RoadtripRyan

Hi everyone,

I have a 2005 C2S with the OEM sport exhaust. However it has the issue, as many 997s with the original sport exhaust now have, that the sport exhaust stays silent. When I start the engine the sound is loud for a moment and then gets quieter. I have confirmed this by checking the vacuum boxes (not sure what the correct term is?) under the car. Since the car has the sports chrono package and the sport button, it should open the exhaust in the higher revs when above 45 mph and in sport mode, which doesn't happen. (Not sure if this restriction is only for german vehicles?) I assume the vacuum tubes have no holes, since the system stays closed/silent all the time. Also when i disconnect the Y-tube on the valve, the car is instantly louder. I have replaced the valve where the tubes connect, but that did not help. From my knowledge the only thing that remains is the electric cable connecting to the valve. How can i test this while I'm not driving? Or are there other parts that could be broken?

thanks in advance
Ryan

krazykarl

The change-over valve is supposed to be closed when sport mode is disabled. Have you tried disconnecting the connector to the valve to see if it goes loud? If so, it appears a signal is being sent to open the valve even when the sport button is lit.

RoadtripRyan

So if I understood that correctly, I should park car with engine running, enable sports mode and then remove the electric connector from the valve?
Will do that tomorrow, but just in case it happens to be the case, what could be the reason for that? Can I diagnose that?

krazykarl

If you pull the connector, under normal operation it should remove any signal and force the change-over valve to its default position of closed. This will open the flaps in the PSE and make the exhaust louder. As to why it would always be sending a signal to open the change-over value, I am not sure. I don't think its something that could have been coded by a previous owner.

Petza914

The muffler valves use vacuum released from the electric solenoid to pull the valves closed for quiet mode. Without vacuum being supplied to the muffler valves, the springs in the valves should push them open into sport mode. If the valves are in proper shape, without vacuum being supplied, they can be physically moved by hand in the opposite direction of the spring pressure, just like if vacuum was being supplied. If with the car not running you can't move the rod on the valve by hand, something is stuck and then neither the spring nor the vacuum will be able to properly operate the muffler valves.

If you can move the valves by hand, next thing to check is the vacuum solenoid. Is it supplying and removing vacuum to the hose that feeds the muffler valves when the button on the dash is pressed. If it is, then your issue is with the lines going from the solenoid to the valves. If it's not, then the issue is with the solenoid itself or further upstream. You can test the wiring to the solenoid with a meter. Does pushing the dash button change the voltage at the solenoid plug. If so, then your solenoid has failed. If not then keep going upstream. Does the light on the button change state when the button is pressed? If not, you have a fuse or wiring issue. If it does, then you have a wiring issue between the button and the solenoid.

RoadtripRyan

As suggested, I did some tests. When parked, but with engine running, removing the connector from the solenoid switches the car to rumbling loud. I also measured the voltage that is supplied to the solenoid:
0V is supplied when the car is off.
With keys turned (but engine off), 12 V is supplied.
Engine on is ~13-14V.
Sport mode active also ~13-14V.
So the voltage never drops and the solenoid always keeps the valves closed.
Otherwise the sport button seems to work. Light is shown when its pressed, Sport mode is shown in the instrument cluster and the throttle response is sharper. PASM Sport is shown, but I feel no difference. Maybe its due to the Techart Lowering Coils that the previous owner installed (too hard and too low).


I also checked for DTCs using my Foxwell Diagnostic (Translated from german, so might not be the exact same message in english):
PSM - 4444 - Steering Angle sensor not initialized
PAS - 8004 - lower limit exceeded - Terminal 50
PAS - 8001 - lower limit exceeded - system voltage
PASM - C203 - Error, control unit for steering wheel electronics (drive)
POSIP - C152 - communication PSM control unit (drive)

Nothing too serious from my understanding, mostly related to issues that could occur when the battery is changed. I found some threads in this forum that relate the PASM error to faulty cables/plugs. I will try to investigate on this error...

RoadtripRyan

Short update on my side:
I checked all the cables and found that the previous owner made some changes to the sport exhaust system. The grey/green cable from the DME was cut and soldered to a switch near the fusing box. Thereby it is possible to manually override the signal normally originating from the DME. The green/grey cable can be pulled to ground, which closes the circuit and applies the direct DME voltage (red/blue cable) to the solenoid valve. From what i have investigated in the wiring diagrams, it's not as the original sport exhaust would have been connected, but still a simple "fix" to enable the same functionality.
However there is one unfortunate issue: The valve gets burning hot even after just a few minutes. And i mean really hot!
Im not sure this is intended, or rather due to the "hack" they did and probably forgot some resistors?

Could someone with original sport exhaust system please measure the voltage and amps on the solenoid plug when the sport exhaust is active?
I'd like to compare these values with my system.