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Vacuum Valve


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Hi guys,  i'm fresh owner of RCF. Meybe this  is not a problem or it is. From 3 weeks I can hear under the hood that there is a strange noise when car is shot down. It seems this is one of two vacuum valve. It sound like "click" many times. What is going on. There are two thin tubes connect to it. One is strange guided because it's going at the back of the Battery and goes strigh down and then somehwere else. Im not sure if  its bended somewhere. It is normal that this valve is working even when car is not runnig?

20231017_192513.jpg

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This vac valve is used to move the flap in the intake box.  Think it comes from the intake manifold around the throttle body and goes via the valve to the intake box.  Don’t think it should be making any noise….

 Does the engine change not around 4500rpm?

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Yes it does. After higher rev engine sound different. I have two valves, everywhere where i found i saw just one, strange. I will record video with sound next time. 

 

BTW, somewhere here in forum i read that it is not recomended to disconect electrical plug from that valves, is this correct?

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3 minutes ago, Grzegorz M said:

Yes it does. After higher rev engine sound different. I have two valves, everywhere where i found i saw just one, strange. I will record video with sound next time. 

 

BTW, somewhere here in forum i read that it is not recomended to disconect electrical plug from that valves, is this correct?

oh yea, never actually noticed that!!  Not a clue what that is!  I can only assume its been added at a later date, do you have a valved exhaust or something??

If you disconnect the plug (for the oem solenoid) I believe you will get an Engine Warning Light.

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8 minutes ago, Jgtcracer said:

oh yea, never actually noticed that!!  Not a clue what that is!  I can only assume its been added at a later date, do you have a valved exhaust or something??

If you disconnect the plug (for the oem solenoid) I believe you will get an Engine Warning Light.

As I know I have custom made exaust with flap controller through pilot. 

 

 

Do You actually blocked this flap pipe with vacuum cap? After this flap will be  fully open all time? Is this safe?

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43 minutes ago, Grzegorz M said:

As I know I have custom made exaust with flap controller through pilot. 

 

 

Do You actually blocked this flap pipe with vacuum cap? After this flap will be  fully open all time? Is this safe?

Which solenoid are you on about?  Blanking the oem one with make your intake flap open up all time and give a deeper growl at lower revs.  Perfectly safe….

 Not a clue what blanking the other one will do, if you follow the pipes you may be able to work out what it does.  Could it be getting used to control the switchable valve in the exhaust?

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The valve on the left of your picture is the standard one. The one attached to the grounding bracket isn't, although it looks a genuine Toyota part with correct connector so maybe it has been relocated.

What is the red cable/hose in the bottom left of your picture, and also there appears to be a vacuum hose blocked off.

This is a good pic of the factory engine bay:

The_engine_room_of_Lexus_RC_F_%E2%80%9CC

 

 

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  • 1 month later...
On 10/26/2023 at 10:36 PM, Jgtcracer said:

This vac valve is used to move the flap in the intake box.  Think it comes from the intake manifold around the throttle body and goes via the valve to the intake box.  Don’t think it should be making any noise….

 Does the engine change not around 4500rpm?

Hi once again. I have a question about this vacuum valve. Is this possible during stop to check if its works or not? What are conditions to activate this valve? 

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16 hours ago, Grzegorz M said:

Hi once again. I have a question about this vacuum valve. Is this possible during stop to check if its works or not? What are conditions to activate this valve? 

1) Remove the vacume pipe, start the car. The pipe should be sucking in air.

2) Drive over 4500 RPM and notice the intake sound.

They're the easiest way to check.

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Have you a aftermarket valved exhaust fitted….. i have  a Armytrix system which is a valved exhaust and have a second vacuumed solenoid for the operating the valves….although my valve system has been fitted  on the bulk head

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