Polaris Virage TX 2000 Service Manual page 280

FFI™ FUEL INJECTION
Theory
Engine Management Module (EMM) continued.
• Alternator variable 38 to 45 Volts
• Barometric Pressure
The EMM, besides controlling engine operation, has a number of other important programmed functions. It:
• Stores Service Codes
• Activates S.L.O.W.™ (Speed Limiting Overheat Warning) System
• Provides cold start enrichment
• Controls the engine monitor gauge light
• Generates a tachometer signal
• Prevents excessive engine RPM
• Controls electric fuel pump operation
• Records engine operating hours
The EMM is an EEPROM design, so service codes will not be lost if the battery is disconnected. Service codes
that have been stored for 15 or more running hours, but have not reoccurred, will automatically be eliminated from
memory.
Internal EMM Sensors
Five sensors are located inside the EMM; barometric pressure, EMM temperature, alternator 38 to 45 volt sys
tem, battery 12 volts, and ROM verification. Since none are serviceable parts, failure correction would require
replacement of the EMM.
Barometric Pressure (BP) Sensor: The BP sensor is a silicon pressure sensor having a diaphragm sealed air
passage that generates an AC voltage signal. It senses ambient air pressure through a screened port that's open
to atmosphere. The BP signal enables the EMM to compensate for pressure changes caused by altitude so it
can adjust fuel flow accordingly. If sensed values are out of limits, or the sensor or circuit fails, the EMM will turn
on the MFI "check engine" light, and store a service code.
EMM Temperature Sensor: Monitors fuel injector driver circuit temperature to prevent it from exceeding design
limits. One or more fuel injectors could malfunction should this occur. If sensor values are out of limits, or the
sensor or circuit fails, the EMM will turn on the MFI "check engine" light, and store a service code. The EMM will
also initiate S.L.O.W.™, only if excessive temperature is the failure mode.
45 Volt Circuit Sensor: Monitors rectifier/regulator 38 to 45 volt output. This is the circuit that powers the fuel
injectors. If voltage exceeds the expected range, the EMM will initiate S.L.O.W. ™, store a service code, and turn
on the MFI "check engine" light. Voltage below the expected range will store a service code and turn on the MFI
"check engine" light, but will not put the engine into S.L.O.W.™
RPM limiter: This feature of the EMM programming prevents engine damage due to excessive RPM. Normal
engine operation automatically returns as soon as engine RPM drops down to the specified range.
ROM Verification: A continual EMM self-test of factory programming. The EMM will turn on the "check engine"
light and store a service code if, at any time, a program failure is detected.
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