Alright here's the deal,
I have a
cone filter
HKS downpipe and catback
e-manage and E-01
all tuned from at turbo trix
my GFB is 100% recirculating now. When the spring was set at 5 turns, I would let off the throttle at low boost and get the fluttering sound, which I assume is compressor surge. I turned the spring all the way to softest and it is still happening. Also when I'm in 5th at maybe 1/2 throttle, when the turbo starts to spool the car will start to surge very loudly and then stumble. On top of this I get the stumbling and stalling that is apparent on most aftermarket BOV's. If anybody can offer any insight I would greatly appreciate it. If not let me know who wants to buy a use GFB BOV.
Thanks

 

The stumling and stalling sounds like my GFB BOV. Simply reverting to full recirc will not solve this problem. i have tried about a million different combinations of %recirc and spring tension but still have the stalling (near stall) problems. Problem is much worse when the car is under load. I do the best with loose spring tension (1-3 turns) Seems like your car either likes this BOV or not. Good luck.

 

well what i did. actually bluevo(terrence) did was you turn it all the way to the left where you can't turn any more then from there turn 3 1/2 turn and you should be fine =) my setting is 60/40 right now and idle is fine.

 

Man, you guys have it loose. I have mine set around 7 full turns and holds boost like a champ.

 

i heard people having these issues with the GFB. i think i want to try a APS.
anyone know anything about these?

 

the number of turns doesn't affect the amt of boost held

 

so boost being held by the bov doesn't get affected by the spring being loose or tight???

is this true???

 

why don't you go to their web site, or even ask them?
http://www.gofastbits.com.au/index.php

 

Thank you for purchasing the GFB WRX Stealth FX blow off valve, the highest quality and most versatile blow-off valve on the market. We HIGHLY recommend that you familiarize yourself with the operation and adjustments of the Stealth FX BEFORE installing it.

The top of the Stealth FX is divided into three separate sections:

Spring adjusting cap: The spring pre-load is adjusted by turning this cap, clockwise for firmer, and anti-clockwise for softer.

Vacuum nipple ring: Directly under the cap, this ring is free to rotate independently through 360? to make attaching the vacuum hose easier. NOTE: it can be difficult to rotate initially, as it is sealed tightly with o-rings.

Noise adjusting ring: The lower part of the cap is used to adjust the sound level, and is accompanied by a ratchet action to prevent the setting from moving. Rotating this ring clockwise makes the valve louder, anti-clockwise for quieter.


Locate and inspect the factory blow-off (diverter) valve on your car, taking note of the hoses or flanges that connect to it and its orientation. Before removing the factory valve, you should be able to determine if you require additional adaptors simply by visual comparison (for example, if your car has a flange-mounted factory valve, clearly the Stealth FX will not fit on without a suitable adaptor). The standard base of the GFB Universal Stealth FX blow-off valve is for pipe mounting onto 38mm/1.5” pipe, and the standard plumb back outlet is 30mm. A list of available adaptors is found at the end of these instructions, but if in doubt, check out the adaptors page on our website www.gofastbits.com.au, or consult your local dealer.

For cars without factory fitted blow-off valves (generally cars manufactured before about 1990), a location for the Stealth FX must be found on the piping between the turbo outlet and the throttle body, and a suitable adaptor must be welded in that location. GFB has a range of weld-on adaptors in aluminium or stainless steel for this purpose. A hose to connect the Stealth FX plumb back (recirculation) outlet must also be fitted to the piping before the turbo (after the airflow meter if one is installed).

NOTE: GFB recommends mounting the BOV closer to the throttle body rather than the turbo, since some factory turbo piping can cause pressure drops which may affect the performance of the valve. If an intercooler is used, it is preferable to mount the valve after the intercooler, before the throttle.


1) Once a suitable 38mm/1.5mm O.D. metal pipe has been welded to the turbo piping, insert the supplied 38mm o-ring into the internal groove in the base of your Stealth FX, and partially thread the three M5 grub screws into the tapped holes. Smear a little oil or grease on the o-ring, and slide the valve onto the pipe. Make sure that the pipe passes fully through the o-ring and bottoms out in the valve base, and then lock the valve in place firmly with the three grub screws. Thread the supplied nuts onto the ends of the grub screws and tighten – this is to prevent the grub screws working loose.

If you should need to mount your Stealth FX onto a 1” pipe (if for example you are using a GFB MY99-00 WRX or R32 Skyline flange adaptor), you will need to use adaptor part # 5335 for this purpose (see adjacent pic). The 5335 adaptor is a smaller version of the standard Stealth FX base, and comes with the necessary o-ring and grub screws. Simply remove the small 3mm grub screw from the side of the Stealth FX, and unscrew the standard base. Replace it with the new base adaptor and re-install the grub screw.

2) Most factory valves are fitted with a hose that returns the vented air to the intake prior to the turbo inlet (plumb back system). If your car does not have a return hose, one should be installed that vents the air into the inlet before the turbo. If your car has an air flow meter, the hose should be installed so that the air enters the system between the air flow meter and the turbo inlet. This hose should then be connected to the plumb back outlet of your GFB blow-off valve (opposite the trumpet) and secured with a hose clamp.

