Is the purge valve normally open or normally closed?

[Wrench Turner]

My m20b25 purge valve behaves in the following way:

With No power the valve allows flow from canister side to engine side but not from engine side to canister side

With power applied the valve does not allow flow either direction.

Thus it’s a normally open valve (one way at least...)

Is this correct? Couldn’t find relevant info in the Bentley. Wiring diagram doesn’t tell me when that circuit is powered. Im assuming it’s powered (closed) all the time except purge conditions.

[Elvir]

My m20b25 purge valve behaves in the following way:

With No power the valve allows flow from canister side to engine side but not from engine side to canister side

With power applied the valve does not allow flow either direction.

Thus it’s a normally open valve (one way at least...)

Is this correct? Couldn’t find relevant info in the Bentley. Wiring diagram doesn’t tell me when that circuit is powered. Im assuming it’s powered (closed) all the time except purge conditions.

Purge valve is opened periodically. When open, excess od fuel vapors enter into engine and burned. If valve fail, he is always open and fuel vapors affect on idle, special when hot/summer. If always closed, there is no vent/breath for fuel tank.

Basic solutions is to remove pipe from fuel vapors tank behind rear wheel and fuel vapors will go into the atmosphere.

[Wrench Turner]

Hi there! I know how basic evap systems function. But I just wanted to confirm this one is normally open, but commanded close. Most of the ones I have dealt with are normally closed but commanded open. I don't believe that venting hydrocarbons to the atmosphere is a "solution."

THe more I think about it, the more I think it could very well be a normally open switch. Vapors are only drawn into the manifold under vacuum so if the car is off, no vapors would be drawn in even though the valve is "open." I think that makes sense?

[Elvir]

Hi there! I know how basic evap systems function. But I just wanted to confirm this one is normally open, but commanded close. Most of the ones I have dealt with are normally closed but commanded open. I don't believe that venting hydrocarbons to the atmosphere is a "solution."

THe more I think about it, the more I think it could very well be a normally open switch. Vapors are only drawn into the manifold under vacuum so if the car is off, no vapors would be drawn in even though the valve is "open." I think that makes sense?

Purge valve system is only ecology nature nothing more. Petrol vapors expand, special when the weather is warm. If valve often open, vapors can flooded intake and affect badly on idle.

On first versions of E30, there is no valve purge system and petrol vapors going into atmosfere.

E30 is old car and if you not sure that old valve works fine, best solutions is to put new valve. But he is not so cheap.