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One of the last things for me to do with my Vort is the fast idle at operating temp, was too fast at about 1400rpm. Just screwing in the brass screw on the throttle body at the top wound the idle down to about the 700 mark.

Now, on cold start - got no fast idle

Anyone recall just how it works on the spider , Disco?

I know where it is -about half an hour to get at it at

It is two wires.

I recall looking inside a cold one to see a partially blocked disc? and could blow a little bit through it.

Is it simply on or off, or progressive in its operation?

Any clues appreciated, or full Disco-like explain also equally appreciated

Ay, thanks Gannon, quick work and says a lot !

Would it be asking too much if it was 5V or 12? Me thinking 12.

I'd say mine is a little tired or gunked up (like PCV sytem was before I got to it) and burnt out

8th line down... "current is supplied by the fuel pump circuit"

Id say it would be 12v

they have a constant 12v supplied to them when the ignition is on.

wonder what controls the "certain elapsed time the shutter valve closes" ? Maybe the earth from ECU ?

steptoe wrote:wonder what controls the "certain elapsed time the shutter valve closes" ? Maybe the earth from ECU ?

Its just a heater that gradually closes the valve, it has power for as long as the ignition is on.

The "elapsed time" is the time it takes to heat the bi-metal strip

Yeah, when it cools it relaxes the pieces of laminated metal and spins the shutter to the open position. They still work even un-powered with the engine heat, just takes longer to get to idle speed.

I am sort of used to slow idle@cold with my LPG no fast idle set ups. Play when i have time.

No guys , Subaru and the other manufacturers are a bit smarter than to put ignition power across the "half dumbell" device .
Usually these are wired into something like the fuel pump relay , the reason being that you could have the ignition switched on without the engine running and then the valve would close possibly when it shouldn't .
They figure that if the fuel pump is running so is the engine so if the computer controls the fuel pump relay it also controls either power or earth to the air bypass valve .

These idle up cold start bypass valves as I call them are generally bolted down to some part of the engine that sees coolant like a water log or the iron engine block in some cases .
I'd say the reason is to keep its internal bi metalic strip hot enough to hold the rotary valve closed even with the engine electrics powered down .
These valves can get gummed up and I think a bit of carby cleaner should clean up the gunge .

I'd have to look but from memory this valve fits on top of Spidos water log doesn't it ? I suppose like many things spider it'd be a pain to get off and test/clean out .
And of course original cars have those EFI plugs with the fiddly lock wire .

My guess is that if the valve was stuck open and you've screwed the TBs air bypass nearly shut then most of the idle air would be going through the cold start bypass valve . That may explain why you don't get the extra air from the cold start valve - it could be fully or nearly open to start with so can't open any more .
You may want to count the remaining number of 1/2 turns on the TBs bypass screw before its fully closed and don't be surprised if its nearly screwed shut now .
If you have a piece of 1/4" plastic tube about a foot long you can place one end near the cold bypass valve and the other near your ear , you may be able to hear air running through it when it should be closed .

If the valve proves to be RS you may be able to find a second hand one off say a Nissan of the same era , try to get one off a similar capacity engine if possible because it will have the closest air bypass capacity to your EA82 .
Easy to test with an injector plug and wires bridged across a battery .

A .

Gannon reminded us of line eight in post#4 of the fuel pump circuit supply, likely pos +, the ECU might control the neg switching.

You know , when it was out I was able to blow just a little through the air valve - it probably should have been everythng or nothing - in hindsight. I did have a few other things to think about - like why was this pristine beast down to half full sump - did it blow a lot of weed by engine or turbo? Was it just some bloody awful leaking seals and why not at least kept topped up? I'd yet to drive it so knew some things would have to keep for another time. It is running pretty sweet and just needs some PCV monitoring as well .Considering the lvel of gunk in all PCV hoses etc, both the control solenoids were also non functioning little wonder if the valve is also gunked up needing a clean out. NNcool Nev is working on a write up on service and repair

I stand corrected about the power supply, the fuel pump circuit makes sense as Adrain said.