Honda 2004 Odyssey, Service Manual

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PGM-FI System
A/C Compressor Clutch Relay
A/C Switch
Alternator Control
Barometric Pressure (BARO) Sensor
Camshaft Position (CMP) (Top Dead Center (TDC))
Sensor
Crankshaft Position (CKP) Sensor
Engine Coolant Temperature (ECT) Sensor
Ignition Timing Control
Injector Timing and Duration
11-45
CMP (TDC) SENSOR A
CMP (TDC) SENSOR B
CKP SENSOR
THERMISTOR
The Programmed Fuel Injection (PGM-FI) system is a
sequential multiport fuel injection system.
When the PCM receives a demand for cooling from the
A/C system, it delays compressor engagement, and
enriches the mixture to assure smooth transition to the
A/C mode.
The A/C (air conditioning) switch signals the PCM
whenever there is a demand for cooling.
The alternator signals the PCM during charging. The
PCM then controls the voltage generated by the
alternator according to the electrical load determined
by the Electrical Load Detector (ELD) and driving mode.
This reduces engine load to improve fuel economy.
The BARO sensor is inside the PCM. It converts
atmospheric pressure into a voltage signal that
modifies the basic duration of the fuel injection
discharge.
The CMP (TDC) A/B sensor input is used by the PCM to
determine ignition timing at start up (cranking) and
when crank angle is abnormal.
The CKP sensor input is used by the PCM determine
timing for fuel injection of each cylinder and to detect
engine speed.
The ECT sensor is a temperature dependent resistor
(thermistor). The resistance of the thermistor decreases
as the engine coolant temperature increases.
The PCM contains the memory for basic ignition timing
at various engine speeds and manifold absolute
pressure. It also adjusts the timing according to engine
coolant temperature.
The PCM contains the memory for basic discharge
duration at various engine speeds and manifold
pressures. The basic discharge duration, after being
read out from the memory, is further modified by
signals sent from various sensors to obtain the final
discharge duration.
By monitoring Long Term Fuel Trim, the PCM detects
long term malfunctions in the fuel system, and sets a
diagnostic trouble code (DTC).
(cont’d)
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