3 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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YOUR RESEARCHSports Exhaust Valve Issue
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valves
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Suspected cause · Original poster
Since the electrical connection was gone, I assumed this was due to faulty valves.
Leading evidence: 'valves' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'valves' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check smooth operation of your valve' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
If it does, then proceed to lube and check the smooth operation of your valve to make sure it is not binding in any way.
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Suggestion
If that doesn't work, you will have to test the diaphragm to make sure it's holding vacuum.
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Outcome without a verified action link
This worked for a while...however, last year the valves seemed to close on their own, intermittently.
Hey All,
I tried to post this last night, but it appears to have gotten lost...if it shows up, go ahead and delete one of these.
The problem:
I believe the vacuum system for the muffler bypass valves is faulty.
The car:
2002 C2, 70k miles
XLF Sports Exhaust (I think)
The background:
The car came with sports exhaust, which I believe has option code XLF. It has the muffler bypass, with solenoid valves, but no dash button. When I bought the car, it was loud 100% of the time. This is how I assumed it should operate. After about a year, it would "go quiet" intermittently. The internet taught me this is how it is supposed to operate - to be quiet between 30 and 45 mph. It would only be quiet occasionally, but it was enough to annoy me, so I performed the relay mod (pulled the resister from 996.618.980) so that the valves would fail open all the time - loud would be default.
This worked for a while...however, last year the valves seemed to close on their own, intermittently. Since the electrical connection was gone, I assumed this was due to faulty valves. Then I started to notice that it was only quiet during HOT, SUNNY days (95 degrees and up) when it was parked in the sun.
Since the mufflers are some of the hottest parts of the car, and since the car goes FULL QUIET, not HALF quiet (i.e. only ONE valve closing while the other one stays open), I'm lead to believe this is an issue in the vacuum system which actuates the valves.
Does anyone have any insight as to how the vacuum system works and or how to fix it?
Thanks!!
As you found out, the default setting without any vacuum is loud, meaning if you removed both vacuum wires from the mufflers, they would be on the loud mode all the time.
The vacuum is centrally fed via a T in the vacuum line so if it was vacuum related, they would both act the same.
This leads me to believe that one of your actuators is on it's way out. Either the diaphragm is partially torn or there is enough corrosion in the actuator arm and valve as to not maintain operating consistency.
You can try spraying WD-40 around the actuating arm for starters and see if the arms are corroded. If that doesn't work, you will have to test the diaphragm to make sure it's holding vacuum. Compress the actuator all the way, remove the vacuum line that goes into it and plug up the port with your finger and see if the diaphragm holds. If it does, then proceed to lube and check the smooth operation of your valve to make sure it is not binding in any way.
What else runs off the vacuum?
I'm pretty sure it's vacuum related as both valves would close together, both before the relay mod, and now, for whatever reason, in the heat.
The actuating arms move freely, and you can hear the diaphragm of the solenoid popping. They're probably not in the best of shape, but they still work enough to close the valves on vacuum. Just don't know how the heat (or ?????) is causing the vacuum.
This is a source reference. Confirm exact model applicability in the original material.
