CAC Gasoline Engine Maintenance And Servicing Manual
106
5.malfaction, cause and correction
Malfuction cause Correction
Fuel pump. fuel
injector IVM523
check for operation by CHECK—UP1
Tachometer
senser.
Check wring, sensor resistance and installation of the sensor.
Dual relays Check for function, connector connection and blown fuse.
Vehicle cannot start
35——pin
connection
Check for the wiring connection to ECU.
Difficult to start;
idling speed too
high or too low
speed control
solenoid.
check for solenoid operation and 4—pin connection by
CHECK—UP1.
warning light on
During idling,
λsensor
Check for the wiring, proper sensor tightening torque and the
sensor heater’s operation
warning light on for
a long time
Diagnosis
warning light
Check for the signal wiring grounding.
warning light
doesn’t turn on
Diagnosis
warning light
The bulb is broken or circuit is open
Rough idling at high
temperature.
Throttle valve
sensor or water
temperature
sensor
the throttle valve opening angle and water temperature signal
displayed by CHECK—UP1 should match the engine operation.
Rough idling at low
temperature.
coolant
temperature
sensor or intake
air temperature
sensor
The temperature indicated should be in the vicinity of the
ambient temperature.
Idle intermittent
wave
1—throttle
valve body
30MM4
1.check the throttle valve cable for proper adjustment, smooth
movement.
2.if the throttle valve cable is correctly adjusted and may move
smoothly, remove it. Check the throttle valve for resistance by
turning it with a hand (for friction);
3.display the throttle valve position by CHECK—UP1. If both 1
and 2 are correct and engine speed is still high , while
CHECK—UP1 displays “angle is greater than the allowable
angle”, then the malfunction is positively determined. It is
necessary to replace the throttle valve potentiometer. If the angle
is within the specified range, sensor wiring and connector should
be checked.
Idling speed
fluctuates
continuously at high
temperature.
1.throttle valve
body
1.2 seal
1.3 vacuum
connection
1. check the above item 1,2,3 for intermittent idling speed
functions;
1.2 check the seal between cylinder head and throttle valve body;
1.3check the vacuum lines to the two vacuum passages,
which are of absolute pressure. check the fuel vapor
recirculation passages, which are connected to the throttle
valve body and intake manifold.
Check the vacuum tube sealing in intake manifold for brake
servo .
Vehicle performance
deteriorates
1—fuel supply
system
1. Check for fuel supply. If fuel pressure is 1±0.1bar, it is ok;
2. If malfunction still remains after upper throttle body
(30mm12) is replaced, with a pressure regulator in the upper
throttle body, check fuel filter and fuel pipes.
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