cbgpe

I have the switch to control the muffler valve in the exhaust system
The valve is staying open
I bypassed the switch and put the regular 10 amp switch back in place but the valve still stays open . The valves themselves are mechanically free
Any other place to look ? Is there a relay I should check/ replace ?
Any help would be appreciated
PM would be fine as well
Thanks
CBGPE

kenneyd

Did the vacume lines fall off in the back?

cbgpe

Looked under there and could not see the lines. Will check them in the morning when I can jack the car. Will let you know
Thanks
CBGPE

Vette5.5

Some guy's report a rubber vacuum hose coming lose or breaking off the under hood electric control relay. Not exactly sure where it is, but if it is a leak, you"ll want to get it fixed ASAP, as it can cause your fuel mixture to run lean. You might want to pick up a Mityvac tool, as I've seen these for about $35, complete with the brake bleeding kit. That's chump change, compared to having the dealer diagnose it.

foremaw

Well, the valves always stay open when the car is not running, with or without the M2W switch. Are you saying that when the car is running you cannot close the valves with the switch? Did it work correctly before the switch installation?

cbgpe

I have the switch took it out of the circuit and put in a fuse the valve did not close with the engine running
No problem with the vacuum lines at the back of the car
Anyone have hose routing info ?

Joe_Planet

when mine stayed open the dealer fixed it, it was a leak by the intake manifold in the engine compartment, not by the mufflers... the line just fell off or wasnt plugged in, so check in the engine compartment

Nick 02 Z06

There is also a possibility that the motor that drives the actuators at the rear of the vehicle has gone bad. The part is a about $40. The motor is accessed by taking out the right rear inner tail light. Once removed reach straight down and you will feel the motor and vacuum tubes coming off the motor/module.

One way to check if it is this part is as follows:

Put the the ignition into accessory on mode. Go to the back of the vehicle with the mild to wild remote and push the, "ON" button. If you hear the motor/module make noise like its trying to activate, then your problem is not this part and is most likely a vacuum problem.

Good luck. I currently have the same problem and need to replace this module.

blaine123

If your motor would run dangerously lean with the exhaust valve open would mean you would need a TUNE with a Cat-Back exhaust without the bi-mode. or with an intake. and the Mild to wild kits would come with disclaimers....

The CPU's should be able to adjust for a bit more exhaust flow.

Has anyone done an A/F comparison with flaps open compared to flaps closed with any major A/F issues showing?

I run full time wild with no problems or any noticable Lean or Rich condition.

Mr. Gizmo

Back in the day when we used to say check the "muffler valve" or the muffler valve is going bad that was meant as a joke. And today we are talking muffler valves for real.

mirage2991

yes, on an other forum, there's no difference. What you all need to understand is that this car, at WOT will be in the 11:1 ratio (rich). The ECM does not compensate for back pressure changes, as the O2 are not used by the ECM at WOT (rather the MAF, Vac and other elements). Your O2's are monitored at less that WOT, which then brings your mixture to 14.7:1... in which case, it still wouldn't lean anything as the ECM would compensate, until you reach the pre-defined over correction witch will give you a light...and for that, you're going to need way more than a cat back

Vette5.5

Think we're speaking different language's here. My original reply describes "Joe Planet's" problem a few earlier. The lean condition can be caused when you have an intake track vacuum leak, allowing to much air to be pulled in. The confusion come's in, because the exhaust butter flies are engine vacuum operated. Actually their's an electric solinoid valve at 3500 rpm, then as the intake thottle plates open wider, vaccum drop's, and the exhaust valve's slowly spring back open. I mentioned the MityVac tool, as it work's well for diagnosing vacuum leak's in hoses and actuator's.

AFVETTE

I'm just glad we don't have to worry about those pesky "muffler bearings" any more

Tom

haljensen

Motor? The exhaust flaps are operated by vacuum, not a motor.

Stock;
Flaps open when you first start the car (no engine vacuum)
Flaps closed after engine starts (engine vacuum available)
Flaps open @ 3500 RPM/WOT by shutting off the vacuum to the flaps with an electric switch (no vacuum to the flaps so they're open).

If the flaps stay open all the time you have no vacuum at the flaps from a vacuum leak between the source and the flaps OR the electric switch is blocking the engine vacuum from the flaps.

AFVETTE

Check out this thread, see Talon90's reply about 4 posts down. He presents the GM PP slides that were presented at the 08 C5/C6 Birthday Bash.
http://forums.corvetteforum.com/c6-c...ally-work.html

It's all about VACUUM, or lack there of.

Tom

cbgpe

THE VACUUM LINE BETWEEN THE CONTROL MOTOR/VALVE AND THE VACUUM SERVOS ON THE EXHAUST SYSTEM CRACKED AND LEAKED.
We think this is a fatigue issue ,and not road damage from a road stone or the like. My Z had almost 30 k miles and is an October 05 build car so we may see more of these. These lines flex as the exhaust system vibrates and moves in normal vehicle operation
Hope this helps someone else. Finding the problem was not a cheap date.

Nick 02 Z06

I incorrectly called it a motor/module when I should have said Solenoid. However, per my earlier statment, the part number is: (part # 25794610, listed as Vacuum Valve 7.0 Liter). The Solenoid is located behind the right rear inner tail light. Per my earlier post. If the solenoid is inoperative then the actuators will not open. Vacuum or not.

69 Vette

Where is this electric switch located?