bosch blow off valves

[TTT]

I took the return line off one time to see what it looks like when the car is on.

well the car spat, splutered, ran rich and so on, but for like half a minute that I ran it like that, I can see that it was open and recirculating..

you could see the piston is up and you could feel the air coming out of it..

it's normal.

the BOSCH bov is the came.

[Roy]

Isnt the return line behind the AFM, removing it is opening a closed system to the atmosphere. Or did you block it when you removed it?

Its possible that metred air was escaping before the throttle body/idle control valve. Hence the rough idle and running.

[Cool Hand Luke]

That makes sence about the bov now.. thanks it sounds unreal when it goes Bzshhhhhh choo chooo choo chooo. Getting real complex with the sounds here . The car idles fine when the return line is taken off, but only if its blocked as its leaking air. That would tell me also that the std bov is shut during idle. As soon as you unblock the return line it idles terribly

[TTT]

the whole story is that when I bought my car, it had an atmo SARD R2D2 bov on it.

so the return was already blocked off.

when I changed it to the original bov I thought I would test it venting to atmo to see how it sounded/went..

so that's when I saw that it stays open at idle.

[Dr Boost]

I would have to agree that the stock bov leaks at idle. The first thing i did when i got my car was vent the stock bov to atmo, and blocked the return hose. the car idled terribly. I thought about this for a long time and the only explanation is the one gtst gave.

Back at the beginning of the thread someone said that the bosch bov had to be plumbed back, why? because it also leaks at idle? My friend has a turbo gemini with a bosch bov and it is real loud. It idles fine, is this because it has microtech (MAP sensor instead of AFM)?

Fluttering sound is bad. It may sound cool to some but it sounds like turbo damage to me.

[walkoau]

GTST

you were right, my friends new gts-t had a ruber door stop it the bov plumback line. it was totally blocked. this was causing the flutter. anyway everything is the way it should be now.

im pissed at the person who put the rubber stop in there cause it was a real bitch to get out, cause it had worked its way right down the ''s'' bends of the steel return pipe. it ended up taking 2 hours to get the thing out.

its a really stupid idea to block ur BOV line just to get the fluttering noise(only to cause you trouble later, not to mention money)

[qikr33]

for anyone that wants to try this "fluttering" noise and is thinking to install a door stopper or something like that ....all u gotta do is take off the vacume hose running to the bov and plug the end.Having said this ,as cool as it sounds i wouldnt do this for too long or hit high boost as it will cause the turbo problems.

[TTT]

1.) I was the one that said the BOSCH bov had to be plumbed back, but I was obviously talking in a SKYLINE run AFM.

on a car with a MAP setup, you can have the BOSCH vent to atmo.

but "YES, the BOSCH bovs also stay open at idle.

2.)WALKOAU - I'm glad you found the blockage..

I have to say, I have no idea how the hell you were able to get a door stop out from near the "S" bend in the return line without cutting the thing open or at least punching the wall a few times due to being so annoyed.

3.)QIKR33..

doing what you said "remove vacuum line...etc..."

will not work too well.

you will hear a slight flutter but you will find that your car will not run more than 5psi boost.

this is because when you start boosting in your car (in normal setup) the boost pressure builds up in the pipe below the bov and the vacuum line (while boosting) also has positive pressure pushing the bov piston down, so the bov will stay shut.

when you back off (to change gears), the pressure in the manifold (and so the vacuum line of the bov) turns to vacuum and sucks the piston up and the pressure in the pipes under the bov PUSHES the bov piston up and it "BLOWS OFF"

Now, if you simply take the vacuum line off and block it, when boosting, there is enough pressure in the pipes below to push the piston up and the bov will leak anything over 5psi, because there is no pressure above the bov in the vacuum line..

hope this helps.

I don't recommend it, but for those who want the fluttering noise, then just take the bov off, sit it down on a piece of sheet metal, draw the outline of the base, cut it out, drill the holes for the 2 bolts, then put that under the bov so that it is basically blocked off at the pipes.

then sit the bov on top, bolt it all up and it all looks stock but it will flutter everytime you back off the loud pedal..

like I said, I DON'T RECOMMEND THIS!!!

[Cool Hand Luke]

What about i get a stronger spring for mine, so that it doesnt work in vacuum. Are they rebuildable?

[TTT]

you can't change the spring in the stock bov.

no they are not rebuildable.

and I've had enough on this thread.

too many bov questions and so on.

all the info I give is enough...

just leave the damn thing alone.

if you really want, you can do the stock bov mod that I did and am very happy with...

do a search in this section on "bov mod"

TT