Exhaust by-pass valve controlled by what?

I just had a new ECU put in my 5.2 355 and immediately noticed a change in the exhaust sound when the rpms got over 5k. I assume this is the by-pass valve opening up. Oddly enough I have never noticed such a difference in the exhaust decibel level as I do now and am beginning to think that the valve may not have been opening in the past. Could replacing the faulty ECU be responsible for the valve now opening? The only other work that was done was a factory campaign 148 which replaced the OBDII connector wire and pin.

 

ECU for what? There is the Motronic ECU, catalyst ECU's, suspension ECU, etc. The Motronic ECU which controls the overall engine management, does directly control the exhaust valve operation as well. What required replacement of this ECU?

 

The catalyst ECU

 

Engine vacume opens a 355 by-pass valve, there is no electrical trickery involved. Some times they dont open because there can be s simple split in the short rubber pipe that conects to the by-pass valve.

 

There are valves that are electronically controlled. See my thread: http://www.ferrarichat.com/forum/showthread.php?t=230192
I unplugged the electrical connectors, cleaned them, and all was good.

 

Indeed Zero! ............ engine vacuum provides the muscle ............... though the engine vacuum is rationed by a solenoid valve controlled by the engine ECU ...........

Though on the 360, it may be controlled by engine vacuum alone .......

 

Back to the original question .... Will just replacing the catalyst ECU affect the opening and closing of the bi-pass valve? Something caused the valve to start opening and that was the only thing that was done.

 

is this true, the 360 doesn't have a vacuum reserviour tank or a solenoid valves to modulate the vacuum supply?