07AOZO6

Hi Guys,

First I would like to say I do have an understanding of how the system is supposed to work, thank you to all the guys who have posted on this subject in the past.

A few weeks ago I noticed that the exhaust flaps would open at random, during normal cruising, idling, after a few mins of driving or an hour or more of driving. (I understand they are supposed to open above 2800 or 3500 depending on how aggressive you are driving etc).

Sometimes they would open on the way to work and stay open, then when I left work they would close and stay closed all the way home unless I goosed it, in another words, they functioned as they should.

I had the M2W in and it would work perfect as well except when the flaps stuck open.

Yesterday we went for a 200 mile drive and the flaps worked as they should all the way. Then suddenly while leaving a stop light they opened and remained open all the way home (another 200 miles). This morning they remained open after I started the car.

Figured the M2W must be toast so I removed it and installed the 10 amp fuse, started up the car and the flaps closed, great!

Went for a drive, had not even left the complex when they opened up and remained open. Obviously the M2W was not at fault.

I checked the vacuum lines, traced them from the actuators on the mufflers to the solenoid behind the tail lights, all good. Then I pulled the wiring connector off the solenoid and started the car, flaps remained open. I can push on the actuators and the flaps move freely.

I traced the vacuum line from the solenoid as far as I could (it runs up above the trans) and it all looked good.

My car is an early 07 model year built in Aug 06 with 28k miles, has headers, high flow cats, x-pipe, the muffler mod and tuning. Everything functioned as it should till the recent past.

If anyone has already been thru this can you share the outcome please.

VNAMVET

......at 21,000 miles my Z exhibited the identical same problem.........dealer replaced actuator module ( I believe this is the nomenclature) and problem solved!

Nick 02 Z06

Last thing to check: Run a separate piece of vacuum line up directly to the actuator itself (one at a time) and suck it closed. One of the actuators may have a diaphragm thats not properly seated. It may be seating part of the time but not all the time. If one of the diaphragms goes bad, neither will work. Good luck troubleshooting the issue. Nick

RoatanMan

No issues with mine... I leave the flaps open around town but on the freeway I keep them closed to eliminate the drone at low RPMs...

FYI: Flaps open at 3500 rpm unless you are in comp mode where they open at 3000rpm...

TAILWAG

you should still be covered under the bumper to bumper...take it to the dealer as most likely your actuator/s went bad...

07AOZO6

Thanks guys, I will check out the actuators as described above with some vacuum hose.

My car is now 4 years old to the day actually so the bumper to bumper is done.

Any other ideas if the actuators are good?

07AOZO6

Any idea, where the actuator module is located? Do you have a part #?

Thanks!

foremaw

With both of them opening, it would seem unlikely to be an individual flap mechanism problem or a single vacuum line leak. There may be an issue with the vacuum source. I believe there is also a solenoid behind the right inner tail light that operates as a system actuator and a system control module. Since these are rpm actuated, maybe there's an issue in one of those systems. Someone who knows more about those systems might be able to add more.

GOLD72

Rear mounted system actuator/control module. That's what I think has become a problem on my car. The past couple of months both butterflies will suddenly open after the car warms up good and then stay open for miles until I turn the car off. Last spring it would do this maybe once every 6 weeks or so. Now it is very consistent about opening sometime after the car appears to warm up. Never within 10 minutes of startup. I am covered under GMPP but I have been in no rush to get it fixed.

CB1953

Also check the lines closely....I had one that had become brittle and was leaking, but you could not tell by looking at it. When it was touched, it kind of crumbled and fell apart.

Nick 02 Z06

FYI, if one actuator goes bad, or one vacuum line to an individual actuator goes bad, neither one of them will open. The vacuum comes from a single sorce and splits on the backside of the rearward solenoid behind the right side tailight assembly.

If you were closer, I would swap in my extra solenoid to see if that is the problem. Again, good luck with repairing your issue. I had this happen and it ended up being pretty simple to fix. Unfortunately, I figured it all out the hard way.

JoesC5

I think you meant "closed" instead of "open". The valves are spring loaded to hold them open and it takes a vacuum to close them. You lose the vacuum and they will revert to the "open" position.

Nick 02 Z06

You're right, I meant, "CLOSED". Good catch! I was in a hurry. Thanks! Nick

Autodude

Had same problem a couple of weeks ago.. popped hoop heard vacuum leak come to find out it was the vacuum line that runs from trans tunnel over brake booster line was split where the lines join..fixed !

C5Lion

I had something strange happen to me after a track event last weekend. I am getting an annoying load exhaust groan when I accelerate from 1500 RPM to roughly 2000 RPM. Very noticeable in 4th through 6th gear. Once I get above 2000 RPM it gets quiet again. It would seem to me than flaps are opening and then closing again.

Any ideas?

fst1

I've never heard that the comp mode effects when the flaps open. Can somebody confirm this?
FST1

C5Lion

comp mode opens the flaps at 3000 rpm

DaOtherOne

Could be a broken baffle in the muffler.

Once mine warm up I get a rattle in one between 1500 and 2000.

C5Lion

Do you get a load drone at these RPM's? Does it go away once above these RPM's?

smez2

Did you say that if one of the diaphrams goes bad neither valve will actuate? So both exhaust are open? My wife's '08 is doing the same thing. It has 18,000 miles on it.