So it turns out, not only is this still coded in the 99 ROM, the hardware is also still installed on a Flash ECU board!
In a stock ROM the Active Exhaust (AE) ONLY effects ECU controlled boost and nothing more. I’ve basically re-writen this entire area of the code to simplify it’s function.
The ecu registers the active exhaust in “sport mode” when pin 75 of the flashable ECU sees ground. This is switched to ground by the AE dash switch in the 91-94 cars. While this switch is missing from the 95+ cars, Adam and I have verified the dash harness is still in place on all VR4s, even 99 VR4s. Installation is quite literally plug and play! ***install write up coming soon***
Pin 7 on the flash ECU is the output for the Active Exhaust controller. (also ties to ground) If you’d like to keep this function in your 91-94 car, make sure your ECU adapter harness has these pins populated. This is a new function for Chrome V2 so chances are, if you’ve purchased an adapter harness, it’s still blank.
If you don’t have a dash switch, but still want to use the AE function for your own exhaust cut out, I programmed a by-pass into the code so the system will still function without one.
The system will only function with bit 13 enabled in periphery 1 and when BOTH TPS and RPM conditions are met. If you don’t disable the dash switch function in the code, the dash switch must be set to tour mode.
Important Note: There was a bug found in the V2 rom. The AE only worked correctly in Tour mode. In Sport Mode the exhaust would always be in quite mode. On 5/31/19 the V2 rom was updated to add the fix for the AE switch. The fix can be corrected on any custom V2 rom retroactively. Just fix the three tables listed in the Active Exahust Catagory.