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Will a bad Valve Block store a code ??

26K views 64 replies 11 participants last post by  doni01 
#1 ·
Reason that I am asking is that I have been recently getting a very harsh ride and no codes via Star. The car has about 100k so I am leaning on doing the front shocks but before doing that I want to make sure that the reason of the stiff ride is not the Valve Block. Any ideas ??
 
#2 ·
In the Airmatic system there are two system functions working together. The damping function or shock absorber and air spring functions. The valve block controls the amount of air in each air bladder per wheel providing mainly height adjustment. The amount of pressure in each air spring does affect ride quality, but not as much as the damping function which are electrically controlled. If the car is riding abnormally high or low the ride quality harshness will be felt.

Have you toggled your ride comfort switch to see if you can feel any difference between the comfort and sport settings? The damping system is supposed to provide feedback or store a code if internal solenoid or related part is not functioning.

Back to your question, there maybe a stored code related to the Airmatic system. When I replaced my struts I had a connector that was not seated all the way, I periodically received a "Visit Workshop" warning, then it would go away. This was due to the periodic open/close connection. Incidentally, the ride did get harsher when the connection was open. The code that was stored was C1322. Please see the screen capture.
 

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#3 ·
Thanks Rob, I have tried Raising the Airmatic and that works as it should. Now when I go and try to press the switch that stiffens the suspension and changes the settings between Convinience, Sport 1 or Sport 2 all the lights function normally BUT I do not feel any difference in the ride. Ride stays tight. In few words, even though when I am in Convinience Mode with none of the lights on, it feels like I am on Sport 2 mode. Does that make sense??
 
#4 ·
Yes, your observation makes sense... It would seem that the damping is not working, I don't have access to a STAR machine, I only have an aftermarket iCarSoft MBII scanner, this is how I found the stored code. At +100K miles, if would not hurt to replace the front struts, but understand it would be better if you had more piece of mind with a fault code. Possibly someone else may have more insight.
 
#5 ·
That's exactly where I am stuck as well. I believe it is a damping problem because I feel the tightness all around the car and not only on one particular side. Reason I ask about the Valve Body is that in my research I have read where people have experienced the same harsh ride and changing the valve has brought things back to normal. But without any codes on Star it's hard to determine. Just like you said, struts will need to be done regardless but I also want to fix the actual problem so I am not on square one :(
 
#7 ·
Thank you for chiming in Pokseva but it feels like the whole car is riding harsh therefore I didn't think that all the units could just go bad at once hence I was thinking more of the valve block going bad...But at this point it don't hurt to check all four for signs of leakage.
 
#8 ·
The air system is not involved in damping. The only way that the air system could make the ride harder would be to increase the pressure, which would visibly raise the car to the max height.

The hydraulic dampers (shocks) have computer-controlled valves inside the shocks that control oil flow, and thus make the damping softer (more oil flow thru larger orifices) or harder (less oil flow thru smaller orifices). The default failure mode is harder (a stiff ride), since the Germans always go for safety, not comfort.

Since the STAR system shows a trouble code with the right front damping valve, it appears that the car computer has put the variable damping for the entire car into failure mode - full stiff.

There are two connectors on each front side that go into a bulkhead connector at the top front of the wheel well. These can be difficult to insert properly. My suggestion is that you remove the right front wheel and support the car safely. Find the connectors - they will look like one connector. Remove the connectors, and carefully inspect both connectors and the bulkhead connector. Pair the two wire harness connectors, and insert them fully while holding them together as one unit. Make certain that they seat fully and evenly. Install the wheel and take the car for a drive to see if the ride is softer.
 
#10 · (Edited)
Thank you guys, the code that I had stored was Front Right Acceleration Sensor. We reset the code and it has never come back. Now as far as the connectors, would they just come loose on their own ?? I haven't had any work done on the car. Also will these connectors not throw any codes if they weren't inserted correctly?? Thanks again.
 
#13 ·
Doni01, my s500 is at the dealership for ride issues. I told them they could keep it as long as needed for diagnosis. Like yours, no fault codes. The tech is thinking a failed hydraulic strut within the Airmatic unit

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#14 ·
Thank you for the update John. I really appreciate it. My indy thinks also it is a bad hydraulic strut since that will not throw any codes. But he says it will be very time consuming to find it since he's gonna have to monitor all four of them via Das and see which one is acting up. Please let me know what they say. Thanks again.
 
