Vboost always on?

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New2vmax

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Took airbox cover off to check out the carbs and noticed that when I turn key than engage power I hear and see the servo move for vboost than if I twist throttle I see all valves openings at same time. I than started it and realized they all are opening even at idle if I just crack the throttle. Aren't two only supposed to open until about 6,000? Any feedback is appreciated thank you.
 

02GF74

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If you have not got a copy of the service manual, then you should download it, a search will reveal the link.

But yes, from memory the vboost butterflies start to open at around 6,000 rpm.

When the ignition is turned on, the servo motor goes through its initialisation cycle where the butterflies are opened then fully closed.

They should not open until the rpm stated above. The manual has a diagram showing all of this.

The vboost module lives under the left hand scoop.

Either it is faulty, has been replaced by an aftermarket module or a modification has been made so the butterflies are open all the time.

You need to have a look to see what's been done.

I would kinda rule out the first, as when vboost fail, they stop working.
 

RadiumPHX

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Took airbox cover off to check out the carbs and noticed that when I turn key than engage power I hear and see the servo move for vboost than if I twist throttle I see all valves openings at same time. I than started it and realized they all are opening even at idle if I just crack the throttle. Aren't two only supposed to open until about 6,000? Any feedback is appreciated thank you.
The V-boost butterflies are located under the carbs in the intake manifold tract, are you sure you not looking at the throttle butterflies? these all turn/open when you open the throttle allowing air flow into the carbs.
 

02GF74

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^^^^¡ yep, you got it. To see the vboost butterflies would need to remove the carbs, and then need a mirror or endoscope to see them.

Perfectly normal.
 

desert_max

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What you see when Looking down the throat of the carburetors is not the butterflies. Those are your vacuum slides. The butterflies are at 90° to those. As noted that the boost butterflies are in the manifold below the carburetors.
 

maleko89

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The vboost butterflies are between the down stax. One valve for left side one for right.

 

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