Blueline

Hey guys, I need to find the solenoid that operates the exhaust actuators on the 2007 RS4. They have constant vacuum with the S mode on or off. Im guessing the solenoid crapped out and I need to chaneg it. If I unhook the vacuum lines the baffles open and I can feel constant vacuum regardless of the S mode button.

I would just leave them unhooked, but the new buyer for my car wants it to function as designed. Someone please help me and tell me where to find that solenoid that controls the vacuum to the rear baffles.

Thanks in advance!!!

ELEVENS

According to the Bentley manual, left luggage compartment. From the photo it looks like it's attached to the vacuum canister assembly. Let us know if you find it, I'd like to know too! Good luck.


Work sequence

• Let engine run briefly so that the required vacuum for the test is present in vacuum reservoir.

• Switch off engine and connect Vehicle Diagnostic, Testing and Information System VAS 5051 and select vehicle system "01 - engine electronics" . Thereby, the ignition must be switched on.

• Display on VAS 5051 :

• In selection - 1 - , click on the function "03 - output Diagnostic Test Mode (DTM)" .

• Tap button until Left Front/Right Rear Electronic Differential Lock Intake Valve N321 - arrow - at left in luggage compartment is activated

Operating rod - arrow - for exhaust flap must move back and forth at both rear mufflers.

• If actuator rod does not move:

• Check exhaust flap vacuum reservoir Exhaust flap vacuum reservoir, checking .

• Check vacuum line to vacuum reservoir and to Exhaust Flap Valve 1 N321 under left side trim in luggage compartment.

• Check Left Front/Right Rear Electronic Differential Lock Intake Valve N321 and using "Guided Fault Finding" .

• End function "03 - output Diagnostic Test Mode (DTM)" by pressing button.

• Select "06 - End Output" .

• Switch off ignition.

Blueline

Thanks for the quick reply!!! So would that's an pull all the carpeting in the trunk and it should be behind the little black storage compartment on the driver side? Thanks for your help if not it has to go to audi, but I would rather fix it myself. Can you narrow the location down for me? Very much appreciated!!!!

Blueline

Ok I got it apart. With the s mods on I get power and no ground at the plug. With the s mode off I get power and ground at the plug. I'm assuming that's the correct signal from the ecu?

Does this mean the valve / solenoid is bad?

Blueline

Hey guys just an update in case anyone searches for this in the future. The Vacuum reservoir and the solenoid which opens and cuts vacuum to the baffles is located behind the black storage compartment on the driverside in the trunk. It takes a few minutes to get everything apart.

For mine, I was able to test for signal coming from the ECU when the S button was depressed. What it does is actually give the solenoid a ground when the button is activated.

So once it has the 12v constant, then the ground when the sport mode is activated it actually releases the magnetic field in the solenoid allowing a spring in there to push a plunger forward blocking off the vacuum going to the baffles. When you switch the S mode off, it activates the magnetic field again, by taking the ground away and pulling the magnetic plunger back into the solenoid allowing the vacuum to close the baffles.

I hope this helps someone in the future!!

Thanks guys!

ELEVENS

Thanks for posting that. Nice to know, and good to be able to search for it later if needed. So you did you fix the problem?

ELEVENS

Well well well now my solenoid valve quit working. I ordered a new one - $150 !! %**@@@!!( All fixed now.

I've learned something that runs contrary to popular "forum wisdom". Regarding the popular mod of pulling off the vacuum hoses to the muffler valves: I've read numerous posts and even experts claiming that when doing that mod, make sure that you plug the hoses or the car will suffer massive vacuum leaks and will run like poo. That little issue is also cited as something to check when the car is not running properly....

Well guess what? When the Sport button is "on", the solenoid valve vents the vacuum to ATMOSPHERE. In other words, a huge vacuum LEAK That's right. Conversely, with Sport off, the solenoid is closed and does not allow a leak to atmosphere, which the applies vacuum to both muffler valves and pulls the butterflies closed.

I'm going to view this as a $150 course in RS4 muffler valve design, operation and troubleshooting. You should still plug the hoses though, just to keep dirt out. But leaving the vacuum hoses unplugged should not cause any drivability problems.