3) Connect the gold vacuum nipple on the top of the GFB valve to a suitable manifold vacuum source (after the throttle body), using rubber or silicone vacuum hose of at least 4mm I.D. Try to avoid attaching any other hoses to the vacuum hose and keep it as short as possible, as this will ensure rapid response from your GFB valve.


WARNING: DO NOT ATTEMPT TO DIS-ASSEMBLE YOUR STEALTH FX, DOING SO WILL VOID YOUR WARRANTY AND COULD POSSIBLY DAMAGE IT BEYOND REPAIR..


Adjusting the Hybrid valve


The spring pre-load DOES NOT need to be adjusted to hold different boost levels. The valve will stay shut regardless of boost pressure or spring pressure as long as the vacuum hose is properly connected. Rather, the spring adjustment changes how easily the valve opens when you lift the throttle, and how long it stays open when it vents. It is also used to accommodate variations in manifold vacuum levels on different cars. There are 11 full turns of spring adjustment, and stops at both ends of travel.
With the car idling at normal operating temperature, start with the spring adjustment at the softest setting (anti-clockwise). Watch the piston through the trumpet (not too closely!), stab the throttle and quickly lift off. The piston should lift and vent, then close slowly and smoothly. If the piston remains slightly open as the engine returns to idle, tighten the spring a few turns until it closes fully at idle. This is a good “rough” setting to begin with. For cars with airflow meters, the spring can sometimes take a little more fine tuning according to the following guide.


If you notice any of the following symptoms, turn the nipple clockwise until the problem disappears.
• The piston is open at idle
• The valve continues to vent too long, causing the engine to “stumble” as it returns to idle speed
• If when driving you notice hesitations between gears or loud/excessive backfiring from the exhaust


If when driving a significant fluttering noise is heard (at full throttle), turn the nipple anti-clockwise a few turns.
NOTE: There is a range of around 4-5 turns within which your valve will operate properly, and if it is outside this range it will be immediately noticeable in the symptoms described above. Also note that you cannot damage your engine by experimenting with the adjustment. If you notice none of the symptoms mentioned above, then simply leave it where it is.



Adjusting the noise


You will be able to see that turning the noise adjusting ring clockwise will open up the trumpet outlet more, making the valve louder, whilst anti-clockwise will open up more of the plumb back outlet for quiet operation. Turning the valve fully anti-clockwise until it stops will close off the trumpet completely, and the valve will operate like a factory diverter. Conversely, turning it fully clockwise will make it vent completely to atmosphere, which is the loudest setting. There is an indicator on the side of the body which shows the relative position of the noise setting.
Do not be afraid to experiment with the spring and noise settings. As you rotate the noise-adjusting ring you will need to move the vacuum nipple as well to prevent the vacuum hose from kinking (the vacuum nipple ring is sealed by o-rings, and can be relatively tight to move - this is quite normal). You do not need to re-adjust the spring when changes to noise are made.


Maintenance


All GFB valves are designed to be as maintenance free as possible. In most cars the small amount of crankcase and rocker-cover blow-by oil that is directed into the intake system is enough to keep the piston well lubricated. In cars that utilize an aftermarket oil catch-can (or if you notice the movement of the valve is not smooth), it does pay to periodically lubricate the piston every 2 months or so with engine oil. This can be done by applying a small amount to the piston surface through the trumpet and the underside of the valve, and working the piston up and down by hand. It is a good idea to keep the trumpet area clean and free from oil, as dirt can be attracted by excess oil and can cause damage to the piston.
NOTE: The Stealth FX is assembled using a light grease on the piston, which during the first week or two of use can slow the operation of the valve slightly until it “beds in”. You may notice the venting characteristics of the valve changing slightly in the initial period, this is completely normal.


Troubleshooting


Problem: The valve does not blow off no matter how hard the engine is revved.
Solution:
Check the spring pre-load setting, try loosening it by turning the chrome cap anti-clockwise a few turns. If the pre-load is too hard, the valve will have difficulty opening.
Check the vacuum connection. The valve relies on the manifold vacuum signal to help it open. If the signal is weak because of a hose kink or leak, it will not open properly.

Multiple throttle bodies, wild cams or porting can reduce the amount of vacuum available to help open the valve (the Pulsar GTi-R is an example of this). Check the idle vacuum with a gauge, if it falls below 16 inches mercury (in. Hg), you will need a softer spring. Contact your local GFB dealer should you need one.

Ensure the valve is oriented correctly. Most European cars use factory valves with the same size hose fittings on the inlet and the outlet of the valve, and they are usually oriented in the reverse direction to conventional valves. When replacing one of these valve types with a Stealth FX, ensure that the boost pressure enters the bottom and dumps through the sides.


Problem: The valve cracks open under boost.
Check the vacuum connection. The valve relies on the manifold connection to provide boost pressure to keep the piston shut under boost. If there is a leak or kink in the hose, the pressure will be uneven on the top and bottom of the piston, causing it to open.
Mounting the blow-off valve before an intercooler can also cause this, as it is possible to have a large enough pressure drop across the intercooler to cause the valve to crack open.

 

Mine works great, I love it. No problems.