#15 ·
I received the car yesterday morning after a week at the dealership, have driven it since then, and I can report the ride is vastly improved. Here are the services performed:
1. Another 4 wheel alignment. These w220s must be b*****s to align. The SA said it was on the rack twice to fine tune. It does drive like on rails now.
2. Recalibration of ride height. I was not aware that it was off.
3. New set of tires. The old set of Michelin Pilot Sports were nearing the end. I had them install Continental Extreme Contact DWS 06

The service tech and the foreman did not find any other issues with the Airmatic system. The foreman has been employed at the dealership over 30 years and remembers the w220 well, so I give his word credence. Was it one or two or all services that was the magic bullet? I really don't know, but I'm happy with the result. Perhaps recalibrating ride height allowed more travel in the Airmatic strut, thereby softening the ride. Doni01, I hope you are able to get to the bottom of it soon. Ask your tech to look at the above issues.
 
#17 ·
Thank you guys,
I have the same exact tires that John installed and had them put on about a year ago along with the alignment done to it. My ride has been lowered but that also was done over a year ago and I am sure it would have affected me then and not a year later. Also the fact that I can not feel a difference between Convenience, Sport 1 and Sport 2 makes me think that something has failed within the system and it is not just a tire/alignment problem. Last week after starting the car in the morning to drop the kids off at school, I started to smell something burning. Pretty sure it was my pump since it has been sounding a little rough in the last few months but has been working fine hence it has not been a suspect. Anyhow my indy has the new pump and will install it this week. If that does not fix it, I am leaning towards the valve block. So hopefully one of them will do the trick...Either way I will keep the post updated.
 
#19 · (Edited)
You are probably correct, NKJohn; and it is something many non-MB shops won't even know to do. When I was going over the VMI on my '13 W221 before buying it CPO, I noted many entries related to "adjust ride height" followed by "4-wheel alignment." They were obviously trying to troubleshoot some lingering problem. Preceding all that stuff I noted that a wheel had been replaced when the car was brand new, at 600 miles, and two tires had been replaced at unusually early intervals (7,000 and 12,000 miles). I suspected a prior owner took a curb, and the repeated followups were trying to run down the aftermath.

I asked my dealer's service manager (not the adviser - the manager) about it - he is the one who told me about the ride height/alignment relationship. It makes sense that the height can affect the geometry.

BTW - when I first drove the car, it had a slight shimmy one could feel in the steering wheel. I insisted that it be fixed before I would go ahead with the purchase (I gave them a list of 6 things that often cause shimmy, and asked for inspection results on each). The dealer found a slightly bent inner lip on one wheel (resulting in runout on one brand new tire), and having fixed that, I have had absolutely no problems. But with 20" wheels and low aspect ratio tires, even a pothole can cause such trouble.
 
#20 ·
Over the last 3 years my car had 4 alignments, 1 by a local tire shop and 3 by a MB dealership. The first, MB of K****, argued with me after the second return for poor alignment that their tech is the best in the state and it must be perfect. Nope. Then came the independent tire shop. I believe he really tried, but he could not get the camber right and was apologetic. Then came MB of C****, who did get it right the second time after checking the ride height. I do not believe MB of K**** bothered to check ride height nor particularly cared to.

Doni01, let us know how the ride feels after pump replacement.

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#21 ·
John,
You stand correct on the alignment issue. I changed the pump and the relay yesterday. Ride is still stiff...Weather has gotten significantly warmer so it's not as brutal as it was when it was cold. Still getting to the bottom of this. Will keep updating the post.
 
#23 ·
Sorry, the dealership did not provide me with the alingment numbers. The S.A. said that they removed the correction bolts that were previously installed in order to get the camber and caster correct.

The Michelin Pilot Sports that I bought 11,000 miles ago were becoming very noisy and developing a shimmy. These tires wear out around 15,000 miles, but I believe that 3 years of misalignment was hard on them. So far I really like the Continental Extreme Contact DWS 06 tires.

It drives like a different car now, the ride far less harsh and more controlled. The marriage of Airmatic suspension and the staggered, hard compound tires with the AMG appearance package seems mismatched as I do not know of software or component changes to the Airmatic system for that package. But I am pleased with how it feels now.

