Chery A15. Manual - part 249

 
2. Fuel supply system control logics 
- Logic of fuel pump startup        
The fuel pump will run for 0.5s after the ignition switch is turned on. The pump will stop if no 
valid 58X signals are detected; the engine starts running; the fuel pump starts running after ECM 
detects two valid 58X signals.  
- Logic of fuel pump shutoff 
The fuel pump will stop running after the turning speed signals have been lost for 0.8s.  
Start the pre-injection 
The pre-injection will only inject once during normal startup. The conditions for pre-injection 
startup are as follows:  
- The engine starts running (ECM detects at least 2 valid 58X signals) 
- Fuel pump relay is actuated 
- Fuel pump working time exceeds the delayed voltage accumulation period 
- No pre-injection before 
Once the above conditions are satisfied, the pre-injection will be carried out in all cylinders.  
 
 
3. Engine startup performance 
Engine startup performance refers to the engine startup performance at various ambient 
temperatures.  
 
 
 
 
 
 
 
 
 
 
 
 
 

Startup Temperature and Air-fuel Ratio 

 
 
 
 
 
 
 
 
 
 
 

 

 
4. Modifications of engine air mixtures 
When the engine is running at normal working temperature, its partial load control is closed-loop 
fuel control. At this moment, system will carry out real time modifications of the fuel injection 
quantity through the engine’s electronic control module on the basis of the feedback voltage 
signals from the oxygen sensor so that the air mixture composition may be as close to the 
theoretical air-fuel ratio as possible, the transfer rate of poisonous exhausts by the three-way 
catalyst may be optimized and the fuel costs may be saved.  
When the engine is running within the normal working temperature range, its full load control is 
open-loop fuel control. At this moment, the system will control the fuel injection quantity with 
relatively higher air-fuel ratio and increase the ignition advance angle appropriately with no 
engine knock created in order to optimize the power output. The system will also utilize the 
exhaust temperature mathematical model established during demarcation to control the exhaust 
temperature and protect the engine and the three-way catalyst.  
The system will judge the engine full load conditions by the signals from the throttle position 
sensor. The system will consider that the engine is working at full load when the throttle opens 
over 80% and 90% of the maximum.  
When the driver steps down the accelerator pedal for acceleration, the system will increase the 
fuel injection accordingly to ensure that the engine has sufficient fuel to power up. The increased 
fuel injection quantity is proportional to the variation ratio of the throttle opening.  
The system will firstly delay the ignition advance angle accordingly during acceleration and then 
gradually resume it in order to avoid the impact on the transmission system caused by the drastic 
torque increase during acceleration.  
When the engine power is approaching its full capacity during acceleration, the system will 
temporarily shut off the air-conditioning system to ensure sufficient engine power output for 
acceleration.  
Whatever condition it may be, the system will cut off the fuel supply if the engine speed has 
exceeded the maximum turning speed preset in the system to protect the engine and avoid 
runaway; when the engine speed slows down to within the maximum speed, the system will 
resume fuel supply.  
When the driver releases the accelerator pedal when the engine is running normally, the car will 
slide on and the engine will be running back. At this moment, the car needs no power from the 
engine; but the engine will produce increased poisonous exhausts due to insufficient combustion 
caused by closed throttle and low air intake. Therefore, the system will shut off fuel supply to 
substantially reduce the production of poisonous exhausts and save fuel.  
If the engine fails to start for a couple of times, there will be accumulated fuel that is not 
combusted in the cylinder. At this moment, the driver may fully step down the accelerator pedal 
to start the engine and the system will automatically apply very low air-fuel ratio to use up the 
extra fuel in the cylinder during engine running.  
 
 
 
 
 
 
 

 

 
5. Calculation of fuel injection pulse width 
 

 

Calculation of fuel injection（从空燃比开始顺时针翻译） 
Air-fuel ratio                closed-loop modification           Higher AFR during acceleration 
Lower AFR during deceleration 

Fuel supply cutoff during deceleration 

Exhaust cycle 

Voltage modification 

Fuel injection pulse width 

Spray nozzle constant 

Self-leaning modification 

Air-filling efficacy 

Air flow 

Air-filling temperature   

Manifold pressure 

 
- Air-fuel ratio (AFR) 
Startup AFR, normal startup AFR, AFR for cleaning extra fuel in the cylinder, AFR during 
engine running, AFR at engine-cooling status, AFR at engine-heating status, theoretical AFR, 
power higher AFR, catalyst overheating protection AFR, engine overheating protection AFR 
- Absolute pressure of air intake manifold 
The absolute pressure of the manifold is obtained by the MAP sensor on the air intake manifold.  
- Intake air temperature 
Intake air temperature refers to the temperature of air going into the engine cylinder; it is 
acquired by the water temperature and intake air temperature sensors.  
- Intake air efficiency 
Intake air efficiency is the ratio of the air flow actually entered the cylinder to the air flow as 
calculated based on equation of ideal status.  
- Self-learning 
Self-learning is used to correct the gradual changes arising from long-term engine running and 
any error of engine and its component.  
- Closed-loop feedback correction 
Closed-loop feedback correction refers to the control of actual AFR as close to the theoretical 
AFR as possible by the oxygen sensor.  
 

 

 
 
 
Closed-loop control 
 
 
Open-loop control 
Operation request 

System control   

Operation 

Control result 

Closed-loop control 
Operation request 

System control   

Operation 

Control result 

Error monitoring 
 
- Higher ARF during acceleration 
Higher ARF to avoid instantaneous diluted fuel for the engine and to improve motive power of 
the car when the system detects that TPS, MAP and IAC are substantially increased 
- Lower ARF during deceleration 
Lower ARF to avoid instantaneous thick fuel for the engine and to improve exhaust emission and 
driving performance when the system detects that the TPS, MAP and IAC are substantially 
decreased 
- Fuel supply cutoff during deceleration 
When the system detects that the engine and the car are decelerating, it will cut off the fuel 
supply to reduce exhaust emission and reduce oil consumption.  
- Protective fuel cutoff 
The system will stop fuel injection if any of the following conditions is satisfied:  
The fuel supply will be cut off when the engine turning speed is higher than 6,000rpm and 
resumed when it is lower than 6,000rpm.  
The fuel supply will be cut off when the system detects any ignition system fault 
The fuel supply will be cut off when the system voltage is higher than 22V and the engine 
turning speed is higher than 1,100rpm and resumed when the voltage is lower than 20V.