496 HO Guardian Mode
 

Problem...at approx 4K RPM my '03 496 goes into guardian mode...but only when the Corsa exhausts are open. No guardian mode when closed. I replaced what I thought was a bad solonoid (seemed to not open fully). I still have the problem. Any thoughts out there?

Might be a voltage issue. The Corsa pulls a lot of current. Check it with a scan tool. It should tell you why it's going into guardian.

Are you sure you are actually seeing a "guardian mode. You need to hook up a scan tool BEFORE you use the boat again and see what codes are active and what if any guardian event is logged. Are you hearing any beeps from the alarm at that point to indicate a fault code activation?
You may want to make sure your captains call-quick & quiet flaps are really opening before 4000rpms because the back pressure if they are closed at that rpm could hold the motor back at 4000rpms and do some pretty nasty engine damage if run at that rpm for any lenght of time!
I would suspect at this time that your problems may be more exhaust system related than engine. Hope its a minor problem and fix. good Luck

Regards,
Ray @ Raylar