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Discussion Starter · #244 ·
More on Actual Values from latest diagnostics ...

Signals 1 & 2 for Front L & R sensors all within specified values (2.30 to 2.70).

But for rear axle level sensor (B22/3):

Signal 1: 2.18 (specified value 2.30 to 2.70)
Signal 2: 2.84 (specified value 2.30 to 2.70)

He explained that although slightly out of range, the differing values should compensate for each other.

Any thoughts..? Many thanks all.
 

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If sensor reading is 'outside' range, shouldn't system try to correct it back to calibrated values? Has calibration done (succesfully!), to which values? Both rears are too high (or too low), readings L/R go opposite direction...
 

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Discussion Starter · #246 ·
If sensor reading is 'outside' range, shouldn't system try to correct it back to calibrated values? Has calibration done (succesfully!), to which values? Both rears are too high (or too low), readings L/R go opposite direction...
Thanks mersum, I don't know but maybe someone else here can explain how it works? My Techie said 'no faults stored' so I assume it doesn't need calibrating? But again, I'm not an expert in these things. All I do know is that the damping is still quite hard. It's a real mystery! ;)
 

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You can calibrate the riding height. Then system tries to maintain it. Control is quite robust, filtered heavily (slow), and not very accurate. But calibration set value must be inside certain sensor range (probably same than you refer in your garage report, in order to accept calibration values. (Well, in developer mode you can fool the system slightly). Now it would be nice to remake the calibration, and see what happens. Also see if sensor readings do change rationally when struts are driven up/down etc.

Like discussed before, damping should not be affected by height is ride height is normal. But because sensor readings are out of range, it could indicate something...
 

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"Not being hampered by facts, I can discuss the matter freely." Cecil Stockard, Sr.

"But for rear axle level sensor (B22/3):

Signal 1: 2.18 (specified value 2.30 to 2.70)
Signal 2: 2.84 (specified value 2.30 to 2.70)

He explained that although slightly out of range, the differing values should compensate for each other."


Fact: There is one height sensor for the rear suspension.

Facts (?); There are two simultaneous signals sent from the rear height sensor. (?) Neither signal is within programmed limits. (?)

Question: Does the control computer actually average the two sensor readings and use that average value as the height signal?
Or does the control computer say, "I have no idea what the height is on the rear suspension, so I am going to the fail-safe status."?

I don't have a clue whether either situation is reality...

How much does a height sensor cost?
 

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Discussion Starter · #249 ·
"Not being hampered by facts, I can discuss the matter freely." Cecil Stockard, Sr.

"But for rear axle level sensor (B22/3):

Signal 1: 2.18 (specified value 2.30 to 2.70)
Signal 2: 2.84 (specified value 2.30 to 2.70)

He explained that although slightly out of range, the differing values should compensate for each other."


Fact: There is one height sensor for the rear suspension.

Facts (?); There are two simultaneous signals sent from the rear height sensor. (?) Neither signal is within programmed limits. (?)

Question: Does the control computer actually average the two sensor readings and use that average value as the height signal?
Or does the control computer say, "I have no idea what the height is on the rear suspension, so I am going to the fail-safe status."?

I don't have a clue whether either situation is reality...

How much does a height sensor cost?
Good question(s) wally - maybe Dave2302 will know the answer. It did occur to me to fit a new rear height sensor just in case (I've replaced just about everything else!). I don't think they are expensive in the big scheme of things.

And I seem to remember the techie saying if I fit a new sensor the system will need to be re-calibrated anyway.
 

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Does the control computer actually average the two sensor readings and use that average value as the height signal?
Yes that is exactly how it works ;) ...................

Therefore, technically it is within spec, probably wouldn't hurt to change it and see what happens, may not need to Calibrate as the wee metal arm is adjustable :unsure:
 
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Discussion Starter · #251 · (Edited)
A Further Question (to annoy you all again - ha ha 😜)..

Given that I've noticed a slight, momentary, intermittent and randomly occurring but NOTICEABLE 'softening' of the hard damping at one, maybe two struts after the latest SDS (apparently they physically 'tweaked' some of the sensors whilst on the ramp and then mentioned the slight discrepancy in the rear axle level sensor values after lowering the car / driving it):

Is it possible that just ONE Airmatic / ADS sensor and / or its mechanical linkage might be causing it to randomly / momentarily go outside of specified values and 'fool' the ECU into thinking 'all's normal' with the entire ADS system? But (again) WITHOUT registering a Fault - due to its random / momentary nature (e.g. for a few milliseconds only?). Only my amateur Logic...

So: might the Hard Damping fault be only Movement (e.g. Road-jolt?) related perhaps, as opposed to when the car is tested stationary (hence 'no faults stored')? I've had a hunch about this all along. And, if you remember, a BIG Clue was that momentary 'burning-rubber' smell inside the cabin when I first had the car. Still a Mystery, but it suggests an electrical / wiring issue somewhere in the Airmatic / ADS set-up maybe? You tell me (all the other electrics work ok).

