WANTED Blow Off, factory or aftermarket.

[Yasthil]

Tried the dodgy with the factory one, think it's had it. Ideally I'd like ideas on B.O.V's that are inexpensive and not a hassle to fit or run?????

Ran the factory with the plumb back piping plugged(I know, bad, bad owner), worked for all of 45 minutes, cos the engine switches off when coming to stand still after moderate acceleration, and if revved to 4000rpm at idle it'll drop down and switch off.

Any Ideas.......Am not running it like this anymore, but I'm concerned that if I fit an aftermarket one it's gonna do the same thing?????

[mpau009]

Do you mean that you plugged the hole that recirculates? or just unplugged the BOV? because i had that pipe snap, and it was the air getting in the recirc pipe, and not going past the MAF which caused all my problems, wouldn't hold an idle, and would stall all the time.

As far as i am aware there are several members running vent to air BOV's without any hassles.

[You See]

I'm currently running a HKS SSQV ...it's loud and has that distinctive pstttt.
I've got my factory BOV lying around, you're free to have it...let me know your details and if it's not too inconvenient I can drop it off to you. :2thumbsup

[Yasthil]

Thanks for the offer You See, think I'm going to get something after-market. Talked to a guy yesterday who said that it's possible with the recirc pipe blocked that the factory dump valve is leaking under vacuum. Like you say, it's time to mod rather than fix.

[You See]

No problem!
...I've tried Trust Type R, which caused stalling issues....not too sure what the S or RS models are like....but as mentioned above, I've settled with the HKS SSQV. Blitz is also a good one to have...in certain cars it produces a fluttering sound...not sure what it's like in ours tho (has anyone got this in there cars and what is the sound like?)

[detonate]

I had a turbosmart type-ii BOV in my cyborg, and it was easy to make flutter by letting off boost, but keeping it around 0psi.
No idea how good(bad) this is, but then I also blocked the return pipe and let the standard BOV vent to atmo, on my 4G63 VR4 too :P

ahhhhwell.

[Kenneth]

I have a big noisy VTA dump valve. No stalling problems, you just have to make sure you do the correct adjustments.

[VR4 MAD]

I have a big noisy VTA dump valve. No stalling problems, you just have to make sure you do the correct adjustments.

Which are?..................../help :thinking: :speechles

:2thumbsup

[Kenneth]

I adjusted the BOV so that it isn't open at idle. this is fairly easy, and you dont really need a lot of pressure to do this.

Problem is that when you are decelerating your vacuum is higher and can cause your BOV to open anyway and then you stall when you finally come to a stop.

In my car, I also backed out the idle speed adjuster screw a little, reset the ECU and has been fine ever since.

[detonate]

I'm confused as to how vacuum opens the blow off valve?
They open under pressure, when the throttle body closes..... and at idle there should be vacuum.

Am I missing something here?

:book: /pan

[Kenneth]

I'm confused as to how vacuum opens the blow off valve?
They open under pressure, when the throttle body closes..... and at idle there should be vacuum.

Am I missing something here?

:book: /pan

Ideally a BOV opens when there is a pressure DIFFERENCE.

You generally have 2 pressure sources, one is the manifold (after the throttle body) the other the intake pipework before the throttle body.

When you take your foot off the throttle, the pressure in the manifold drops due to restriction caused by the throttle plate. The pressure in the pipe is most likely to increase.

So, in this case you have vacuum pulling at the BOV piston and pressure pushing the piston.

When you are at WOT, you have pressure pushing the piston closed and equal pressure trying to push it open. the difference then is the spring pressure, which should keep the valve closed (unless its buggered or crap) and hold pressure.

When at idle, you have more vacuum in the manifold than in the pipework, so it wants to pull the BOV piston open. (note: some BOVs dont use a piston, but the theory is the same...) When you adjust a BOV for your car, you want to set the spring pressure enough to keep the piston closed under this situation.
When you are decelerating, the vacuum increases considerably as you are running an idle throttle position, but have non-idle RPM. This is often enough to open the BOV.

This is for MAF operated cars though, if you are running MAP + TPS etc, then you can put a air fliter on the BOV and just let it be open at idle as it doesnt matter (so long as it is closed under boost)

[VR4 MAD]

In my car, I also backed out the idle speed adjuster screw a little, reset the ECU and has been fine ever since.

Cheers for that.

When you say "backed out the idle speed adjuster screw", does that increase the idle speed or decrease it. /help

Increase would be my guess but if that's the case doesn't that increase your fuel consumption, especially if you are doing lots of slow around town driving and having to stop at traffic lights all the time (like you must be doing in Auckland traffic)/pan /pan /Grrr :zzz:

BTW what type of BOV are you actually running out of interest.

I have both an HKS SSQV and a Blitz (complete with mount and steel replacement pipework with flange and BOV mount) but haven't decided which to install yet/pan /pan /help

Cheers for your help.

VR4 MAD

[Kenneth]

Cheers for that.

When you say "backed out the idle speed adjuster screw", does that increase the idle speed or decrease it. /help

Increase would be my guess but if that's the case doesn't that increase your fuel consumption, especially if you are doing lots of slow around town driving and having to stop at traffic lights all the time (like you must be doing in Auckland traffic)/pan /pan /Grrr :zzz:


Ahh, this is where things get interesting! ;)
The ECU uses the stepper motor to control your idle speed at idle etc. I believe that it might NOT on deceleration though. (hence stalling problems)
So basically adjusting the idle speed screw usually ends up doing nothing noticable. (however you might want to adjust it carefully 1/2 turn at a time or something just in case)




BTW what type of BOV are you actually running out of interest.

I have both an HKS SSQV and a Blitz (complete with mount and steel replacement pipework with flange and BOV mount) but haven't decided which to install yet/pan /pan /help

Cheers for your help.

VR4 MAD

I use a DragR twin trumpet BOV (off trademe) looked cool to me and sounds good too (personal taste of course) though very loud.

[Yasthil]

Shucks, great to know we've got some technically knowledgable folks around. Makes for a great read.

[Kenneth]

Shucks, great to know we've got some technically knowledgable folks around. Makes for a great read.

at 1:30am? /pan

[VR4 MAD]

at 1:30am? /pan

Look who's watching and replying at 1.59am...................../pan :speechles :zzz: