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[Webby the Bear]

As above, just been reading Paul's thread re bad misfire. One comment was the purge valve. Ashamed to say i've no idea what this is. I've googled and it seems to be to do with emissions but anyone got a baby's answer for me 

How do you test if yours is good/bad?

[05omegav6]

Of the breather pipes...

Two outer join and go to big nipple on breather box behind 135 head.
One goes to small nipple on breather box, next to big nipple.
Last one goes to purge valve, sited above and behind breather box next to HBV.

Pipe runs from this to the drivers side front wheel arch, where the carbon cannister lives. Vent pipe from fuel tank runs to the cannister, and under certain conditions, the ecu opens the purge valve allowing the fumes in the cannister to be drawn into the engine via the breather bridge/plenum

Simples, aye

[Webby the Bear]

Of the breather pipes...

Two outer join and go to big nipple on breather box behind 135 head.
One goes to small nipple on breather box, next to big nipple.
Last one goes to purge valve, sited above and behind breather box next to HBV.

Pipe runs from this to the drivers side front wheel arch, where the carbon cannister lives. Vent pipe from fuel tank runs to the cannister, and under certain conditions, the ecu opens the purge valve allowing the fumes in the cannister to be drawn into the engine via the breather bridge/plenum

Simples, aye

You learn something new everyday! Cheers mate 

So it's to filter out petrol fumes which are disposed of by adding to the inlet manifold.

Question then lol ........

Why does it need to get rid of fumes? is it because (guessing here) these extra fumes equate to extra pressure?

[05omegav6]

It's an environmental thing

Fumes used to vent to atmosphere, now they get burnt first

But yes, essentially the vent is there to prevent the tank from pressurising...

[Webby the Bear]

It's an environmental thing

Fumes used to vent to atmosphere, now they get burnt first

But yes, essentially the vent is there to prevent the tank from pressurising...

Got ya mate thanks!

That makes sense as to why it was suggested then.... if the petrol filler cap hisses when you open it the the normal operation of the fuel pump would be creating a vacuum in the tank, thus the hissing?

i read somewhere about blowing in to the pipe on the breather bridge. that right? 

[05omegav6]

Waste of time if the valve is closed

[Webby the Bear]

Found this from an old post...

pull hose off plenum chamber top ( the smallest of the four )

engine off - should be able to blow through it
ignition on - shouldn't
engine running - shouldn't

This should tell me if anythings fubar'd 

[05omegav6]

Plugging it into the coolant temp sensor doesn't help

Worth noting on the 2.5/3.0 both centre pipes on the breather bridge are the same diameter. 2.6/3.2s are different

[Webby the Bear]

Plugging it into the coolant temp sensor doesn't help

Worth noting on the 2.5/3.0 both centre pipes on the breather bridge are the same diameter. 2.6/3.2s are different

But the test should be the same though, right? on the right middle hose 

coolant temp sensor???  lol

[05omegav6]

Plugging it into the coolant temp sensor doesn't help

Worth noting on the 2.5/3.0 both centre pipes on the breather bridge are the same diameter. 2.6/3.2s are different

But the test should be the same though, right? on the right middle hose 

coolant temp sensor???  lol

Visually check the hose is connected to what you expect, just incase they have been fitted arse backwards

As for the other, when I changed my loom, I managed to plug the purge valve plug onto the coolant temp sensor and vice versa. Had two codes, one for each, but no real issues... right upto the point I switched them back,  and found that I had cooked the temp sensor. This defaulted to -30°C as the coolant temp, so wouldn't start when warm as the ecu emptied the fuel rail into the cylinders prior to cranking. This flooded it summat stupid

[Webby the Bear]

Plugging it into the coolant temp sensor doesn't help

Worth noting on the 2.5/3.0 both centre pipes on the breather bridge are the same diameter. 2.6/3.2s are different

But the test should be the same though, right? on the right middle hose 

coolant temp sensor???  lol

Visually check the hose is connected to what you expect, just incase they have been fitted arse backwards

As for the other, when I changed my loom, I managed to plug the purge valve plug onto the coolant temp sensor and vice versa. Had two codes, one for each, but no real issues... right upto the point I switched them back,  and found that I had cooked the temp sensor. This defaulted to -30°C as the coolant temp, so wouldn't start when warm as the ecu emptied the fuel rail into the cylinders prior to cranking. This flooded it summat stupid

Had the plenum off loads recently... i know they;re hooked up right