John

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#25 · (Edited)
Little update. I changed the valve block last night and no change. Ride continues to be stiff. Kind of disappointing since I was really hoping that was it. Oh well now I have a spare valve block. Next step will be swapping the airmatic computer. My indy has one and we are going to code it to my car and see if it's going to make a difference.
 
#26 ·
Hi,

I haven't explored coding options in Airmatic Controller yet :grin

However, I know there are tyre sizing options within other modules to apply corrections to MPG figures, Navi etc etc, so I'd get your man to see if there is a similar option within Airmatic, and also see if they are correct in the other modules, in case they affect the Airmatic via Can Comms :wink

IMHO worth a shot, unless someone can categorically refute this :wink

HTH,

Dave
 
#27 ·
You might have something, here, Dave. Sitting on the sidelines and following the repairs that have been done, I'm starting to suspect coding in the controller unit. Sonny, have you considered resetting ride height to factory specs with STAR, just for diagnostic purposes? With my car, resetting ride height (and possibly other parameters that weren't shared with me) was probably the magic bullet. Still rooting for you, man

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#29 ·
Hi,

The car has to be on a levelled 4 post lift, or tyres on 4 large equal sized wooden blocks / metal ramps, Car wheels must be standing on perfectly level surface, check tyre pressures too, otherwise your measurements will be skewed.

An inclinometer is used to measure Driveshaft angle at the rear, and lower suspension arm angle at the front, these figures must be taken from your car or the results may still be off :wink

Dean @pinkster posted an excellent article on this recently, search for it :wink

HTH

Cheers Dave
 
#35 ·
There are two damping valves on each strut. Opening a valve creates an alternate path for oil to flow through the strut and thereby reduces its resistance to motion and increases its compliance. Maximum compliance and therefore passenger ride comfort are achieved by opening both damper valves at each wheel.

Through the AIRmatic actuations menu in DAS you can manually open and close a damper valve. To test the valves at a wheel I would compare the compliance of the strut with both valves closed and with both open. The engine need not be running. I would gauge the compliance by grabbing a fender and alternately pushing down and pulling up on the fender to make the chassis bounce as much as possible. With both valves open there should be noticeably less effort, and the chassis will probably move further up and down.
 
#38 ·
Hi,

/\ /\ +1

Cheers Dave
 
#39 ·
From Post #8...

"The air system is not involved in damping. The only way that the air system could make the ride harder would be to increase the pressure, which would visibly raise the car to the max height."

"The hydraulic dampers (shocks) have computer-controlled valves inside the shocks that control oil flow, and thus make the damping softer (more oil flow thru larger orifices) or harder (less oil flow thru smaller orifices). The default failure mode is harder (a stiff ride), since the Germans always go for safety, not comfort.

Since the STAR system shows a trouble code with the right front damping valve, it appears that the car computer has put the variable damping for the entire car into failure mode - full stiff."
 
#40 · (Edited)
Hi wally,

Yes but ..........

None of that relates to the OP's car, that picture showing a fault code was from another posters car, for illustration :wink

What bobterry99 says is perfectly correct, if there is a mechanical problem with any one valve, say stuck or a piece of debris blocking it, then it may well not throw a code...........

He is saying that's why SDS asks you to actuate the valves and do the bounce test, and I agree with him, there would be no point for the test if Airmatic was monitoring valve function :wink

HTH,

Cheers Dave
 
#42 · (Edited)
Hi,

I'm pretty certain Wally was referring to a Damper Valve Code pictured on a scanner in post #2 by rob-fed :wink

I think Wally may be confusing your posts / car with rob-fed's, ref your own post #10

What bobterry99 is saying, and I agree is that you don't always get a Damper Valve Code if it is some sort of mechanical malfunction within the valve.

The Acceleration Sensor Code that you refer to will not affect your Damping if it is not an active code..........

I've seen Acc Sensor Code come up after a car has been jacked up, put on a lift etc, when I know full well it wasn't there before, as I had these cars on SDS before lifting :wink

As you have said, it doesn't come back after clearing.

Damper valves are attached to the Strut, and nothing to do with the separate Airmatic VB above the Compressor. Think of it like this, Airmatic is your spring and ride height system, Damping is separate :wink

You would regard a Regular Car Coil Spring and Shock Absorber as separate systems :wink

Cheers Dave
 
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