Chery A11. Manual - part 117

        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,, 

 

 

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