EXHAUST VALVE (V4 MODELS)
The inner exhaust housing on Evinrude E-TEC V4 models is designed with an adjustable “tuning” length. Two modes of exhaust gas flow are accomplished through the use of an exhaust valve. A control module and actuator motor are used to move the valve. The EMM controls the
position of this valve which opens and closes a chamber in the inner exhaust. Switching the position of the exhaust valve provides optimum exhaust tuning for various running conditions. At slower speeds and under acceleration, this system opens a longer path, allowing the engine to develop more midrange horsepower as the boat comes on plane. At higher RPMs, the path is shortened for maximum high speed performance. Refer to Exhaust Valve Diagram below.
Exhaust Valve Diagram 005434
Refer to EXHAUST VALVE RELAY TESTS on p. 152.
Use the Evinrude Diagnostic Software program for “static” test of actuator motor.
