Active exhaust at idle?
- Thread starter maddog1982
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Anonymous
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Just to add to my earlier post in this thread re my MY20 P380 V6. Pressing the exhaust button at idle opens the valves and there is a noticeable increase in exhaust noise, I have watched the valves open. Then, as soon as the throttle is opened the valves close and the noise diminishes until around 3500 rpm when they open again. I guess this is all controlled by the ecu. I tried pulling fuse 15 and valves did stay open but just too noisy for where I live.
I have now fitted a valved cat back system which has a remote control for the valves so I control the noise level, not the ecu. It occurs to me that you could just install the remote control vacuum pump with the OEM exhaust and it would then stop the ecu over-riding the active exhaust switch position. The remote vacuum pump was supplied by Viezu. Been on for a while now and no issues.
I have now fitted a valved cat back system which has a remote control for the valves so I control the noise level, not the ecu. It occurs to me that you could just install the remote control vacuum pump with the OEM exhaust and it would then stop the ecu over-riding the active exhaust switch position. The remote vacuum pump was supplied by Viezu. Been on for a while now and no issues.
A few of us from this forum discussed this issue at Beaulieu last year and to the annoyance of one of the marshal's, we watched the valves operate through the rev range.
That f type was a 2019 SVR which did sound loud on start and with the active exhaust switch activated we observed exactly as described by Gus A
GusA wrote
Just to add to my earlier post in this thread re my MY20 P380 V6. Pressing the exhaust button at idle opens the valves and there is a noticeable increase in exhaust noise, I have watched the valves open. Then, as soon as the throttle is opened the valves close and the noise diminishes until around 3500 rpm when they open again. I guess this is all controlled by the ecu. I tried pulling fuse 15 and valves did stay open.
On this later car pulling fuse 15 in the engine bay fuse box left the valves permanently open as Mickjaguar describes earlier in this thread. (I can only assume the electronic control is disabled by doing this leaving the valves open by default.)
Earlier cars 2017have the active exhaust as fuse 43 in the passenger footwell fuse box.
I believe the resault of having the Jag software updates ( drive by noise) produces this effect on earlier cars they are muted in the lower revs by the valves remaining closed.
Which is probably the rev range for most mundane trips.
You get the start up feel good noise at idle and when your giving it the beans past 3000 rpm.
Pops and crackles not affected in earlier cars either.
View attachment 1
That f type was a 2019 SVR which did sound loud on start and with the active exhaust switch activated we observed exactly as described by Gus A
GusA wrote
Just to add to my earlier post in this thread re my MY20 P380 V6. Pressing the exhaust button at idle opens the valves and there is a noticeable increase in exhaust noise, I have watched the valves open. Then, as soon as the throttle is opened the valves close and the noise diminishes until around 3500 rpm when they open again. I guess this is all controlled by the ecu. I tried pulling fuse 15 and valves did stay open.
On this later car pulling fuse 15 in the engine bay fuse box left the valves permanently open as Mickjaguar describes earlier in this thread. (I can only assume the electronic control is disabled by doing this leaving the valves open by default.)
Earlier cars 2017have the active exhaust as fuse 43 in the passenger footwell fuse box.
I believe the resault of having the Jag software updates ( drive by noise) produces this effect on earlier cars they are muted in the lower revs by the valves remaining closed.
Which is probably the rev range for most mundane trips.
You get the start up feel good noise at idle and when your giving it the beans past 3000 rpm.
Pops and crackles not affected in earlier cars either.
View attachment 1
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So I’ve pulled out fuse 15 after talking to a guy at Gaydon last weekend at the F type meet. It’s a Reims 450 v8 my21
It makes a huge difference, it snaps and crackles on demand - no warnings or errors. While it sounds great I’d say it’s given it a slight lag on hard acceleration.
I’m going to run it another week without and then pop it back in for some comparisons.
Anyone else with a my21 v8 experience with fuse 15?
It makes a huge difference, it snaps and crackles on demand - no warnings or errors. While it sounds great I’d say it’s given it a slight lag on hard acceleration.
I’m going to run it another week without and then pop it back in for some comparisons.
Anyone else with a my21 v8 experience with fuse 15?
SilverDreamMachine
New member
Buzz450 said:
Thanks for the info. I'm struggling to see how changes to the exhaust would create lag on acceleration unless this is also affecting the ecu in some way?
I have a 2021 P450, tuned by Viezu admittedly, and ive not noticed a lag in acceleration or response since pulling fuse 15. If, as SCM, suggests the gearbox has learnt your driving style it can be reset by turning on the ignition when first entering the car (dont turn start the engine) and holding the accelerator flat to the floor for 30 seconds . Turn off ignition and the reset has been done. It's been this way to reset the learning of the ZF gearbox for at least 16 years (used to do it on a 2007 bmw 630i).