Need help with BOV

[Prof]

so as soon as you connect up the vac the bov opens and it all goes to pot.
 
As I understood it - and certainly how mine is wired, the BOV should not open on idle, only when you let off after boosting, so in other words only when you have vac on the actuator and boost on the inlet of the BOV.
 
On idle, you should have vac on the actuator and vac on the inlet to the BOV as well.

[cab69er]

think my pal once had this problem and he ended up fitting a larger/stronger spring to overcome the idle vac and keep valve shut. still cant understand why it dies tho as doesnt the fd have no afm?

[NeilSR]

I was expecting a scream at the end of that video, lol

[m1tch]

lol hmm well Prof showed me the same sort of topic on the RX7 club and someone posted this:

Another common problem with BOV\'s is that people tend to "T" off the BOV vacuum line.
Try not to do this!
This just causes the BOV not to open properly.

So I might need to find a separate source for the vac, I don\'t really feel like taking my non adjustable Baileys BOV apart lol

[Nik da Greek]

Dunno how different FC upper inlet manifolds are to the FD ones, but on the FD there are two blanked nipples on the face next to the brake servo vaccuum line take off. One is for a boost gauge, and the other is ideal for a dump valve actuating vacc line. Works fine on mine. Is there such a thing on the FC? might be worth trying.

[DRIFTMOTION]

M1tch, I have noticed that you have no rubber hose from the i/c pipe to bov... would recommend installing a hose between the two for a better seal.

Is the bailey a single piston bov? It looks like it is. which will be no good for the FC as the afm is before the bov and at idle you will have vacuum in the system as the throttle plates are nearly closed. Causing the piston in the bov to open letting un-metered air in to the engine and the ecu cannot cater for this air coming in as the afm is before the bov.

Bailey did do a twin piston bov for cars with afm before the bov... (i.e. air filter, afm then bov) Or a single piston bov with preload adjustment will work on the FC setup, like my Blitz bov on mine. This is because the preload adjuster can be wound in to a sufficient pressure stopping the vacuum at idle to open the bov.

Hope this helps.

[m1tch]

Hmm I thought I have the wrong sort for an FC Prof has the double piston Baileys on his and it works fine hmm so it looks like they are ok for FDs but not FCs *sigh*

[grinder]

i have a blitz one on mine and its fine

[Prof]

Is it possible to put washers behind the springs on the baileys to preload them ?  That might stop it opening on idle vacuum, but it will still open when you have boost on the inlet to the bov and vacuum on the actuator.
 
I also found out that the stock bypass valves *are designed* to leak a little on idle, allowing the engine to drag metered air in to the throttles past the compressor turbine, to provide an easier airpath.  Wthout a check valve, the standard bypass valve will not work as a BOV.

[rx7veilside]

if u have an afm or maf sensor on the fc then no this wont work as the fd is map (manifold pressure)..with a afm if the valve is after the afm then as it opens then yes the car will stall because the ecu has worked out the metered air and then the valve opens and stalls the car because the air has not been metered
thats what the problem is
for a afm fed car u need a twin piston bov that is closed on idle strange that an earlier fc id maf sensor fed and later car is map sensor fed

[Brett]

I shared the vacuum/pressure line that feeds the pressure sensor.

[m1tch]

Hmm should I just sell this shiny Bailey BOV to an FD owner and get my another BOV?

[m1tch]

Oh, and Ive found out how to make the stock recirc valve louder lol, when I was taking off the recirc valve there was a washer in the end of the pipe that fit over the IC pipe outlet end, basically restricts the pressurised air. I took this out, and now my recirc is quieter lol so guess whats going back in tomorrow lol