GTS quick exhaust valve open

[Ryandoc]

Folks

I know in my GTS the exhaust valves open as soon as the accelerator is pressed, does this also happen in neutral ?

Assume answer is yes ?

Cheers

 

[Scaf]

I think the way it works is as you start the car the valves are open, they close once there is vacuum created by the engine
running - unless you have the sport button pressed.

I don't think there is any link to accelerator and or neutral

 

[murph7355]

I think the way it works is as you start the car the valves are open, they close once there is vacuum created by the engine
running - unless you have the sport button pressed.

I don't think there is any link to accelerator and or neutral

I think that's right.

 

[Felonious Crud]

I think the way it works is as you start the car the valves are open, they close once there is vacuum created by the engine
running - unless you have the sport button pressed.

I don't think there is any link to accelerator and or neutral

I think that's right.

Yes, me too.

 

[Contigo]

The vacuum pipe/s are connected to the intake/inlet manifold. The valves are kept closed by the vacuum hence when the engine is first started the valves are open based on lack of vacuum.

The SPORT button controls a solenoid which overrides the vacuum control and leaves the valves open.

 

[Ryandoc]

Didnt realise it was vacuum controlled, does that explain the probably 10-20 seconds of loudness and then it quietens down from start-up as thats when the initial vacuum is building up? And that after that short period is pver they are infact then shut even when sat still in neautral?

My reason for asking is just so i can visually check they are operating ok, so assuming I leave the car for a minute, I have vacuum in the system they would then be closed sat still and in neautral, and if I blip the throttle then (again still sat still in neautral) that i could see them operating?

Cheers

 

[Contigo]

Why would they open when you blip?

They are open all the time when the engine is off. They are open when the SPORTS button is pressed (and open more at higher revs)

 

[Ryandoc]

Getting lost here, my understanding was in the S they open as soon as you touch the throttle. I have it wrong way around then, they are open in relaxed state (engine off) and vacuum system does the closing, but like air fail safe Lordy brakes if you like, no air on then brakes are on.

So for an idiots guide whilst sat still how can I check they operate? As in physically see them moving ?

 

[Contigo]

When not in SPORT mode (pressing the SPORT button) the valves are closed and the car should be as quiet as a church mouse. As soon as you press the SPORT button (even in Neutral and idle) you should hear the valves open (you can hear a metal sound) and then a deeper rumble. Revving the car now should raise a smile.

When under load in SPORT I am led to believe that the valves open and close further through the rev range.

This is how it works on my GTS MC Shift.

 

[Scaf]

It's definitely nothing to do wth throttle....... as explained they are open on start up and will close within a 10 secs or so as vacuum build up, then it will quieten down (unless you still have sport activated).

To open and close them when running just alternate between Sport mode and normal mode using the sport button.

You should easily hear the difference

 

[Felonious Crud]

It's definitely nothing to do wth throttle....... as explained they are open on start up and will close within a 10 secs or so as vacuum build up, then it will quieten down (unless you still have sport activated).

To open and close them when running just alternate between Sport mode and normal mode using the sport button.

You should easily hear the difference

That's my understanding. They are either open or closed, no half-way houses.

 

[StuartW]

That's my understanding. They are either open or closed, no half

Agreed

 

[Contigo]

That's my understanding. They are either open or closed, no half-way houses.

They open more further up the rev range. Back pressure related I'm told.

 

[Ryandoc]

So ignoring the 10-20 second start up sequence.

I sit with engine running and in neutral if I press the sport button on off I should see the mechanism below operate? Getting slightly conflicting info if I read it right they either completely open when I press sport full stop or they open a little / lot in neutral and open more as you do actuall press the throttle ?

Just want to check their operation that's all, physically see them moving whilst sat still

 

[StuartW]

Regardless of how much they open, in an MC-S you will see & hear the valves open when pressing the sport button with the engine running in neutral. You will hear the valves open, if you are looking at them you will also see them in operation, and you will hear the exhaust note change.

 

[Ryandoc]

Perfect thsnks, will see how mine are performing

 

[granturismo]

If you can't hear the difference during idle then there is something wrong, its definitely deeper burble

 

[Contigo]

Exactly it's like church mouse quiet then deep burble.

10 seconds is too long. I fired mine up today and they are open for 2-3 seconds MAX!

 

[StuartW]

Honestly Phil, all of these exhaust mods must have wrecked your hearing - even in non sports mode, it's still not a quiet car by any means!

 

[Contigo]

Honestly Phil, all of these exhaust mods must have wrecked your hearing - even in non sports mode, it's still not a quiet car by any means!

Yours has to be fair got more mods than mine and I would say that at idle with valves closed it is no louder than our everyday Petrol SUV.