Unplugging Exhaust Flap Solenoid

[frankvan]

I've heard a few RS4's with aftermarket exhausts and they sound pretty good but I thought the stock exhaust sounds pretty good when the flaps are open.
So i read a few articles on disconnecting the vacuum lines and plugging them or even one mod where you splice into the ECU harness and trick the ECU in keeping the flaps open all the time when the S button is pressed or adding a "RS4" button and so on.
With a bit of research I located the solenoid that controls the flaps and decided to just unplug it and see what happens. One week later and no CEL's, car runs fine, and I'm happy with the sound, in fact I think it could be still be louder and not annoying. And it's definitely quieter than many of the aftermarket ones I've heard.

FvS

[zachf88]

details of solenoid location? Have you vagged to see if any codes have popped up?

[voidopolis]

The mod is pretty easy to do. I've had them disconnected on mine for for about 2 years - but sealed.

On both exhaust pipes after the mufflers there is a rubber line that goes to the solenoid that controls the flaps. That line is pressurized / a vacuum. To mod; you just disconnect the rubber line from both of the solenoids that close / open the flaps and the solenoid defaults to the open position. make sure you plug up the rubber lines so that you don't cause a leak in the system. Some folks use a golf tee, a cap or a screw and seal it up (I used an appropriate sized screw, a little RTV, and a ziptie on mine). From what I understand the vacuum system is used for multiple controllers, so you really do need to plug it up. The process is easy and reversible. You can still use the "S" button for better throttle response, but the exhaust flaps stay open no matter if you are using sport or not and the byproduct is that you gain a bit more sound. no negative side effects for this mod that I'm aware of, just some added sound.

[frankvan]

The system is behind the left rear wheel in the trunk. If you have a storage bin there simply open the storage bin and remove the floor tray and you'll see a light blue triple sphere vacuum reservoir. The solenoid is mounted to a bracket on top of the reservoir. I just simply unplugged the electrical connector to the solenoid. All my vacuum hoses are still attached - no plugging of vacuum lines with screws or golf tees.

Reply #27 on this thread has pictures (note, he removed the entire trunk liner, but you can access the system through the floor tray of the storage bin)

http://*******************/forum/ind...?topic=3561.25

[frankvan]

Hmm, apparently I can't post links.
It's on ******************* and the topic is "How many parts can I break? - an rs4 build thread by komseh"

[bshanna]

for ~300$ you can do this http://www.forzacomponenti.com/ which lets you control the valves via a key fob (always open, always closed, stock). Reversible, plug and play, etc.

[frankvan]

Hmm, apparently I can't even post audirevolution dot net

[frankvan]

let's try this:

http://s1367.photobucket.com/user/sa...f38c6.jpg.html

- - - Updated - - -

[frankvan]

http://s1367.photobucket.com/user/sa...ml?sort=3&o=13

[skhan91]

does this make a huge difference on stock exhaust with an xpipe? debating doing this but hate mutilating my car haha

[Mr Hyde]

does this make a huge difference on stock exhaust with an xpipe? debating doing this but hate mutilating my car haha

Should sound the same as if you hit the sport button without the wacky throttle response.

This sounds pretty reversible, so you can always go back if you don't like it.

[frankvan]

A couple of pictures showing the location and access to the solenoid.

https://goo.gl/photos/tghY37sFVdRCnBhWA
https://goo.gl/photos/V2j3QtuFi695Q9cb6

[Nathn13ngp]

Hi, has this solution still not come up with any check engine lights etc? Any issues arisen since you did it? Is the secondary vacuum chamber used solely for the exhaust valves or is it used elsewhere in the system?

[frankvan]

Looking at the photobucket picture in post#9 above it looks like the vacuum reservoir only supplies the exhaust flaps.
And so far no CEL's. Also the noise doesn't drone inside the cabin at highway speeds either.

[Avussilver07]

I just did an X pipe in place of the resonator, on Monday in fact and I think it sounds great. Maybe a little raspy in the low RPM range but overall I love it. the flaps on mine are stuck open due to some corrosion on the rods they pivot on. So I am just leaving them stuck open until I do aftermarket mufflers.

[voidopolis]

Hi, has this solution still not come up with any check engine lights etc? Any issues arisen since you did it? Is the secondary vacuum chamber used solely for the exhaust valves or is it used elsewhere in the system?

No issues with CELs or other problems on my car. Just plugged up the holes in the rubber tube and it was done.

[WinterRunner]

This solution is soo much cooler and elegant than the "golf tee mod", wish I knew of this before now...

[d2a4]

Looking at the photobucket picture in post#9 above it looks like the vacuum reservoir only supplies the exhaust flaps.
And so far no CEL's. Also the noise doesn't drone inside the cabin at highway speeds either.

I unplugged it today. Look like it also run up front, correct?

[DASH!]

Unplugged solenoid for a couple of weeks now. No issues. Car is easier to drive as the acceleration is more linear particularly in 1st and 2nd gears so will be leaving it unplugged.

Btw, it's trickier to access the solenoid for avants as the interior sidewall needs to be unclipped.

Also, I plan to make an effort to clean the exhaust with every car wash to hopefully prevent carbon from seizing up the valves.