Resonance valve switch

[kropsch]

I recently bought a '97 C280. I just found that the Resonance valve switch was broken. I put a new one in place connecting the electrical plug, but could not find where to connect the vacuum.
I believe the previous owner lost the vacuum hose. Can someone
tell me where and how is the vacuum connected. Is there a way to check if the electrical plug is receiving current when the valve opened ?

[Pagz]

Welcome:)
...Im not sure what a resonance Valve switch is?,are you talking about the solinoid that resides infront of you windsceen washer bottle?

Rgrds,
Paul

[jnenad16]

I think he is refering to the variable intake manifold flap(switchover valve). as for the vacuum, it should be connected to the intake manifold so that the flap can adjust according to the manifold pressure.

nenad

[Pagz]

Originally posted by jnenad16
I think he is refering to the variable intake manifold flap(switchover valve). as for the vacuum, it should be connected to the intake manifold so that the flap can adjust according to the manifold pressure.

nenad

Hmmm,Is it there to minimise noise,or is to change intake design for a better torque curve??

Paul

[kropsch]

It is there to minimize noise modifying the length of the intake manifold avoiding resonance.
Does someone have instructions about installation and test of this part ?

[Pagz]

Hmmm,varying the length must also do well for the torque curve,anyhow sorry cant help...

Paul

[jnenad16]

Originally posted by 23K
Hmmm,Is it there to minimise noise,or is to change intake design for a better torque curve??

Paul
its there to improve the torque in the lower rpm's by lenghtening the intake and increase HP in the higher rpm's by shortening the intake. the part that is used to minimize the noise is the resonator and its connected to the throttle body boot.

nenad

[benzfan]

Originally posted by jnenad16
I think he is refering to the variable intake manifold flap(switchover valve). as for the vacuum, it should be connected to the intake manifold so that the flap can adjust according to the manifold pressure.

nenad

You are correct about which part he means, but it only has an electrical connection. There is a small vacuum hose on the side (about 1" long), but it just connects to the vacuum solenoid at the bottom essentially connecting to 2 ports that are part of the assembly itself. The vacuum source for it is drawn from within the manifold, and since the whole thing sits inside the manifold, it requires no other external vacuum connection. The electrical connection is simply a switch to allow vacuum to the actuator.

The following is taken from AllData's info. Sorry I couldn't get the diagrams too:



The length of the intake manifold is a critical factor for the torque and power output of a combustion engine.

Strong vacuum is created by the pistons on the intake stroke, which, with the intake valves open, moves the air quantity in the intake manifold. The intake air flow or the air/fuel mixture thereby develops considerable kinetic energy (momentum). Back pressure, created when the intake valves close, immediately begins to expand in the opposite direction. The level of pressure is dependent on the air flow velocity and the gas quantity mass present in the intake manifold.

If the mixture column is quickly accelerated or braked, oscillation occurs, the frequency of which is dependent on intake manifold length. If the engine timing and mixture column oscillations match, then a certain charge effect is attained by means of resonance oscillation. Since the mixture column oscillations are also engine speed dependent, the resonance oscillations at a set intake manifold length can only be attained in particular engine speed range.
In order to make the charge effect available over a broader engine rpm range, engines 104.942/992 are equipped with a "resonance intake manifold". This manifold features a "resonance flap" which effectively makes two different intake manifold lengths available.
A pneumatically controlled resonance flap (22) is located on the intake manifold.
The resonance intake manifold switchover valve (Y22/6) is connected to the resonance flap (22) and is controlled by the engine control module as follows:

No load (vehicle parked) at 3900 rpm
Full load (WOT) at:
(104.942) 3450 rpm
(104.992) 3350 rpm

The intake air flows into the resonance intake manifold (19a) through intake ports, which branch off after the throttle valve, into the air collection housing of the oscillation pipe (19b). The collected air volume is split in half by the resonance flap (22). This leads to a distinct increase in low-end torque.

[jnenad16]

benzfan, thank you for the correction. I couldnt remember where the vacuum connector was plugged in so I assumed it was connected to the manifold.

nenad

[kropsch]

Hi benzfan, nenad and Paul:

Thanks for the help in solving my problem and also for the detailed information. Looking more carefully I found a thin white plastic hose with a black rubber connection that was perfectly connected to the vacuum inlet of the resonator valve.
The engine noise seems to be lower than before, but regarding the torque I still need to evaluate it more.