This section only briefly describes the injection system malfunctions caused by failure of certain sensors. The procedure for removing and installing units of the fuel and engine control systems is given in the subsections "Power supply system" and "Engine management system".
The feedback injection system includes a catalytic converter of exhaust gases and an oxygen concentration sensor in the exhaust gases (on the Ford Fusion, two converters and four oxygen concentration sensors are installed in parallel to each other), which provides feedback. The sensors monitor the oxygen concentration in the exhaust gases, and the electronic control unit, using their signals, maintains such an air-fuel ratio at which the converters operate most effectively. Moreover, the main control sensors are the sensors installed on the catalytic collector, and the sensors installed at the output of the converters are diagnostic, they determine the quality of the entire engine management system as a whole. If the engine control unit, based on the information from the diagnostic sensors, detects an excess of oxygen concentration in the exhaust gases that cannot be eliminated by calibrating the system using the signals from the control sensors and indicates some kind of system malfunction, it will turn on the engine management system malfunction indicator lamp in the instrument cluster and enter the error code into memory for subsequent diagnostics.
Caution: Before removing any fuel injection system components, disconnect the negative battery cable.
Attention! Disconnect the battery only when the ignition is off.
Caution: Do not start the engine if the battery cable terminals are not tightly tightened.
Caution! Never disconnect the battery from the vehicle's electrical system while the engine is running.
Caution! When charging, disconnect the battery from the vehicle's electrical system, as increased current during charging may damage electronic components.
Attention! Do not allow the electronic control unit (ECU) to heat up above 65°C in working condition and above 80°C in non-working condition (e.g. in a drying chamber). The ECU must be removed from the vehicle if this temperature is exceeded.
Caution! Do not disconnect or connect the wiring harness connectors to the ECU when the ignition is on.
Caution! Before performing arc welding on a vehicle, disconnect the wires from the battery and the wire connectors from the ECU.
Attention! Perform all voltage measurements using a digital voltmeter with an internal resistance of at least 10 MOhm.
Warning! The electronic components used in the injection system are designed for very low voltage, so they can easily be damaged by electrostatic discharge. To prevent damage to the ECU by electrostatic discharge:
- do not touch the ECU connectors or electronic components on its boards with your hands;
- when working with the programmable read-only memory (PROM) of the control unit, do not touch the terminals of the microcircuit.
Attention! It is not allowed to operate an engine with a neutralizer on leaded gasoline - this will lead to rapid failure of the neutralizer and oxygen concentration sensor.
Caution: When working in rainy weather, do not allow water to come into contact with the electronic components of the fuel injection system.
Check the injection system in the following order.
1. Check the ground connection of the engine and battery.
2. Check the fuel pump and its fuel filter.
3. Check the fuses and relays for switching on the injection system elements.
4. Check the reliability of the contacts in the pads with wires of the injection system elements.
5. Check the injection system sensors.
The vast majority of fuel injection system faults are caused by failure of the following sensors:
- crankshaft position sensor - complete failure of the injection system, the engine does not start;
- throttle position sensor (installed in the throttle cover) - loss of power, jerks and dips during acceleration, unstable operation in idle mode;
- coolant temperature sensor - difficulty starting in cold weather, as you have to warm up the engine, maintaining the speed with the accelerator pedal, when overheating, the power is significantly reduced, detonation appears;
- inlet air temperature and absolute pressure (vacuum) sensor in the intake manifold - if the temperature measurement function fails, fuel consumption increases, exhaust gas toxicity increases, and if the flow measurement function fails, fuel consumption increases, dynamics significantly deteriorates, engine starting problems occur;
Note: The engine shown has two solenoids, one each for the intake and exhaust camshafts.
- knock sensor - the engine is very sensitive to the quality of gasoline, increased tendency to detonation;
- oxygen concentration sensor in the exhaust gases (lambda probe) - increased fuel consumption, decreased engine power, unstable idling. Possible damage to the catalytic converter of the exhaust gases;
- phase sensor - power loss, increased fuel consumption.
(Information for this article was taken from the website: fordbook)