Other than controlling purges ?

if it's the 1 im thinking of it's to do with fuel vapours when the engine is off and running

So it won't effect the overal running of the car then if it or it's connection is faulty ?

Does the air from the 2 connecting pipes just go to the canister behind the headlight then ?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Scott.T:
<B>So it won't effect the overal running of the car then if it or it's connection is faulty ?

Does the air from the 2 connecting pipes just go to the canister behind the headlight then ?[/quote]

Hi Scott,
The Purge valve is used to control the flow of fuel vapours from the purge cannister (sometimes referred to as the charcoal cannister). Fuel vapours from the petrol tank are stored in the purge cannister and then the purge valve controls the flow of them into the intake system. These fumes/vapours are then combusted with the fuel injected from the injectors.
The fuel tank is then "purged" of its vapour.

The idea is that this will reduce the evaporative emissions from your fuel tank. Older cars without a purge system have a small hole in the filler cap to constantly vent the tank.

Generally speaking an engine will run perfectly well without the purge connected. The pipework to the purge cannister has a blow-off valve should the tank pressure get to excessive levels.

However, if you have a MY00 or later the ECU will have On-Board-Diagnostics (OBD) that will detect a faulty (or disconnected) purge valve and will illuminate the check engine light on your dash.

Hope the info helps

Paul

Scoob_2000 thanks for that, sound like you know your stuff. When does the Purge control valve open or close then ?

So how about this one then.....what controls the fuel over-run shut-off when you lift off the accelerator at speed. I know on fords that there was an overrun shutoff valve that worked of an earth contact when the throttle was closed, the minimum fuel to keep the car running was pumped in.

This would only work at above 1,600rpm. So I assume that the Subaru may be the same as I can feel it working above 2,000rpm approx. I was just wondering as mine seems a bit to abrupt at times and it may a clue why I have an on Boost hesitation that both Power Engineering and Barratts Subaru are puzzled by.