Chery SQR 7160 sedan. Manual — part 126

load and accelerating/decelerating operating conditions, and carry out fuel injection volume

control corresponding with throttle opening. Throttle position sensor includes a

potentiometer, and the moving parts is operated by throttle shaft. During operation, ECU

supply 5V voltage to sensor and measured parameter is variable of throttle opening from

minimum to maximum.

Operation Operational theory of throttle position sensor is shown as fig 7.

(3) TMAP sensor (air intake temperature, pressure sensor)

★ TMAP sensor combined air intake temperature sensor and air intake pressure
sensor .

Air intake pressure sensor is an important sensor, which utilize pressure-resistance effect
of semi-conductor element, transferring pressure change in intake manifold to voltage
change.

Air intake temperature sensor is used to measure air intake temperature, which is a
negative temperature coefficient (NTC) resistance thermo-sensitive element.And the
resistance decrease with temperature increasing.

(4) Crankshaft speed and position sensor

This system adopts electromagnetic crankshaft speed and position sensor with inner
composition of watered magnet round cylinder and coil. Crankshaft speed and position
sensor are fixed on transmission housing, corresponding with sensor signal gear tooth.
Sensor signal gear has 60-2 teeth. When 1-4 cylinder is in Top Dead Center position，the
sensor is at the 20

th

tooth counting from signal gear absent tooth; and when 2-3 cylinder is

in Top Dead Center position，the sensor is at the 50

th

tooth counting from signal gear absent

tooth.

Fig 7. Crankshaft speed and position sensor Operation Theory

1. Crankshaft speed and position sensor 2. Signal gear 3. Corresponding signal with 2nd absent tooth 4. Signal

Besides identification of Top Dead Center position，signal can be used by ECU for:

-Managing of ignition (ignition advance angle and charging duration)；

-generating rotaional speed signal；

-Confirming synchronization of each engine revolution by identifying the two absent
teeth.

Under the condition of other factors not changing, the peak value of sensor output
voltage is determined on the distance between crankshaft rational speed and position
sensor and gear tooth. The clearance between the head of crankshaft rotational speed and
position sensor and the top of signal gear tooth is 1±0.5mm.

(6) Oxygen sensor

Oxygen sensor is used for detecting the content of oxygen in exhaust, which is a major
component for ensuring actual air/fuel ratio of engine to approaching theoretical air/fuel
ratio.

Oxygen sensor is mounted on the exhaust front pipe, before 3-way catalyst converter.
Oxygen sensor mainly consists of a ceramics shell made of zirconium oxidize，on which the
internal/external surface of closed side is coated with platinum, with a protect tube out the
ceramics and a metal housing out the ceramics for protecting. The external surface of
zirconium oxidize is exposed to exhaust gas and internal surface is exposed to atmosphere.

Oxygen sensor operation theory: when temperature is over 300℃，zirconia can separate

ox ion from of oxygen in the exhaust gas passing through oxygen sensor. If contents of

oxygen in two sides of oxygen sensor are different, a potential difference between two sides

will generate. Measuring the potential difference will obtain the difference of oxygen

contents between two environments (gas air side and exhaust gas side), and then the

information will be sent to ECU. Due to different voltage is corresponding to different

air/fuel ratio, ECU can control fuel injection of injector to regulate gas air/fuel mixture,

making air/fuel mixture approach theoretical value to realize closed loop control. Under

fuel cutting-off and engine full load condition, oxygen sensor does not operate, which is

called open loop.

Voltage

Rich

Lean

excessive air coefficient

Fig 9 Oxygen Sensor and Performance Character Chart

ceramics body 2. Protecting tube 3.outer metal shell of sensor 4. heating resistor

a. signal positive(+) , exposed to air b. signal negative(-) exposed to exhaust gas

The oxygen sensor is heated oxygen sensor, which can enter operating mode much

early. Under normal operating condition, oxygen sensor voltage periodically varies within

0.1～0.9V.

Note: Because lead has inhibitory action to platinum oxidation and leaded gasoline

will make oxygen sensor lose function quickly and deteriorate exhaust gas. Therefore

leaded gasoline is absolutely forbidden.

(7) 3-way catalyst converter

3 way catalyst converter is installed on exhaust, before muffler and can decrease 3

kinds of pollutants’ content in exhaust gas simultaneously: carbon monoxide (CO),

unburned hydrocarbon (HC) and oxide (NOX). When the air/fuel ration of engine is

approaching to theoretical air/fuel ratio, the catalyst efficiency of 3-way catalyst converter

reaches the maximum. When harmful gas under 300℃～800℃ pass through the center of 3

way catalyst converter, it will be catalyzed by precious metal on the ceramic element, taking

oxidizing and reducing reaction, and converts to harmless gas.

4. Ignition system

Ignition system is a grouped electronic control ignition system (1—4 cylinders in one

group, 2—3 cylinders in the other group). The ignition system is integrated with fuel

injection system, which is an electronic system with a built-in power supply module, and

canprovide with all kinds of optimal ignition value Upon input instaneous physical

parameters related with engine operating condition, all kinds of optimal ignition values can

be wrote into program via a managing circuit.

ECU controls 2 primary coils on and off. Secondary coil will generate a high voltage

due to secondary induction when primary coil current is suddenly cut off, and 1-4 cylinder

and 2-3 cylinder spark plugs connected to secondary coil final terminal via ignition wire

will obtain high voltage and therefore firing is achieved.

Basic ignition advance angle is regulated and determined upon engine coolant

temperature and air temperature. Under most conditions, ECU dynamically compensate

basic ignition advance angle upon engine rotational speed and air intake manifold absolute

pressure to obtain optimum ignition advance angle. Under a very low engine idle speed

condition, ignition advance angle keep constant.

(2) Static state high voltage output ignition coil

Fig 10 Ignition Coil Schematic

1. Cylinder-1 ignition terminal 2. cylinder-2 ignition terminal 3. cylinder-3

ignition terminal

The system uses a closed magnetic circuit coil packed in a plastic container with a coat

of epoxy outside, which has special ability of non-electric conduct, mechanicalness, thermal

characteristic and high temperature resistance. The part of primary coil near iron core

lessens the flow of magnetic current causing secondary coupling can reach maximum and

has the following capabilities:

- High ignition voltage storage;

-High energy transmission performance of secondary coil;

-Long ignition duration;

- Rapid secondary voltage increasing

(3) Knock sensor

High temperature, mechanical parts aging and wearing, low octane gasoline etc may be

possible knock causes. Since knock may damage engine, to prevent continuous knock,,