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Discussion Starter · #1 ·
To all you guys that claim the isv does not regulate boost pressure or bleed off pressure when knocking (for ex. cvovp), here is the evidence that it does (taken from sweedish document on all the specifics of the G60 engine). http://hem.passagen.se/corradog60/g60.doc

TRANSLATION:

Boost pressure regulation.
It's purpose is that, in relation to the engine revs and the danger of knocking, limit the boost pressure. The limitation and re-routing of air to the G-charger's inlet side happens through the idle stabilizer valve. The Digifant control unit controls the isv by concidering revs (from Hall sensor), the knocking sensor signal and the pressure from the Map sensor.
[PICTURE]
It works like this.
From the engine revs reach 5600 (max load) to it's disengagement rev of 6200, the boost pressure is reduced by 0.2 to 0.15 bar (2-3 psi). This gives a smoother "entrance" to the rev limiter protection. More important is the need to limit the boost pressure (in addition to reducing the ignition timing advance) to reduce to possibility of knocking. The boost pressure kan in a case like that (with knock) be limited to 0.4 bar (5.8 psi) which prevents that critical exhaust temperatures are formed.
 

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Re: The ISV DOES regulate boost pressure, and bleed off boost! (CorradoFANATIC)

i'll make sure to tell that to the guys at Bosch. lol.
if i make you a drawing with oh lets say Polish writing stating the exact opposite will you believe me then. it'll be a nice drawing just like yours.
show me a schemtaic of the control unit with a breakdown of individual functions where this secondary 'knock control' is evident.
in accordance to your drawing there would be procedure to check this bleed off and its duration as well as at what rpm it happens. there is none. till i see actual proof, not a laymans drawing, i will stand by my reasoning and that of the engineers at Bosch. thanks.
 

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Re: The ISV DOES regulate boost pressure, and bleed off boost! (G60ING)

and here my friend you shoot yourself in the foot. notice the direction of flow (follow the arrows)
.
this ISV is also used on golf and jetta (digi) models. its nothing more than a valve allowing air into the intake mani. during idle. think auto choke on a carb. same prinsipal.
 

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Discussion Starter · #6 ·
Re: The ISV DOES regulate boost pressure, and bleed off boost! (cvovp)

I didn't make the picture, it's a bad scan from a manual from the sweedish v.a.g. dealership.


[Modified by CorradoFANATIC, 12:57 PM 11-29-2001]
 

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