Hello all,
I have a strange issue that I can't seem to figure out. When I'm cruising, usually in 5th going up slight hills on the highway, and the car begins to build a little boost, i hear a high pitched 'woooo' sound (lol make the highest pitch 'woo' sound you can with your mouth if you're sitting alone, and you're probably replicating it.) I can either hold the throttle there and sustain the sound, or let off and it'll quit, or throttle into positive boost and it'll quit. Took me forever to figure out the problem is pretty consistently related to 0 vacuum level. At first I thought it may be vibration from solid alu mounts or something- a product of metal on metal resonance, sound frequency related.. but I don't think that's it. I picture someone blowing over the mouth of a glass bottle when I hear the sound, so I think it's air turbulence/ resonance inside the intake manifold/ intake system as a whole.. but I have no idea how I might stop it. It doesn't really seem to negatively affect performance or anything for that matter, it's just slightly annoying and I'd like to identify its cause and keep it from happening.
The sound seems to have started occurring once I installed a bosch bpv from a saab 9-3. I'm running a stock rebuilt 7m with a 57 trim ct26, stock 3000 pipe and stock afm and accordian hose, recirculating the bov. Car also has 2.5" hard pipes and upgraded intercooler, apexi intake and 3" downpipe to 2.5" exhaust. Stock turbo elbow. Basically the whole vacuum system is in place and routed as it is stock. No aftermarket boost controller, or electronic management. The car boosts about 10 lbs as a product of simply bolting everything on. Never adjusted the boost levels for fear of being near fuel cut..
Anybody else ever experienced this? Any ideas out there?
Thanks,
Aaron
I have a strange issue that I can't seem to figure out. When I'm cruising, usually in 5th going up slight hills on the highway, and the car begins to build a little boost, i hear a high pitched 'woooo' sound (lol make the highest pitch 'woo' sound you can with your mouth if you're sitting alone, and you're probably replicating it.) I can either hold the throttle there and sustain the sound, or let off and it'll quit, or throttle into positive boost and it'll quit. Took me forever to figure out the problem is pretty consistently related to 0 vacuum level. At first I thought it may be vibration from solid alu mounts or something- a product of metal on metal resonance, sound frequency related.. but I don't think that's it. I picture someone blowing over the mouth of a glass bottle when I hear the sound, so I think it's air turbulence/ resonance inside the intake manifold/ intake system as a whole.. but I have no idea how I might stop it. It doesn't really seem to negatively affect performance or anything for that matter, it's just slightly annoying and I'd like to identify its cause and keep it from happening.
The sound seems to have started occurring once I installed a bosch bpv from a saab 9-3. I'm running a stock rebuilt 7m with a 57 trim ct26, stock 3000 pipe and stock afm and accordian hose, recirculating the bov. Car also has 2.5" hard pipes and upgraded intercooler, apexi intake and 3" downpipe to 2.5" exhaust. Stock turbo elbow. Basically the whole vacuum system is in place and routed as it is stock. No aftermarket boost controller, or electronic management. The car boosts about 10 lbs as a product of simply bolting everything on. Never adjusted the boost levels for fear of being near fuel cut..
Anybody else ever experienced this? Any ideas out there?
Thanks,
Aaron
