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Exhaust valves on cold start up
Posted: Fri Jun 01, 2012 9:08 am
by RS4_46
From a cold start is it normal that the exhaust valves are open even though sport mode isnt engaged ? How long do they stay open for?
Re: Exhaust valves on cold start up
Posted: Fri Jun 01, 2012 9:12 am
by adsgreen
Vavles will open as soon as vacuum is removed when the engine is off.
When you start the valves will close with sport mode off and the time taken is dependant on the amount of stored vaccuum in the system.
For my car a completely cold start can take about 1-2 seconds at idle for the valves to shut.
Usually it happens just after the engine settles at idle speed after the initial burst to start.
Re: Exhaust valves on cold start up
Posted: Fri Jun 01, 2012 9:18 am
by RS4_46
adsgreen wrote:Vavles will open as soon as vacuum is removed when the engine is off.
When you start the valves will close with sport mode off and the time taken is dependant on the amount of stored vaccuum in the system.
For my car a completely cold start can take about 1-2 seconds at idle for the valves to shut.
Usually it happens just after the engine settles at idle speed after the initial burst to start.
oh rite thanks. I had a milltek (with valves) fitted yesterday - fired it up this morning just to move it off the drive which took 20-30 secs and valves remained open throughout.
Re: Exhaust valves on cold start up
Posted: Fri Jun 01, 2012 10:22 am
by RSKiwi
adsgreen wrote:Vavles will open as soon as vacuum is removed when the engine is off.
When you start the valves will close with sport mode off and the time taken is dependant on the amount of stored vaccuum in the system.
For my car a completely cold start can take about 1-2 seconds at idle for the valves to shut.
Usually it happens just after the engine settles at idle speed after the initial burst to start.
I thought when you start the RS from cold the valves remain open for around 30 seconds as a sort of 'look at me' feature??? No??
With say MRC's quiet start these stay closed (once vacuum is up) and the revs drop very quickly.
Re: Exhaust valves on cold start up
Posted: Fri Jun 01, 2012 12:19 pm
by adsgreen
RSKiwi wrote:adsgreen wrote:Vavles will open as soon as vacuum is removed when the engine is off.
When you start the valves will close with sport mode off and the time taken is dependant on the amount of stored vaccuum in the system.
For my car a completely cold start can take about 1-2 seconds at idle for the valves to shut.
Usually it happens just after the engine settles at idle speed after the initial burst to start.
I thought when you start the RS from cold the valves remain open for around 30 seconds as a sort of 'look at me' feature??? No??
With say MRC's quiet start these stay closed (once vacuum is up) and the revs drop very quickly.
Not on my car prior or after visit to MRC for valved miltek and mapping.
Valves only take a couple seconds maximum to close from a completely cold start.