Chery SQR 7160 sedan. Manual — part 127

advanced identification and correction strategy such as enrich air/fuel mixture shall be

adapted to reduce ignition advance angle.

Operational theory: Knock sensor consist of piezoelectric non-resonant quartz and

converts electric signal into mechanical energy in form vibrations. The sensor is

connected to engine ECU through a shielded wire. When knock occurs, ECU will receive

peak values of high-energy signal, which is discriminable from normal combustion signal.

During knocking, air/fuel mixture shall accordingly enrich to ensure exhaust temperature is

within the safe specification when appropriate reducing of ignition advance angle is needed,

The knock sensor is installed on the cylinder body between cylinder2 and cylinder3,

on the side of intake manifold. Tighten torque is 19.6±4.9Nm. USE SPECIAL CARE to

this torque specification.

5. Preventing fuel from evaporating and fuel vapor recycle system

By this system, fuel vapor formed in fuel tank and fuel feed system is combusted in engine

combustion chamber after filtering, prevent fuel vapor from being exhausted into

atmosphere.

(1) Active carbon canister

Active carbon canister is used for absorbing and storing fuel vapor in fuel tank and fuel

vapor is then transferred into air intake manifold through carbon canister control solenoid.

(2) Carbon canister solenoid

Under the control of ECU, carbon canister

solenoid has the following functions:

1. When ngine stop running and under stop

condition, carbon canister solenoid prevent

fuel vapor in fuel tank from entering air intake

manifold. When ignition key is turned to MAR

position, closed carbon canister solenoid will

start to work. l start to work.

2. At the stage of engine start-up, carbon canister

keep closed to prevent fuel vapor over enriching

air/fuel mixture, which will last till engine

Fig 11 Konck Sensor

1. Knock sensor connector 2. Knock sensor 3. Sensor wiring 4. locking nut

coolant temperature reaches specified value (about 65℃). When engine warming up, ECU

will send a square wave signal to carbon canister. Carbon canister on and off is regulated

by cycle ratio of signal itself. Therefore ECU may control fuel vapor quantity input to

intake manifold, preventing mixture richness making an abrupt change.

When throttle is at idle position, engine speed less than 1500 rpm, intake manifold pressure

lower than a preset value and air/fuel mixture richness self-adapt, carbon canister solenoid

keep closed to ensure an more optimum engine performance.

(3) Fuel tank ventilation safety valve

it has the following functionsThe valve is installed on filter cover and has following

functions upon pressure inside fuel tank:

1. When pressure inside fuel tank exceeds 0.1—0.18bar, fuel vapor will be given out from

outlet (safety function).

2. When 0.020—0.030bar vacuum is generated in the fuel tank, air is drawn in

(ventilation function)

6. Engine anti-theft system (optional)The engine anti-theft unit is an alien frequency radar

anti-theft unit.

Fig 13 Engine anti-theft unit schematic

1. Anti-theft ECU (ignition key) 2. Engine ECU 3.Anti-theft unit ECU

The alien frequencies radar anti-theft system is an electric device, connecting with engine

control system, prevent vehicle from disoperation. One of characteristics engine

anti-theft unit on and off need no additional operation by user. When use alien frequency

radar transponder, the function is on as the key turns off and the function is off as the key

turns on. Each time the key turn on, the engine ECU needs a special authentication code.

The authentication code is processed upon code stored in ignition switch circuit. Only this

condition meets can the engine start.

Alien frequency radar anti-theft unit mainly consists of 3 components: anti-theft ECU,

antenna and transponder.

Anti-theft unit ECU is in a black plastic box and usually located on instruments panel.

Its electric device is in-line with alien frequency radar transponder and connects with engine

ECU. Antenna is fixed in a special channel in ignition switch and consists of copper coil

wrapped by a plastic jacket and a connector, which can connect with anti-theft ECU. The

structure of anti-theft ECU is as shown in fig 14.