adjusting Greddy type S BOV

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granite statah

New member
I bought the car with BOV installed by PO, so no documentation.

I am holding the adjustment nut + threaded piece in my hand right now. Not good. Is the nut supposed to spin on this threaded "shaft" in order to change the spring stiffness, or is the nut fixed in place? Thanks.

Kirk
 
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TexasAlltrac

New member
The adjustment bolt should not freely spin as everytime it moves a half-turn, your boost will change dramatically (which can be very very bad).

Hopefully you have an aftermarket boostguage to dial the pressure in with.

So, get your boost set to where you want it and while holding the bolt in that exact position, tighten the nut (which goes on the bolt) against the controller housing to keep the bolt from loosening/tightening. Getting some thread-lock would be worthwhile also just to be sure the sucker does not budge. An ounce of prevention is worth a motor-rebuild's worth of cure.
 
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granite statah

New member
Well I just went out and threaded the bolt in......until about halfway, when it sort of popped back out. It looks like the female threads in the BOV are f'ing stripped. Maybe the PO cross-threaded it? Who knows. I threaded it back in some more, then locked the nut down. Hopefully this will be enough to get me home from work.

Might this explain why, when letting off the gas, I get a whistling sound like Andy on Mayberry RFD?

Kirk
 
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TexasAlltrac

New member
To get home, just get it on there where it seals. You will probably be at stock boost if it is just barely on there which is fine.

If it stripped (ouch), maybe you can tap out a new thread and use a one-size-larger bolt and retaining nut? That should hold you indefinantly if it works
 
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granite statah

New member
yeah, that's where I have it. Hopefully it'll seal for the ride home.

Before I try tapping, I'll probably give it a shot of Loctite and see if that seals it up. Otherwise I think you're right. Thanks TXAlltrac.

Kirk
 
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Conrad_Turbo

New member
TexasAlltrac":b6uhzhsb said:
The adjustment bolt should not freely spin as everytime it moves a half-turn, your boost will change dramatically (which can be very very bad).

Hopefully you have an aftermarket boostguage to dial the pressure in with.

So, get your boost set to where you want it and while holding the bolt in that exact position, tighten the nut (which goes on the bolt) against the controller housing to keep the bolt from loosening/tightening. Getting some thread-lock would be worthwhile also just to be sure the sucker does not budge. An ounce of prevention is worth a motor-rebuild's worth of cure.
Click to expand...

The adjustment on a Greddy Type-S BOV doesn't control the turbo boost output. It's not a release valve (like a radiator cap), it opens when there is lower pressure in the intake manifold as compared to the pressure in the intake piping (happens when lifting off the throttle).

There is no real science to adjusting a BOV. It's hard to explain on the internet...but roughly what I do is ensure that I get a pssssht of a second or two at the most, any longer and it's not tight enough. If you get a chattering/chirping sound, then it's too tight.

Even with a MBC (different than a BOV) you cannot adjust the boost level by looking at a boost gauge and adjusting a screw... It's all trial and error, unless you can fit someone under your hood under a high speed run and tell him/her when to tighten the adjustment nut. :p
 
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silverarrow

New member
I had the threads in the bov all stripped in my Type S as well, I just used Loctite on it and a forcefull push while screwing in the adjustment screw as much as I can. It works so far.
 
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RedCelicaTRD

Moderator
You need to have it pretty loose actually. Ive had a type s on my car (i now have a type r) and you would be supprised how much the afm covers up compressor surge. Without the afm i could hear tons of surge while with the afm i couldnt hear any.
 
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granite statah

New member
The drive home Friday was one of the best in a while, carwise.

For the last couple of weeks I've had this oscillating idle at stoplights, between 900-1100 RPM. Like a damn yo-yo. On Friday, rock solid. I had thought there was a vacuum leak somewhere, looks like I found it.

Yesterday I put some Loctite on the bolt. I still think it should be adjusted a little "harder" than it is right now.
Posted: Sat Nov 20, 2004 12:36 am Post subject:

I had the threads in the bov all stripped in my Type S as well, I just used Loctite on it and a forcefull push while screwing in the adjustment screw as much as I can. It works so far.
Click to expand...

Seems like the threads in that aluminum housing are a little on the soft side.....
 
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SLOtrac

New member
A steel bolt om aluminum threads is always sketchy. Instead of retapping the threads and going to a larger bolt, you may want to look into a thread repair kit like Heli coil.
 
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903SGTE

New member
what was your fix for the erratic idle? was it the screw?i have an hks bov and have the same problem at idle.
 
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granite statah

New member
903SGTE":1fk5bopt said:
what was your fix for the erratic idle? was it the screw?i have an hks bov and have the same problem at idle.
Click to expand...

yeah I believe it was the screw. It was hanging in by only a couple of threads and was really loose. I haven't touched anything else. I'm still getting a "whistle" when I let off the gas, but that seems better too. :shrug:
 
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903SGTE

New member
i have moved the adjusting screw on my hks and the idle hasent been affected,ive checked for vacum leaks and havent found any?
 
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