DaveK

I know it's supposed to operate / self test when I turn the ignition on. I've always wondered whether mine worked - and it's only taken me 4.5 years to see.

I ran the engine, then switched off. When I switch the ignition back on, all I hear is a "click" from the engine bay. Is that it?

Red rooster

Dave,
You can see the end of the resonance flap shaft if you look over the top of the fan housing and down to the crossways resonance tube..You should see the circlip rotate about 90 degrees with the click .

The common problem with this system is loss of vacuum due to leaks etc.
A good test is to just try it- ignition on , when the car has been stood for an hour or so.
Running the motor first will build some vacuum and may cover the effect of a leak !
One old problem used to be the headlight diaphragms leaking on cars with headlight beam adjust on a dash control. Those lights use the same vacuum source ! Occaisionaly the black and white one way valve fails but the number one fault is simply vacuum hoses pulled off .

If resonance stops working the result is a smooth power loss over 6000rpm .

Hard to detect in everyday driving !

Hope that helps

Geoff

DaveK

Thanks. I used to have problems with my headlight adjusters leaking - I fixed them but that was probably 3 years ago now. I'll get my g/f to switch the ignition on when I'm looking down there and we'll see if it works.

JasonAndreas

The iSV makes a clicking sound, your resonance valve will go, "plonk". You can operate the valve manually and then you'll know what to listen for when your gf turns on the ignition..

Red rooster

Jason,
This has the makings of a major hit . Click -plonk or plonk - click !

All the best

Geoff