Vacuum quick release valve

[Guest wheelsport]

How does the vacuum quick release valve work that is outside the air cleaner? In conjunction how does the vacuum operated gismo in the air cleaner work? Could improper operation of this gismo cause an over boost causing a 45 code?

Edited February 6, 2015 by wheelsport (see edit history)

[Hemi Dude]

How does the vacuum quick release valve work that is outside the air cleaner? In conjunction how does the vacuum operated gismo in the air cleaner work? Could improper operation of this gismo cause an over boost causing a 45 code?

I've got to assume here, presume a little and codger some too and you know what all that implies, don't you?

The 'gismo' connector to the small vacuum line and entering the air box is basically a bleed off for the vacuum in that line, when it is no longer needed.

The 'gismo' inside the air box which is connected to the incoming vacuum line and also, down below the air box, to the BIG turbo BOOST outlet hose.

As you accelerate and turbo boost is sent through the BIG outlet hose, the intercooler and then to the throttle body, this produces a large volume of air under pressure.

So, if you snap the throttle pedal closed while under high turbo boost, this volume of air is blocked by the throttle blade in the throttle body which is now closed and that large volume of air has no place to go, EXCEPT, now there is about 25" of intake manifold vacuum.

This vacuum is applied through that 'gismo' on the outside of the air box and this vacuum OPENS the 'gismo' valve in the air box, allowing all this volume of pressure to pass through the valve, from the Big boost hose, and dump into the air box and the intake air stream.

I hope you can follow all this because I had to re-write it a few times just to get it straight.

After all this, I have to tell you NO, overboost is generally caused by a broken line to the waste-gate relay or from the relay to the waste-gate diaphragm. These lines, which looks like a vacuum lines, runs from the intake manifold to the waste-gate relay located on the right side of the engine compartment (passenger side), behind the valve cover and from the relay over to the waste-gate diaphragm mounted on the Turbo.

Boost pressure is used to open the waste-gate and if the line is broken, the waste-gate will not open. Thereby creating overboost.