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MARINE TECHNICIANTODAY | WINTER 2015
W
hether you call it, a “brain box,”
a “black box,” or a “magic
box,” the engine management
module (EMM) is the Grand Central Station
for FICHT Ram, Evinrude DI, and E-TEC
outboard motors since the 2000 model
year. It controls everything to make a low-
emission computer-controlled Evinrude
operate correctly. Gone are the days
when one adjusted idle rpm, fiddled with
carburetor mixtures, and manipulated the
synchronizing of throttle linkages to make
a motor run well. Today the EMM “brain” on an Evinrude outboard is the
equivalent of having onboard a computer engineer, a marine technician,
and a nanny who tattle-tales on you all combined in a single module.
In prior years, and along with other manufacturers, onboard computers
were called Electronic Control Units or ECUs. The major difference is
that an EMM not only monitors and manages the engine operations,
but it also rectifies and regulates the AC alternator voltage, charges
the batteries accurately, and oversees the complex electrical system.
All this administration is contained in one compact unit, unlike an ECU
that would require multiple external modules with additional wiring to
accomplish the same number of duties.
An EMM by itself, as the old saying goes, is dumber than a box of rocks.
It is a collection of logic chips and other electronic components that
cannot do anything unless they are taught (programmed) specifically.
Erroneously called software the operating instructions (programming or
firmware) for each particular outboard are electronically “burned” into the
EMM main logic chip which is equivalent to the BIOS inside your personal
computer. In the marine industry, this firmware or instruction set is also
known as a look-up table or a MAP (not to be confused with the acronym
for Manifold Absolute Pressure). With the EMM programming is easily
updated by using a laptop computer with Evinrude Diagnostic Software
when conditions warrant or as firmware improvements become available.
Motors that incorporate ECUs cannot be upgraded or reprogrammed
without replacing them with a different unit.
To keep the engine compliant with mandatory emission regulations, the
EMM utilizes built-in safeguards to keep them from being reprogrammed
to modify power output and affecting emissions. The EPA is allowed to
administer fines and possible jail time for tampering with emission
controls such as an EMM. The engine serial number and its operating
history are a part of the permanent memory in each individual EMM.
Every fuel injector has a unique identification number determining its
flow characteristics and that along with its cylinder location is also
programmed into the EMM. This is one reason why the EMMs and the
injectors cannot be interchanged between different outboards.
Replacement injectors come with their own unique identification
number to be programmed into the EMM but original injectors from
one motor cannot be programmed into a different motor. In addition
each EMM counts the number of injector pulses during the life of the
motor and slightly adjusts the calibration as an injector wears. This
way an EMM equipped outboard keeps its emission output very low as
TODAY’S TECHNICIAN
By Bill Grannis
Understanding the EMM
& How It Works