If you listen carefully when letting off the gas in dynamic mode (and/or with exhaust button pressed) are you able to hear the exhaust solenoid activate and the exhaust valves open just before you get the snap, crackle and pop?

I hear a faint but distinct noise coming from the rear of the car when I let off the gas after a reasonably high Rev and assume it's the solenoid and/or exhaust valve (s). Top down on the vert so maybe this is more noticeable compared to a coupe.

Is this what I am hearing or is something else going on? And is it normal to hear this or is there a problem.

 

I can't hear any such thing in the Coupe.

 

The exhaust valves aren't opening and closing when you're letting off the throttle in dynamic mode. They are full open all the time in dynamic mode, unless you close them with the button.

 

Thanks! So this rules out the solenoid/valves. The sound is only and always reproduce able when letting off the gas after revving to about 4.5k (using paddle shifters) and it's very faint but noticeable. Sounds like a tire rubbing while rotating 2 times but I know it has nothing to do with the tires, just using it as an example.

And it never happens when in the regular mode or without the exhaust button pressed. It's very quiet.

When I have it in for service I'll have them look at it - easy to reproduce. Wonder what it is?

 

Sorry for replying to my own reply. Just came back from a spin.

Started in paddle shifter mode with loud exhaust and it makes the noise in 2nd gear, after taking foot off the gas when up in the 4k rpm range and does it for a second before you hear the exhaust crackle.

I tried in 3rd gear but wind noise was too much at that speed/rpm to hear if it does it.

What's weird is that while in paddle shifter mode I then turned off loud exhaust and it was quiet as expected and did not make the noise in 2nd gear. I then hit the loud exhaust button and even in 2nd gear coming down from 4k it did not make the noise. Tried several times and noise was gone.

We'll see if next time I start out with loud exhaust in PS mode if it makes the noise. My bets are yes.

 

Taking it in for service next week and suspect this is the cause:

Active Exhaust Vacuum Pump Noisy ? 2014-2016 Jaguar F-TYPE | jlr.oemdtc.com

 

The video Ryan23 posted replicates the strange sound I have been hearing from my exhaust at 21 seconds, 38, 114 and 124. You hear a faint noise, like a tire rubbing 2 rotations and this is exactly what I hear in my V8. I am listening to the vid using headphones.

It's in the shop for an oil change and to diagnose the noise. Tech called to say they are installing a new muffler and I'm curious to hear what was wrong with mine, if the sound I hear is in fact a problem and if the new muffler will fix anything.


What do the forum experts think?

 

In another thread a I mentioned I was getting a "chirping" noise from the rear occasionally and that the exhaust didn't appear to be switching loud to soft.

Upon driving the car today, having been left for 10days at least one of the exhaust vales stayed stuck for at least 45minutes/40 plus miles.

It did eventually close when I decided to explore the upper rev range , but later in the day having kept switching the exhaust loud to soft to test the system, it stuck again

Have had similar issues in the past with motorbikes and sticky exhaust flaps unfortunately this seems more of the same.

Booked into dealers week Monday.

 

I must be stone deef! I can't hear anything but combustion sound.

 

Unfortunately I can hear it when driving the car too. Very annoying.

 

I've heard the noise of the vacuum pump in a couple of cars, but only from the inside, when i've been in the passenger seat (left seat of RHD car, so drivers seat in LHD car) over my left shoulder, a whirring sound during decelleration.

I don't know what it sounds like from the outside, it's not what i would have thought from listening to the video...

But what i've heard from inside the car is the vacuum pump, which is the subject of that TSB to remove the pump and connect a new vacuum line to the intake manifold to operate the valves instead.

 

I had initially thought it might be the vacuum pump but after hearing the dealer is replacing my mufflers I don't think it was the culprit. I'll update once we get the car back.

 

This is not true on my MY16. My valve are opening and closing in dynamic mode. They close near idle and open maybe 1.5k rpm. At least mine does.

 

I have a 16 also, and when in dynamic mode (99% of time, unless I see a cop) the valves stay open just as Stohlen said.

 

Then my car exhaust has an issue. The valves on my exhaust close automatically near idle rpms and only open when I hit the accelerator. When stopped my valves are closed even with the active exhaust on. I'll see if I can film it for you guys.

 

Anyone have the active valve operations description? Is the vacuum applied to open the valves, or to close the valves. If to open, then zmoothg may have a mild vacuum leak. However, I believe the operation works the other way around since the valves are always open on start up (vacuum not yet built up).

 

Here is a clip of the functionality of my valves with active exhaust switch on. Guessing this is not normal. I have a closed valve at low RPM when in loud mode.

 

Vacuum is used to close the valves. If you remove the vacuum, the valves stay open.

Yeah that's not how they are supposed to work...

Have a look at the explanation here;



What i can tell you is that the opening/closing of the valves is part of the PCM program (Powertrain Control Module) otherwise known as the ECM, or ECU...

You have an aftermarket tune in your car? You need to talk to your tuner, not the dealer.

 

So I did some more experimentation and realized it's not a problem with the VAP TUNE. I even reverted back to the stock tune to confirm. Basically this is the behavior when dynamic mode is off but the active exhaust is on. When I have dynamic mode on and active exhaust on the valves stay open constantly.

I did find my passenger side valve does not open completely, only about 50% open, the driver side is fully open.

Seems I do have some issue with the exhaust. When the valves are closed it sounds like something inside the muffler chamber is vibrating / rattling as you can hear in the video. I don't think the sound is coming from the valve itself. Very strange.

 

https://www.dropbox.com/s/szc3vze5ol...haust.pdf?dl=0