Unplugging Bov Plumb Back

[Samuel Leonard]

i am addicted to trying to get loud pops and cracks from my RB20. the very light tapping of the accelarator whilst decelerating is a lot of fun. it's fun to try to scare people walking along the foot path with a massive (flame, or possibly just a black cloud and loud bang) am i alone here?

anyway, from what i can see, my blow off valve has a thin hose running back into the intake. when ever you decelerate the ecu dumps fuel in to compensate for the extra oxygen from the blow off valve. if i unplug this will it cause any other problems than loud pops at the time you let off the accelerator?

any opinions would be sweet!

[jrm]

I'm guessing the hose you're talking about is the vacuum tubing at the top of the BoV that acts as a pressure source with the internal spring that ensures that it is closed under normal conditions, and then opening when under pressure differential. This is how BoVs work.

If that's what you're talking about - then removing that will basically screw the operation of the BoV (and car) completely - it'll just be held closed by the pressure of the internal spring, and would leak under any boost conditions. What are you actually trying to achieve? The ECU shouldn't be dumping fuel into the system from the BoV unless you have it plumbed back before the AFM (kinda stupid) or you're using an atmosphere venting BoV.

Anyone else have any comments?

[Samuel Leonard]

I'm guessing the hose you're talking about is the vacuum tubing at the top of the BoV that acts as a pressure source with the internal spring that ensures that it is closed under normal conditions, and then opening when under pressure differential. This is how BoVs work.

If that's what you're talking about - then removing that will basically screw the operation of the BoV (and car) completely - it'll just be held closed by the pressure of the internal spring, and would leak under any boost conditions. What are you actually trying to achieve? The ECU shouldn't be dumping fuel into the system from the BoV unless you have it plumbed back before the AFM (kinda stupid) or you're using an atmosphere venting BoV.

Anyone else have any comments?

that sounds logical. i just didn't understand! how do i delete a thread once it's no longer needed?

[.:: GimpS-R34 ::.]

Yeah, i also like my car to look like i'm a bogan that has a POS car.. I think i look so cool.. goes extra well with my mullet..

PS. you can't delete threads, Its left for the rest of the SAU community to laugh at you..

[mad082]

you can block off the bov so it doesn't let any air out, but while you may get some extra popping, you will also find that the car may stall a lot everytime you push the clutch in to stop at an intersection.

if you want pop flames, etc on deceleration, put a few cracks in the exhaust manifold worked well on my mates falcon after his extractors started to crack at the welds. would backfire and shoot ouf flames. just expect to lose some power

[Samuel Leonard]

you can block off the bov so it doesn't let any air out, but while you may get some extra popping, you will also find that the car may stall a lot everytime you push the clutch in to stop at an intersection.

if you want pop flames, etc on deceleration, put a few cracks in the exhaust manifold worked well on my mates falcon after his extractors started to crack at the welds. would backfire and shoot ouf flames. just expect to lose some power

nah happy to leave it like it is lol wouldn't want to compromise anything for a silly pop!

and to the other guy, you seem like a massive dick. We all make mistakes. I know I'm still learning. I'm 17.

[.:: GimpS-R34 ::.]

LOL i have a name.. Just chill it's the internet dude.. no one really cares what people say on here.. I was just having a laugh.. at your expense yes.. but unless some meaningless words offend you.. don't worry about it..

[lachlanw]

lol at complete wrong ness of OP

"ecu puts in fuel for the air that comes in the blow off valve"

[R31Nismoid]

^ lol...

Apart from that - you do realise making your car purposefully backfire is actually doing damage to everything yes?

[Samuel Leonard]

lol at complete wrong ness of OP

"ecu puts in fuel for the air that comes in the blow off valve"

i may have worded it bad but yes, that is correct. as a result of a plumb back system, the air that get's recirculated through the turbo, some of that gets back into the intake. the ecu expects this so if you block your blow off valve you get loud pops when you decelerate. the ecu still compensates for the non existent excess oxygen and to stop this you would get a tune. i rushed my wording before but i still stand by this statement.

[mad082]

i may have worded it bad but yes, that is correct. as a result of a plumb back system, the air that get's recirculated through the turbo, some of that gets back into the intake. the ecu expects this so if you block your blow off valve you get loud pops when you decelerate. the ecu still compensates for the non existent excess oxygen and to stop this you would get a tune. i rushed my wording before but i still stand by this statement.

actually that is wrong. what happens is that if you block off the bov, when you lift off the accelerator the butterfly in the throttle closes. this leaves a heap of pressurised air with nowhere to go, so it goes out the only opening in the system. this is back through the turbo. this is why you get the "tu-tu-tu" sound. this results in 2 things, 1: your turbo slowing down, and 2: all that air then continues out through the AFM. now since the AFM doesn't know which direction the air is traveling, it thinks that the air is going into the engine, not out of it, so it starts putting in extra fuel. this results in the car stalling, or almost stalling.

in the case of an atmo bov, something slightly different happens. when you lift off the bov opens and vents the pressurised air. this air escaping then sort of sucks more air through the afm. the ecu doesn't realise that this air is just going to vent out of the bov rather than actually go into the engine, so it adds in extra fuel, thus making the car want to stall.

[lachlanw]

^ thanks for writing that . saved me the effort

OP was correct in what happens . just not why it happens