Isuzu 2000 Trooper UX, Руководство по ремонту

Страница: 1440 / 2150

6E–571
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Run Mode
The run mode has the following two conditions:
D
Open loop
D
Closed loop
When the engine is first started the system is in “open
loop” operation. In “open loop,” the PCM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAF sensors.
The system remains in “open loop” until the following
conditions are met:
D
The HO2S has a varying voltage output showing that
it is hot enough to operate properly (this depends on
temperature).
D
The ECT has reached a specified temperature.
D
A specific amount of time has elapsed since starting
the engine.
D
Engine speed has been greater than a specified RPM
since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters “closed loop” operation. In
“closed loop,” the PCM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.
Starting Mode
When the ignition is first turned “ON,” the PCM energizes
the fuel pump relay for two seconds to allow the fuel pump
to build up pressure. The PCM then checks the engine
coolant temperature (ECT) sensor and the throttle
position (TP) sensor to determine the proper air/fuel ratio
for starting.
The PCM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors are
energized by pulsing the injectors for very short times.
Throttle Body Unit
The throttle body has a throttle plate to control the amount
of air delivered to the engine. The TP sensor are also
mounted on the throttle body. Vacuum ports located
behind the throttle plate provide the vacuum signals
needed by various components.
Engine coolant is directed through a coolant cavity in the
throttle body to warm the throttle valve and to prevent
icing.
025RY00005
General Description (Electronic
Ignition System)
Camshaft Position (CMP) Sensor
CMP is located Left Rear cylinder head. When the
Hall-effect switch is activated, it grounds the signal line to
the PCM, pulling the camshaft position sensor signal
circuit’s applied voltage low. This is a CMP signal. The
CMP signals is created as piston #1 is approximately 25
°
after top dead counter on the power stroke. If the correct
CMP signal is not received by the PCM, DTC P0341 will
be set.
0014
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position. Refer to
Electronic Ignition
System section for additional information.