Well... disregard the above
Due to thoughtlessness (and lets be honest, a bit of a lack of an understanding of how this idle-valve actually functions), my little mounting block isn't going to work. The way the valve is oriented on the block means it won't mate to the filter backing plate...
Needs to be a bit of a different shape to mount it successfully. So with a bit of luck, will cut out a different shape on the weekend for take two.
So as a bit of a nerd-out digression though, I thought I'd share just exactly how the damn thing works for anyone that cares. Point being, that on my coffee breaks I go searching on the internet for the answers to life's meaningful questions (i.e. how do we get our ITBs working properly with our A/C on our early model MX5s), and more often than not, I end up on some forum reading through posts of someone else's trials and errors. A few are gold, many are not. Maybe this'll help someone.
So here it is with a little bit of a chicken sketch alongside of the in and the out ports, and the inner workings.
First things first - the mechanics of the thing. Basically its a little plastic sleeve around a shaft. It is pulled by vacuum against the housing (the 'sleeve' is the black bit in my sketch, the housing is the hatched bit) to close it up and form a seal. The motor unit pulls the plunger downward (in this picture) and so moves the plastic sleeve away from the housing to let extra air through to adjust idle when AC comes on or whatever.
This is a pulse-width modulation two wire valve. It is a Ford part.
It will be controlled by an MS2. In my reading, the Ford/Bosch valves work (best) at around the 300-320Hz setting in TunerStudio. No idea what that means to be honest but we'll go with that for now. I read somewhere at one point that Ford's method of testing these parts was to bench-run them at a certain frequency for a while and see if they get hot. If they don't get too hot to the touch, then goodoh... That's science for ya.
It has to be wired in the correct polarity. I had it wired the wrong way round first up and nothing happened, switched the wires and it started buzzing away...
This valve uses a 'closed-loop' algorithm. So what this (apparently) means is the ECU will cycle it up (or down) until it determines that a specific RPM has been reached. So I suppose when I hit the AC button it will cycle up and then hunt about a bit until the ECU finds the right RPM.
Thats the theory anyway.
Meanwhile, car is running well enough to do the school runs. Baby steps...
) But again, no amount of fiddling with settings yields a change in the behaviour of the actual valve.
