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.