Chery Amulet Engine. Manual — part 17

2.2 Lower body (air system)—description and function of accessories
Excepted that connecting throttle valve to accelerator pedal by a lever, the following parts should be

installed on the lower body.

·throttle valve position sensor
·stepper motor
·hot water loop near the throttle valve and idle air by-pass
·absolute pressure signal port in the lower throttle valve (necessary to be connected with pressure

sensor)

·PCV recirculation pipe

——Throttle valve position sensor “PF2C”.
Figure 140 shows the position sensor case structure, also the relationship between output characteristic,

output signal and throttle valve opening ange.

·Sensor component is consisted of a potentiometer. The slipping ruler of potentiometer is driven directly

by accelerator pedal which is proportional with throttle valve opening.

·the potentiometer is inserted into plastic case with two baffles on the bracket. There are two holes in the

bracket for installing the potentiometer on throttle valve.

· there is spline on the shaft. The spine provides data about throttle position. The data is used to confirm

idle operation condition (accelerator pedal released), full load (accelerator pedal depressed) and accelerating or

Fig.139 temperature sensor and principle

water

Air

Connecting chart

Fig. 140 throttle valve position sensor and operation chart

Ground

Signal output

Power

Throttle valve opening (angle)

decelerating conditions.

· with absolute pressure sensor out of work, the position sensor will function when working condition

comes back.

·ECU supplies 5V voltage to the variable resistance terminal of throttle valve potentiometer . And

potentiometer output voltage varies with throttle valve position.

·sensor needs not adjustment(through assembling hole), for ECU program may self adjust to minimum

impedance (2°to 14°).

Warning——the following order should be taken during potentiometer replacement:
1. Tighten mounting bolt on the new potentiometer.
2. Turn ignition key to the MAR before connecting line to the potentiometer, and wait for several

minutes.

3. Turn ignition key to stop.
4. Connect wire to the potentiometer’s insert hole.
5. Insert CHECK-UP1 tester. Turn ignition key to CN and erase trouble display.
6. Keep connection until throttle valve position displayed on the screen is 2°～14°. If the parameter

is above 14°, you should check throttle cable and make sure it’s correct (not very tight). Or it needs
to be adjusted again.

Notice: Don’t adjust the potentiometer bolt if it does not return to the specified value of throttle valve

opening angle. The potentiometer should be replaced because it fails.

——Engine idle speed actuator (idle control stepper motor)
Idle control stepper motor is a position actuator of high precision and high distinguishability ( +/-50r/min)

for controlling idle speed.

It is consisted of stepper motor and screw rod-type reduction gear. The reduction gear converts the valve

rotating into linear movement. Stepper motor receives the signal from ECU and makes valve shaft move by
screw rod changing air by-pass passage (see figure 8). Then engine air intake will change during idling. It will
vary with coolant water temperature whether air intake is increasing or decreasing, which keeps speed stable.
Engine minimum idle air intake is set by adjusting throttle valve opening when by-pass channel is closed
completely. Be sure not to touch mixture adjustment bolt. Engine maximum idle air intake is set by valve
returning position, i.e. about 200 steps (8mm travel). The operation steps are the function of engine conditions
(preheating cycle, electrical load, A/C working condition, engine running (hot)).

Timing：

Rotate the engine pulley (2) to keep cylinder 1 and cylinder 4 at TDC, i.e. the mark on the pulley (2) and
the mark (3 and 4) on the timing wheel cover of engine must be matched (see figure. 145).

Speed/ TDC sensor

Check if the sensor is located in the twentieth tooth after the breach in the flywheel signal panel
1— Speed/ TDC sensor (crankshaft position sensor)
2— Pulley
3— TDC reference point on the pulley
4— TDC reference point on the timing gear cover
5— synchronous tooth
Check the air gap between the sensor and flywheel：

Magnetic thickness gauge is used for checking the air gap between the sensor and flywheel. Measurement

should be made at least at three different teeth with a equal interval of 120°. The value should be 2±0.6mm.

A. Speed sensor signal
B.ECU power signal
C. Current circle for primary coil circuit

a. Ignition advance angle relative to cylinder 1
TDC

4.3 absolute pressure sensor
The sensing element of absolute pressure sensor is printed
in a ceramic membrane by the wheatstone bridge silk PCB.
One side of the membrane is absolute reference vacuum and
the other side is actual vacuum of the intake manifold. The
signal (piezoresistance type) produced by the distortion of
ceramic membrane which is installed in the bracket is
magnified by the circuit located in the carrier before being
transferred to ECU.

See from the front end, rotation direction

Top dead center position

Crankshaft
position sensor

Fig. 145 sensor position and timing
reference point

Fig. 146 Magnetic sensor output signal wave

3-way connector (figure. 147)
a. Supply 5V voltage
b. Negative pole signal
c. Positive pole signal

When engine is shut down, the sensitive membrane will bent
according to the value of atmospheric pressure (mmHg). After the

ignition switch is switched on, the actual atmospheric pressure may be obtained by this method.

When engine is running, the vacuum will produce a mechanical effect on the ceramic membrane of the

sensor resulting in the change of resistance.

For ECU supplies a absolutely constant 5V voltage, the
change of output voltage caused by the change of resistance is
indicated in figure. 148.

Sensor supplies the most important data to ECU for

calculating the intake air volume. When the pressure signal is P
＜97mmHg or P＞783mm Hg，if the throttle valve position
sensor doesn’t fail, the operation comeback will be performed
according to the throttle valve angle and speed value stored in the
calibration scale. If throttle valve fails, only one comeback value
may be applied—— about 442mmHg.

Note: If absolute pressure sensor needed to be

replaced, the connecting pipe must have the same
diameter and length as the original pipe.

5. Ignition advance calculation and high voltage distribution
The system uses two high tension ignition coils and assigns ignition voltages directly to spark plugs by
static electricity (distributorless ignition) directly. Connector and controlling triode are comprised in the ECU
injection system and connected to ECU connector 1 and connector 19 . (figure. 149).

Fig. 147 absolute pressure sensor

Fig.148 sensor output