am sure he will remember 12 years ago when the Comp Pack was introduced.

If he responds, I will let you know...

I don't understand what you are getting at.

While it is looking at these sensors to determine the dampening setting, this is hardly the kind of "closed loop" you are looking for for shock condition and feedback from the shock itself. There are no sensors in the shock and it does not provide feedback to EDC. So this does not relate to your original question.

[Tony B]

Originally Posted by Z K

I don't understand what you are getting at.

While it is looking at these sensors to determine the dampening setting, this is hardly the kind of "closed loop" you are looking for for shock condition and feedback from the shock itself. There are no sensors in the shock and it does not provide feedback to EDC. So this does not relate to your original question.

If there are 2 vertical sensors in the front arches and 1 in the rear, the system does not need any sensors in the dampers themselves to determine suspension deflection or rate of change.

As each EDC mode has its own map it should be possible - in theory - to determine whether current performance aligns to the pre-programmed map and thereby either:

1. Determine whether wear has degraded performance - my original question "is there an objective test"

And/or

2. Adjust damper settings to compensate for wear

I will see what Philipp says, if he has time to respond. I have met him several times, and I am sure he will if he has time.

[Z K]

Originally Posted by Tony B

If there are 2 vertical sensors in the front arches and 1 in the rear, the system does not need any sensors in the dampers themselves to determine suspension deflection or rate of change.

As each EDC mode has its own map it should be possible - in theory - to determine whether current performance aligns to the pre-programmed map and thereby either:

1. Determine whether wear has degraded performance - my original question "is there an objective test"

And/or

2. Adjust damper settings to compensate for wear

I will see what Philipp says, if he has time to respond. I have met him several times, and I am sure he will if he has time.

This is way too much work for what you are trying to achieve. EDC on my car has been disabled and replaced for over 12 years since when I purchased the car. It was a crap system when it was new and much worse by today's standards.

Your #2 is not doable, and even if it is, the adjustment does not affect rebound, the EDC shock adjustment is just dampening (bound) so "compensating" by turning up the dampener will only change 1 aspect of the shock.

EDC is bad. Only dampening adjustment, no rebound, lack of suspension travel because of BMW's bad design choices and it's expensive. The adjustment is basically between soft and comfortable to very uncomfortable with no improvement in performance.

[wyatth]

^ I reckon factory EDC shocks adjust both compression and rebound, while aftermarket options (eg Bilstein) only adjust rebound. I've also never heard of travel issues unless paired with lowering springs, which is no fault of the dampers.

Yes EDC is relatively primitive and does not transform the car from a Camry to a GT3. But for many people it's still a nice option with noticeable differences in comfort and performance between the modes. Is it the best option, especially for those that track regularly? Absolutely not. But many have it and are happy with it on real world roads. TBD what I do when my ZCP shocks go.

[Tommysalami]

I'll be dynoing some old EDC shocks eventually. We'll see how the graphs look.

Any idea if EDC is just feeding a 12v signal to the shock to change damping?

[wyatth]

I'm also curious if EDC shocks can be rebuilt, might contact PSI in Sonoma. Could be a better option than Bilsteins or new OE for those of us that want to refresh EDC.

[Tony B]

Originally Posted by wyatth

^ I reckon factory EDC shocks adjust both compression and rebound, while aftermarket options (eg Bilstein) only adjust rebound. I've also never heard of travel issues unless paired with lowering springs, which is no fault of the dampers.

Yes EDC is relatively primitive and does not transform the car from a Camry to a GT3. But for many people it's still a nice option with noticeable differences in comfort and performance between the modes. Is it the best option, especially for those that track regularly? Absolutely not. But many have it and are happy with it on real world roads. TBD what I do when my ZCP shocks go.

This is interesting - can you tell me which document this comes from?

[wyatth]

I cannot find the primary source right but my understanding is that it comes from an official BMW technical bulletin/PDF.

[bmw>benz]

Originally Posted by Z K

This is way too much work for what you are trying to achieve. EDC on my car has been disabled and replaced for over 12 years since when I purchased the car. It was a crap system when it was new and much worse by today's standards.

Your #2 is not doable, and even if it is, the adjustment does not affect rebound, the EDC shock adjustment is just dampening (bound) so "compensating" by turning up the dampener will only change 1 aspect of the shock.

