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SYSTEM ANALYSIS
EXHAUST VALVE (V4 MODELS)
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 posi-
tion of the exhaust valve provides optimum
exhaust tuning for various running conditions. At
slower speeds and under acceleration, this sys-
tem 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.
Refer to EXHAUST VALVE RELAY TESTS on
p. 152.
Use the Evinrude Diagnostic Software program
for “static” test of actuator motor.
Exhaust Valve Diagram 005434
SLOW SPEED
HIGH SPEED
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