G643(E) Service Manual
Chapter 5. Engine Management System (EMS)
151
• Fixed-speed isochronous governing with three
switch-selectable speeds
• Fuel enrichment and spark timing modifiers for
temperature and fuel type
• Transient fuel enrichment based on rate of change
of TPS
• Transient wall wetting compensation for gasoline
• Input sensor selection and calibration
• Auxiliary device control for fuel pump, fuel lock-off
solenoid, tachometer, MIL, interlocks, vehicle
speed limiting, etc.
• CANBus data transfer for speed, torque, etc.
Other system features include:
Tamper-Resistance
Special tools, equipment, knowledge, and
authorization are required to effect any changes to
the MI-07 system, thereby preventing unauthorized
personnel from making adjustments that will affect
performance or emissions.
Diagnostics
MI-07 is capable of monitoring and diagnosing
problems and faults within the system. These
include all sensor input hardware, control output
hardware, and control functions such as closed-loop
fuel control limits and adaptive learn limits. Upon
detecting a fault condition, the system notifies the
operator by illuminating the MIL and activating the
appropriate fault action. The action required by each
fault shall be programmable by the OEM customer
at the time the engine is calibrated.
Diagnostic information can be communicated
through both the service tool interface and the MIL
lamp. With the MIL lamp, it is possible to generate a
string of flashing codes that correspond to the fault
type. These diagnostics are generated only when
the engine is not running and the operator initiates a
diagnostic request sequence such as repeated
actuations of the pedal within a short period of time
following reset.
Limp Home Mode
The system is capable of "limp-home" mode in the
event of particular faults or failures in the system. In
limp-home mode the engine speed is approximately
1000 rpm at no load. A variety of fault conditions can
initiate limp-home mode. These fault conditions and
resulting actions are determined during calibration
and are OEM customer specific.
Service Tool
A scan tool/monitoring device is available to monitor
system operation and assist in diagnosis of system
faults This device monitors all sensor inputs, control
outputs, and diagnostic functions in sufficient detail
through a single access point to the SECM to allow
a qualified service technician to maintain the system.
This Mototune software (licensed by Mototron
Communication) is secure and requires a crypt-
token USB device to allow access to information.
LPG Fuel System Operation
The principles outlined below describe the operation
of MI-07 on an LPG fuel system.
An LPG fuel system consists of the following
components:
• Fuel filter
• Electric fuel lock-off solenoid valve
• Fuel pressure regulator/vaporizer
• Two orificed fuel trim valves
• Gas/Air mixer with fixed orifice for trim system and
fuel temperature sensor
• Miscellaneous customer-supplied hoses and
fittings
Fuel is stored in the customer-supplied LPG tank in
saturated liquid phase and enters the fuel system
from the tank as a liquid and at tank pressure. Fuel
passes through a high-pressure fuel filter and lock-
off solenoid, and is then vaporized and regulated
down to the appropriate pressure to supply the
mixer. The regulator controls the fuel pressure to the
gas/air mixer.
