Chery SQR 7160 sedan. Manual - part 41

CAC Gasoline Engine Maintenance And Servicing Manual

The following accessories and engine air filter are installed on the upper body of throttle valve.
·fuel system pipe and fuel return pipe
·fuel pressure regulator
·bottom-supplying fuel injector IWM
·intake air temperature sensor.

——Fuel pressure regulator
As engine is running, fuel pump supplies fuel (fuel supply volume of pump is about 80L/h) through

filter and pipe to fuel pressure regulator(chart 137). The regulator is designed to keep the specified fuel
pressure at 1bar(0.9-1bar), and redundant fuel will recirculate flowing into fuel tank. Fuel will clean and cool
injector during recirculation.

——working procedure of Fuel pressure regulator .

Spring (2) applies pressure on the diaphragm(7) connected

to sealing valve(6) keeping cavum closed between fuel
delivery pipe and fuel return pipe(4).

whe fuel pressure in pipe(3) exceeds 1 bar , pressure on

diaphragm(7) will overcome spring(2) resistance, then
diaphragm goes up raising sealing valve up to allow redundant
fuel to flow back and returns to proper work pressure.

during producing, fuel pressure regulator pressure is

calibrated by socket head bolt and will never changed under
any circumstance.

——Fuel

injector
1.  socket head regulator screw
2.  spring
3.  fuel output pipe
4.  fuel return pipe

5.  spring
6.  sealing valve
7.  diaphragm

Fig.137 fuel pressure regulator

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CAC Gasoline Engine Maintenance And Servicing Manual

IWM523 fuel injector applied in the system is of the shortened type of the first generation. It is entirely

made of stainless steel and superior in the function. The advantage may be embodied when the commercial
fuel containing corrosive material is applied. figure 138 shows fuel injector structure and some technical
parameters.

Technical parameters:

－winding resistance
R=1.8Ω+/-10%(20℃)
－power supply voltage
V=6-16V
－spraying shape
angle 30～90°
－operating temperature
-30～+110℃.

when fuel injector is not operating, it is sealed and doesn’t allow fuel drain. Fuel needed by engine, is

controlled by ECU(supplied electricity by relay (87))directly. And ECU decides the open time of each intake
order and fuel injection duration.

Fuel injection time is controlled by the following measures:
-synchronous(for normal operation) .injector opening corresponds with every TDC.
-not synchronous (for idling, cut-off, low speed, start operation).injector opening is completely

controlled by time and not related to TDC signal.

ECU has a basic current control circuit to control fuel injector. The circuit produces the maximal

current(signal) at the first control order speed up the opening of injector. Once maximum current is attained ,
the circuit will automatically change to and keep the current I=1A±0.3 A(Mean).

Injection duration is showed on the 2-dimension figure as a function of engine speed and intake manifold

absolute pressure . After engine warming up or speed turns to be stable, injection duration is 1～4mS.

Injection duration is increasing basically under special operation condition, such as accelerating, cold

starting, engine warming up. As accelerator pedal is released, fuel will be cut off.( ti=0mS). Running condition
and readjusting condition may be changed according to water/ intake air temperature or A/C condition.

——intake air temperature sensor “ATS05”
It is consisted of N.T.C.(Negative Temperature Coefficient) thermo resistance and 2-way junction box that

are installed in the plastic setting molding case. Sensor resistance will changed with intake air temperature.

Fig. 138 fuel injector

+12V relay

ECU 18 insert pin

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CAC Gasoline Engine Maintenance And Servicing Manual

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

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)

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CAC Gasoline Engine Maintenance And Servicing Manual

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
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  is  the  function  of  engine
conditions(preheating cycle, electrical load, A/C working condition, engine running (hot)).

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