Active exhaust
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I see you recently joined the forum. It would be helpful to know what year XKR you have or are looking for. You can note that in your signature.
Active exhaust is standard on 07-up XKR models. When activated, it works like an exhaust cut-out valve, bypassing the muffler for less restriction and louder exhaust note.
There has been a lot of discussion about the XKR active exhaust. Using Advanced Search for "active exhaust" under current models XK XKR resulted in 75 threads. Not sure if this link will work: Jaguar Forums - Jaguar Enthusiasts Forum - Search Results
How does Active Exhaust work? See this thread, in particular Post #7 by jallitt, for details (07-09 4.2L XKR): https://www.jaguarforums.com/forum/x...se-19-a-62736/
You can also pull Fuse 19 to keep the muffler valves open all the time.
Active exhaust is standard on 07-up XKR models. When activated, it works like an exhaust cut-out valve, bypassing the muffler for less restriction and louder exhaust note.
There has been a lot of discussion about the XKR active exhaust. Using Advanced Search for "active exhaust" under current models XK XKR resulted in 75 threads. Not sure if this link will work: Jaguar Forums - Jaguar Enthusiasts Forum - Search Results
How does Active Exhaust work? See this thread, in particular Post #7 by jallitt, for details (07-09 4.2L XKR): https://www.jaguarforums.com/forum/x...se-19-a-62736/
You can also pull Fuse 19 to keep the muffler valves open all the time.
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jagtoes (10-29-2013)
#4
Specifically, the two outer pipes of the quad-pipe setup on the XKR bypass the rear muffler box and are controlled by a flap which is open below 1100 RPM and above 4000 RPM. In between, it closes in order to push all the gasses through the muffler to keep the noise down. However, on the 5.0L models, if you select manual gear change using the paddles, the valves open.
#5
Specifically, the two outer pipes of the quad-pipe setup on the XKR bypass the rear muffler box and are controlled by a flap which is open below 1100 RPM and above 4000 RPM. In between, it closes in order to push all the gasses through the muffler to keep the noise down. However, on the 5.0L models, if you select manual gear change using the paddles, the valves open.
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From the workshop manual:
So, based on that, Sport mode doesn't open the valves, only manual shifting.
When the transmission is in the manual (sequential shift) mode, the exhaust valves are permanently open. When the transmission is in the normal or sport mode, the position of the exhaust valves depends on engine speed and load
#7
I always thought that by selecting the "S" mode the valves opened. However, the valves open permanently when "S" mode is selected and a paddle shifter is depressed. If a paddle is not depressed then the valves remain closed and behave according to the chart (based on rpms and throttle depression %). Based on this when a large gear number appears on the LCD the exhaust valves are open (sequential shift, manual mode, is engaged). Consequently, no need to remove fuse 19.
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#8
I always thought that by selecting the "S" mode the valves opened. However, the valves open permanently when "S" mode is selected and a paddle shifter is depressed. If a paddle is not depressed then the valves remain closed and behave according to the chart (based on rpms and throttle depression %). Based on this when a large gear number appears on the LCD the exhaust valves are open (sequential shift, manual mode, is engaged). Consequently, no need to remove fuse 19.
Loth
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Loth
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JAGUAR XK - XKR 2006 - 2012 WORKSHOP SERVICE REPAIR MANUAL - X150
A lot of useful stuff in there...
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amcdonal86 (11-01-2013)
#17
The 4.2L XKRs do not take the transmission mode into account as do the 5.0L XKRs. Compare the 2 charts posted by Ngarara, above.
If you want the active exhaust to stay fully open below 4,000 RPM and under light throttle simply remove Fuse 19.
Stuart
Last edited by Stuart S; 10-31-2013 at 09:45 PM.
#18
The XK's exhaust is "active" also, but differs in that the valve assembly is spring loaded. The muffler is tightly sealed and there appears to be no way to access the spring assembly for either repair or modification. Has anyone peeled back the sheet metal of the muffler to access the valve assembly?
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