Section 05 2–TEC ENGINE MANAGEMENT
Subsection 01 (OVERVIEW)
This engine management system controls the fuel
injection, the ignition timing and the electronically
controlled RAVE.
As shown in the SDI CONTROL SYSTEM illustra-
tion, the ECM is the central point of the fuel injec-
tion system. It reads the inputs, makes computa-
tions, uses pre-determined parameters and sends
the proper signals to the outputs for proper engine
management.
The ECM also stores the fault codes and general
information such as: operating conditions, vehicle
hours, serial numbers, customer and maintenance
information.
ELECTRONIC FUEL INJECTION
The ECM receives the signals from different sen-
sors which indicate engine operating conditions at
milli-second intervals.
Signals from sensors are used by the ECM to de-
termine the injection parameters (fuel maps) re-
quired for optimum air-fuel ratio.
The CPS and TPS are the primary sensors used
to control the injection and ignition timing. Other
sensors are used for secondary input.
IGNITION TIMING
The ECM is programmed with data (it contains ig-
nition mappings) for optimum ignition timing un-
der all operating conditions. Using engine operat-
ing conditions provided by the sensors, the ECM
controls the ignition timing for optimum engine op-
eration.
ELECTRONICALLY CONTROLLED
RAVE
The electronically controlled RAVE (e-RAVE) offers
two performance enhancements to conventional
RAVE system.
– The opening of the valve is now activated elec-
tronically. A solenoid holds the valve closed.
The ECM monitors altitude, engine tempera-
ture, throttle position and RPM, and operates
the solenoid in optimal conditions.
– The valve is now opened by crankcase pres-
sure, as opposed to exhaust pressure. The
greater and more constant pressure from the
crankcase opens the valve more crisply.
NOTE: An electric heating element has been
added to the RAVE solenoid to ensure proper
function in very cold weather.
KNOCK SENSOR
A knock sensor is mounted on top of the cylinder
head. It detects specific vibration that would be
typically generated by engine detonation. If deto-
nation occurs, the knock sensor detects it and the
ECMs retards the ignition advance and extend the
injection period temporarily (it goes in a specific
mode) until detonation stops.
ENGINE MODES OF OPERATION
The ECM controls different operation modes of
the engine to allow proper operation for all possi-
ble conditions: Cranking, start up, idle, warm up,
normal operation, engine speed limiter, flooded
engine and limp home (see below).
FLOODED ENGINE (DROWNED
MODE)
If the engine does not start and it is fuel-flooded,
this special mode can be activated to prevent fuel
injection and ignition while cranking. Proceed as
follows:
With tether cord cap on its post while engine
is stopped, press completely and HOLD throttle
lever.
Press the START/RER button. The mode is now
on.
The engine should be cranked for 20 seconds.
NOTE: No spark occurs on drowned mode.
Release START/RER button and throttle lever. Try
to start the engine normally.
If the engine does not start, it may be necessary
to remove the spark plugs and crank the engine
with rags over spark plug holes. Refer to COM-
PONENT INSPECTION AND ADJUSTMENT.
MONITORING SYSTEM
The ECM monitors the electronic components of
the fuel injection system and some components
of the electrical system.
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