tial BOV not operating correctly

[jonra23]

What is the brass fitting in the BOV vacuum line that is shown in the BOV pic?

regards
jon

[EVOSTi]

that was to reduce the line from the larger fitting on the manifold to the smaller one on the BOV. its internal diameter is larger than that of the smaller vacuum hoses currently connected to the manifold fitting, that was originally connected to the BOV.

[Aust162]

probably a silly suggestion, but that brass fitting or hosing isn't blocked at all? have you checked it recently?

What i would do is try a process of elimination.
Test the bov is at fault or the vacc connection: have you got another bov that has the same flange that you can temp fit up?
Also pull the bov apart. make sure the piston is moving well, lightly oil it and put it back together. maybe try a different spring too? or check to see if the spring isn't getting jammed somehow..

If you can get another bov to test (or you have one) and you find it works, then it has to be the vacc line/connection issue.. they are pretty simple devices.

[EVOSTi]

the hoses i put on today were brand new and not restricted.

the BOV actually can open and close fine. like i previously mentioned when you open the bonnet and give the throttle a quick stab open, the BOV fully opens and closes. its only under driving conditions when the throttle is snapped shut, you get loud compressor surge then half a second later the BOV opens but nearly nothing comes out.

also i think the chances of another BOV mounting to the tial fitting are slim to none.

[jonra23]

Looks like you have the vacuum supply well and truly covered.

Don't think i can be much more help.

Only thing i can think of is a hole in the BOV diaphragm but as you say it works when you give the throttle a quick stab when it would be making little boost, if you suck on the vacuum hose does BOV open and hold vacuum?

Almost sounds like it may be jamming under pressure?

regards
jon

[BigWorm]

The breather port is definitely your problem, it doesn't actually go into the plenum, instead it follows a passage up to in front of the throttle body.
What you could do with this, although it would once again require manifold removal to clear out the swarf, is to just shove a drill through that port on the plenum, then unbolt the throttle body & block up the now exposed port (as simple as cutting out a new gasket & not cutting a hole for the port).

[Aust162]

Thinking about it.. i wonder if the throttle body plate is actually shutting properly?

the intercooler piping/core need to be pressurized for the bov to release, so it needs to shut at the tb. and seeing how close it's mounted to the tb.

when you say it works by pulling the tb open by hand, your "physically"shutting it. under driving conditions if the tb isnt sealing or the cable has slack in it, then it wont seal it shut the same way as doing it manually by hand.

The compressor surge before the bov noise shows that the bov isnt reacting as fast as it should.
I think maybe accellerator cable, tb linkage.. But you would most likely notice this with how the car drives?

just an idea

[EVOSTi]

nah its not the throttle cable, the cable has some slack when its closed and isnt being held open by anything.

joel, i seem to remember something about the breather port going back to before the throttle body, i think from when i read karl's post on getting the mani cut and shut. but instead of drilling through it i will just remove the yellow sensor tomorrow and take it to the valve shop near my work, hopefully they have a barbed fitting with the same thread as the sensor.
thanks for all the replies, but i need to wait 24hours before i can hook people up with some rep

[jonra23]

Bigworm
Good catch +ve rep.

regards
jon

[EVOSTi]

i got a fitting for the spot where the yellow sensor went today, fitted it all up and on the 5min drive home, it seems to have almost completely eliminated the problem, thanks guys!!!
it still gets a sliiiight amount of surge under some conditions, but as a whole im getting the BOV opperating under boost, i would even say its quiter under most conditions.
so its definately much better. rep all round when i can spread it!

[Aust162]

awesome, good news mate.