As Janis Joplin (RIP) said in her famous last song: "Oh Lord, won't you buy me a Mercedes Benz?" Little did she know - and probably for the best? ;)

Either way: best wishes all, stay Covid Safe and enjoy your Weekend. Thanks for your continued input (and patience) in the meantime.

MB :)
 

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Definitely plausible, which is what you want a SDS to plug in the car while driving to replicate.

Perhaps one of the acceleration sensor.
 

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Discussion Starter · #253 ·
Definitely plausible, which is what you want a SDS to plug in the car while driving to replicate.

Perhaps one of the acceleration sensor.
Thanks Deplore, that's helpful to know. (y)

Best wishes from the UK
 

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Hi Mark,
Deplore is right. It is worth driving around and having the car hooked up to an SDS watching the values. I did that when I had my issue but everything checked out in my case and it didn't help but in yours it might. Just bring it up with your mechanic and see what he says...
 

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Discussion Starter · #255 ·
Hi Mark,
Deplore is right. It is worth driving around and having the car hooked up to an SDS watching the values. I did that when I had my issue but everything checked out in my case and it didn't help but in yours it might. Just bring it up with your mechanic and see what he says...
Thanks Sonny, you and Deplore are probably right. I did ask them to do 'on the move' / streamed data: but to be honest I'm not sure if they did that in the end (probably too much time and labour involved if they are trying to save me costs?) The price for 2 Hours' inspection / SDS was only £140 GBP so I'm not unhappy about that. And it's been HOT HOT HOT here: so maybe I wasn't 'on their backs' (supervising them) enough for the same reasons? :ROFLMAO:

That said: this local Indie seems to be helpful and interested / open minded overall (and importantly has agreed that the Ride is 'a bit too firm'). So next time I will ask them to do the 'Drive / Record Streamed / Dynamic Data' / Report back etc in conjunction with physically inspecting and 'tweaking' the various sensors and / or replacing them as necessary. As Dave 2302 says: replacing a couple of (possibly faulty but not showing on SDS for some reason) sensors might fix the problem and at relatively low cost after all the major costs (4 new struts etc). We'll see...

Isn't it weird when the Customer / Client needs to guide the 'Expert' in resolving a problem?! But I've known this phenomenon in other contexts too (e.g. Health / Legal issues etc).

I'm away next week but will pick up the threads when I get home. As always, sincere thanks and To Be Continued..(y);)
 

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Yep, like stated before, 'rock hard erected up' car can be result of viag.... no but failed accelerator sensor. BUT that should trigger a code, or seen in live data. And ADS wires are prone to fail. I just can't remember if open circuit means hard setting (AND IMO ADS should never go rock hard even at most sporting setting - why acc sensor fault is having hard suspesion is becuse struts are driven at upper ends).

MB's are 'Sonderklasse', thats why 'regular' mechanics won't do... :)
 

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Discussion Starter · #257 ·
Yep, like stated before, 'rock hard erected up' car can be result of viag.... no but failed accelerator sensor. BUT that should trigger a code, or seen in live data. And ADS wires are prone to fail. I just can't remember if open circuit means hard setting (AND IMO ADS should never go rock hard even at most sporting setting - why acc sensor fault is having hard suspesion is becuse struts are driven at upper ends).

MB's are 'Sonderklasse', thats why 'regular' mechanics won't do... :)
Ha ha - Mercedes 'S' Viagra! :ROFLMAO:. You Finnish people have a great sense of humour :ROFLMAO: (In fact I have visited Finland on business and the Finns are lovely people) (y);)

I think you, Dave, doni, wally and Deplore could be right: i.e. maybe a front sensor (acceleration?) momentarily failing (but NOT talking to the ECU for some reason ?).

You also have good point about ADS wires failing somewhere in the circuit. This COULD explain the 'burning' smell way back, but again NOT registering any fault codes.

Hey ho, thanks for your ideas as always ;)
 

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At this point you might need to go OEM route and do what engineers do.... Get 8 channel oscilloscope, probe all four acceleration sensors and graph them and compare to what SDS is outputting.

Or start measuring wire resistance from all accelerator and level sensors to the airmatic module, . Should be less than 3ohm, cold or hot.
 

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Discussion Starter · #259 ·
At this point you might need to go OEM route and do what engineers do.... Get 8 channel oscilloscope, probe all four acceleration sensors and graph them and compare to what SDS is outputting.

Or start measuring wire resistance from all accelerator and level sensors to the airmatic module, . Should be less than 3ohm, cold or hot.
Thanks Deplore, that's VERY helpful!(y).

As mersum suggested: 'S' (Sonderclass) airmatic / ADS electrical problems are sometimes too complex for 'regular' Techies (even Mercedes Techies using SDS?). I'll pass your advice on to my local Techie (or a skilled auto electrician). Will update later in case it helps others here.

Thanks as always for your and others' advice & support here. AND (as important) for taking me seriously in my reports / description of this long term problem. I really appreciate it ;)

Best wishes from the UK

MB
 
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