Resonanceintake switchover valve

[JOHNO978]

Hi guys,Not been on here for quite some time due to health matters.I have been browsing for the past week or so as I have just put my C280 back on the road after 2 years.I have done all the work myself apart from the diagnostics needed to reset the ECU`s after installing new ABS/Speed sensors and the OVP relay.I was having an issue with "Surging" all the time so decided to clean out the MAF and the Throttle body, All went fairly easy untill I started the car, the idle speed is now leveling out at 1500 steady.I have no leaks at the throttle body nor at the Intake manifold switchover valve, all the vacuum hoses that came off during the job are back on and ok (I put bright yellow insulating tape on them so I could find them easily)...electrical connectors are all back on (Red tape on these). However I did notice that on the underside of the of the Intake manifold switchover valve there is a stubby hose,inside of this is a very small mesh insert...I removed the valve again and sucked on the little tube and the butterfly ? rotated a half turn as if it would allow airflow to pass it.I am wondering if there should be a vac hose on this ? I can only assume if there should it came off when I was taking it apart...but I cant for the life of me find it...any help would be fantastic as Ive no Idea where to look next or what the hose ( if there is one) would come from.I will try to post a diagrame that I have if that would help.
Regards
Steve.....

 

[JOHNO978]

Oh Dear, 187 views and no suggestions, Seems that this problem has never arisen before,When I solve it I shall post how I did it to help anyone else who comes across it...its certainly testing my brain thats for sure...
Steve.

 

[grober]

this help? [ gn=green tr =transparent ] colour code missed on diagram.
available here MBUSA Technical Training

 

[JOHNO978]

Thanks Graeme, All the vac hoses shown that are relevant are conected in the right places....maybe Im looking for something that isnt there...lol...Im puting new Gaskets on the Throttle body and the Intake Manifold Switchover Valve...Ive got them from Mercedes in Southport who had them shipped over from Germany...so I will see how it goes after that little job is done..if its still the same...Diagnostics is the only way forward I think...Thanks once again Regards,
Steve.

 

[grober]

Only other thing I can suggest is putting some sort of blanking sleeve over the connection to see what does to the idle?

 

[JOHNO978]

I tried that with my finger whilst the engine was running and it made no difference...I ve found a length of pipe that I think will fit..so Im going to atatch it to the "Valve" and suck on it when the engine is running and see if that sorts the Idle out...if it does..I will have to get the car up on high ramps and have a real good look for this possible elusive pipe...
regards
Steve.

 

[JOHNO978]

...The little stub at the top of the picture..just below the contact pins...is where I think a vac hose could be attatched...Im not sure...any thoughts chaps,
Steve

 

[grober]

Looks very like a vacuum connection. Have you got the vacuum connection from the pressure regulator at the end of the fuel rail connected up/

 

[JOHNO978]

Im sure I have all vac lines connected Graeme....Ive checked and double checked..My second gasket should arrive tomorrow so I shall be stripping everything out again to fit the 2 new ones...while the parts are out it is a lot easier to see whats what and I shall be going over everything with a fine tooth comb...but before I strip anything I shall attatch a hose to the stub in the picture and suck on it to replicate some vacuum...then see what happens...whatever the outcome of that little test I shall still replace the 2 gaskets...sorry for the delay in responding..I couldnt access your response for some reason,
Regards,
Steve.

 

[JOHNO978]

Hi Graeme,Im sure all the vac lines are connected...I shall double check again when I fit the 2 new gaskets that I have had sent from Germany...I shall also fit a hose to the stub and when the engine is running I will suck on it to create a vacuum and see if that changes things...if it does then Ive left a hose off somewhere !!!
Regards,
Steve

 

[JOHNO978]

Im sure I have all vac lines connected Graeme....Ive checked and double checked..My second gasket should arrive tomorrow so I shall be stripping everything out again to fit the 2 new ones...while the parts are out it is a lot easier to see whats what and I shall be going over everything with a fine tooth comb...but before I strip anything I shall attatch a hose to the stub in the picture and suck on it to replicate some vacuum...then see what happens...whatever the outcome of that little test I shall still replace the 2 gaskets...sorry for the delay in responding..I couldnt access your response for some reason,
Regards,
Steve.

Im having great difficulty acsessing my post for some reason...anyhow..I fitted the 2 new gaskets but the problem is still there...I did however push down on the throttle linkeage at the side of the intake manifold and the revs dropped.to 600rpm on Idle...so a good clean up of this linkeage is now on the cards...it will be easier if I remove the washer bottle for better acsess....

 

[JOHNO978]

Resonance Intake Switch over Valve

The problem is now solved...there isnt a Vac tube thats atattched to the stub at the base of the valve...I took my car into Mercedes in Southport after discussions via email, it seems that once the Throttle body has been disconected it needs the Idle speed to be re-set by dedicated Diagnostics...whilst doing this they found that the o2 sensor was holding a code caused by the disconection...once this code was cleared and the Idle speed re-set the car ran like a dream...all problems soved. They gave the car a full Diagnostic check over and everything is just fine...the cost of this was just £65 incl Vat...for me its money well spent and I wish I had gone there in the first place...it would have saved me lots of time...Ive been dealing with Mercedes in Southport since I started to put my car back on the road and can only say what a big help they have been giving me advice...and not only to sell me parts....Thanks to those of you who have helped me with this problem over the past few weeks...especially Grober...cheers.
Regards,
Steve.:bannana: