Knowledgebase

What can make cars more sensitive to atmosphere venting;
All you ever needed to know about boost controllers
All you ever needed to know about blow-off valves
How to choose a blow-off-valve
Smoke Testing Boost Leaks
Diverter valve leaks & the effects on engine performance and TMS solutions
Turbo lag and the Turbo Management Systems solution
Lightweight Under-Drive Pulley Kit Performance Testing
The Truth About Compressor Surge
GFB Blow-off valve adjustment for cars that are sensitive to atmosphere venting
Engine doesn't run smoothly (atmo blow-off valve fitted)
Blow-off valve doesn't vent or make any noise
A fluttering sound is heard rather than a 'whoosh'
Blow-off valve doesn't flutter, it makes a 'whoosh' sound
Blow-off valve leaks boost
A smoke test indicates that the blow-off valve is leaking
Blow-off valve cracks open under boost
My Audi or VW's check engine light is on
What is a blow-off valve?
How a blow-off valve works
How to fit a blow-off valve
Which type of blow-off valve makes the fluttering or ‘pigeon' noise?
What makes the GFB Stealth FX and Deceptor Pro blow-off valves different to other blow-off valves on the market?
What boost level can I use with a GFB blow-off valve?
I want my BOV to be noisy, but I've been told that I can't vent a blow-off valve to the atmosphere. What's the deal?
have a WRX Hybrid blow-off valve on my 2002 WRX and there seem to be times when it doesn't blow off, and when it does it isn't very loud. Is there a problem with the valve?
Are GFB blow off valves adjustable?
Is there a possibility that dirt could enter the engine through the trumpets?
Do I need to buy extra parts to configure my WRX Hybrid as a plumb back or vent-to-atmopshere only BOV?
Which blow off valve kit do you recommend for an MY98 WRX with a cat back exhaust and pod filter? Everything else is standard.
I'm having new intercooler piping made and I want to know where the best place to install the blow-off valve is?
How does a boost controller work?
Do GFB boost controllers use a ball and spring?
How much extra boost can I run when using a GFB boost controller?
Why does the boost in my car tend to taper off with increased boost at high RPM?
Is there a dyno graph of the Pulley Kit on the WRX?
Do I need different belts for the pulley kit?
When using a GFB Power Up Pulley Kit, is there any problem with the removal of the harmonic balancer?
What is a harmonic balancer?
Isn't there a loss of torque associated with fitting lightweight pulleys, since the flywheel effect is lost?
Are there any problems associated with under driving the alternator and power steering pump when using a Power-up Pulley Kit?
How much lower is a GFB shifter than the factory one?
I've heard bad stories of gearbox damage from using a short shifter - is this true?
How hard are these units to install?
How much is the throw reduced?
Which blow-off valves will the ‘Whistling Trumpet’ work on?
What does the ‘Whistling Trumpet’ sound like?
  • Tech Articles
  • Troubleshooting

    Proudly installed your shiny new blow-off valve without as much as a cheeky sideways-glance at the instructions, but somehow it's not working properly? Had your race-car-mechanic uncle expertly fit it for you but still ain't gettin' that BOV whoosh? Forum gurus offering you pearls of wisdom like: "Errr, what'd you fit a BOV for?", "GFB BOVs are #*@%, get a brand X that'll fix it!" or "Everyone knows you can't vent-to-atmosphere on a [insert your car]"?

    Don't worry; GFB will have you sorted in no time. But before you ask us, take a good look at this troubleshooting guide; in almost all cases we'll only give you one of the answers that you'll find below anyway. Blow-off valves really are incredibly simple devices and there are very few things that can go wrong with them, so this guide should be all that you need.

    Almost 100% of 'faulty' blow-off valves reported to us turn out to be installed or adjusted incorrectly, and can be rectified very easily; we've almost never found a problem with any of the valves that have been returned. The troubleshooting guide below lists the eight most common BOV problem scenarios and how to fix them. Go on; show your uncle how it's done.

  • FAQs