EDC is bad. Only dampening adjustment, no rebound, lack of suspension travel because of BMW's bad design choices and it's expensive. The adjustment is basically between soft and comfortable to very uncomfortable with no improvement in performance.

Originally Posted by Z K

This is way too much work for what you are trying to achieve. EDC on my car has been disabled and replaced for over 12 years since when I purchased the car. It was a crap system when it was new and much worse by today's standards.

Your #2 is not doable, and even if it is, the adjustment does not affect rebound, the EDC shock adjustment is just dampening (bound) so "compensating" by turning up the dampener will only change 1 aspect of the shock.

EDC is bad. Only dampening adjustment, no rebound, lack of suspension travel because of BMW's bad design choices and it's expensive. The adjustment is basically between soft and comfortable to very uncomfortable with no improvement in performance.

Wrong. Everywhere

[derbo]

Originally Posted by Tony B

This is interesting - can you tell me which document this comes from?

It comes from the official bmw technical training document.

https://www.e46fanatics.com/d1/pdf/B...nformation.pdf

[Tony B]

Originally Posted by derbo

It comes from the official bmw technical training document.

https://www.e46fanatics.com/d1/pdf/B...nformation.pdf

This is a really interesting document, so thanks for sharing.

The EDC-K section also mentions more information being available in E65 documentation.

I am on the case....;-)

[derbo]

Originally Posted by Tony B

This is a really interesting document, so thanks for sharing.

The EDC-K section also mentions more information being available in E65 documentation.

I am on the case....;-)

Yeah E65 7 series was the first to introduce EDK of this generation. It was definitely geared towards comfort more than anything.

https://archive.org/details/BMWTechn...ningDocuments/

Might be able to find it here.

[Tony B]

Originally Posted by derbo

Yeah E65 7 series was the first to introduce EDK of this generation. It was definitely geared towards comfort more than anything.

https://archive.org/details/BMWTechn...ningDocuments/

Might be able to find it here.

Many thanks!

A bit of reading confirms my second question - can EDC adapt to compensate for wear?

The answer is "yes"...from page 20 of "E65 Driving Dynamics Systems"

Tolerance Adaptation
The damper force is diminished as part of the operating time function. Diminishing damper forces are compensated by current (amperage) reductions which are calculated by the tolerance control. This also individually compensates for mechanical damper wear on each axle.

And from page 23

Mechanical wear causes the dampers to weaken over the service life, therefore a running time memory adapts the damper curves towards a harder setting (over time). Faulty dampers must be replaced together (in pairs) on a single axle. After a replacement, the running time memory for the front or rear axle must be reset with the DISplus.

Other text within the same document confirm the system continuously monitors damper piston speed and adjusts damping force to align to defined maps.

= Closed loop

Acceleration sensors record the driving/road surface conditions and the control module receives the sensor frequency signals for evaluation. The sensor signals are compared with each other for plausibility. The control module logic activates the damper valves according to internal programmed maps to dampen body and wheel movement as needed.


So..."someone" in this thread needs to wind his neck in....

[Tommysalami]

Originally Posted by Tony B

Many thanks!

A bit of reading confirms my second question - can EDC adapt to compensate for wear?

The answer is "yes"...from page 20 of "E65 Driving Dynamics Systems"

Tolerance Adaptation
The damper force is diminished as part of the operating time function. Diminishing damper forces are compensated by current (amperage) reductions which are calculated by the tolerance control. This also individually compensates for mechanical damper wear on each axle.

And from page 23

Mechanical wear causes the dampers to weaken over the service life, therefore a running time memory adapts the damper curves towards a harder setting (over time). Faulty dampers must be replaced together (in pairs) on a single axle. After a replacement, the running time memory for the front or rear axle must be reset with the DISplus.

Other text within the same document confirm the system continuously monitors damper piston speed and adjusts damping force to align to defined maps.

= Closed loop

Acceleration sensors record the driving/road surface conditions and the control module receives the sensor frequency signals for evaluation. The sensor signals are compared with each other for plausibility. The control module logic activates the damper valves according to internal programmed maps to dampen body and wheel movement as needed.


So..."someone" in this thread needs to wind his neck in....

How do you do this? I replaced my rear shocks with Bilstein EDC dampers and feel like it's too stiff, maybe something to do with this