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When your intake system is under boost and you let
off the throttle, closing the throttle plate, a pressure wave
builds and heads back towards the turbo intake turbine. This can
be very damaging to your turbo if it is present for an extended
period of time. To relieve this you have a Blow-Off-Valve, called
Auxiliary Air Valve by Toyota, that opens when the system is under
vacuum, the throttle plate is closed. This vents the air back
into the accordion hose relieving the back pressure.
To test if yours works take your BOV and see if
you can blow through it. If you can it is, like mine was, toast
and is leaking your boost. You can buy the one from Toyota but
those are expensive. There are two other options that I know of
which are to use the BOV from a SAAB or Porsche and are $25-$30.
There is a SOGI
tip on installing them, as well as this one. I find mine easier
because you don't need a lot of custom adapters.
Tools: |
Pliers |
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Utility knife or hose cutters |
Materials: |
Porsche Air Cut Off Valve(993.110.337.50) |
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2 Hose clamps to fit your 1"
ID hose |
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Small section of straight 1"ID hose |
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Flared bypass-hose from Kragen (B70773) |
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Flat head screwdriver |
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21cm of 6.0mm vacuum hose |
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1/8" x 11/64" Vacuum Elbow (VACU-TITE
47410) |
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1 Hose clamp for 6mm vacuum hose |
Teardown
1. |
Disconnect the BOV vacuum line from
the chrome pipe on the engine.
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2. |
With the pliers move the hose clamps on the
two air hoses on the BOV. |
3. |
Remove the BOV hoses from the 3000 pipe and
the accordion pipe they may be frozen on so try twisting
or if all else fails cut them off. |
While you are here
1. |
There is nothing really to look at when doing
this upgrade as it is one of the easier ones where you don't
have to tear lots apart to do. |
Assembly
1. |
Cut
the straight section of 1"ID hose 3cm long so it will
fit perfectly over the bottom section of the BOV so it just
matches flush with the bottom section. Cut the flared heater
hose section at the point that is 16cm from the flared edge
measuring along the outside of the bend. |
2. |
Place
the two hose sections on the Porsche BOV. |
3. |
Place
the two hose clamps on the BOV hose sections loosely tightening
them down. |
4 |
Now the vacuum elbow will just
loosely fit inside the 6mm vacuum tubing. But because of
the short length and how rigid the tubing is we shouldn't
have to worry about it blowing off. But if it blows off
that is BAD so I used a small hose clamp. The picture at
the top shows what it is like put together. |
Reinstall
1. |
Place the longer section of hose on the 3000
pipe. |
2. |
Push the lower section of the BOV over the
according hose connection. It will just make a good seal.
It isn't on the accordion hose super tight but this side
does not require a connection that is very tight. Mine was
also held down by the hose above giving some support. |
3. |
Tighten the hose clamps on the wider hose
with the flat head screwdriver. |
4. |
Use the pliers to place the hose clamp on
the 3000 Pipe connection. |
5. |
Place the 6mm opening of the vacuum hose
on the chrome connection next to the 3000 pipe. Then place
the other end on the BOV. The hose connection at the BOV
side is a bit loose so tuck the hose clamp on the BOV end
in the BOV "moat" so it will keep it from popping
off. |
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