In the fuel injection system of the VAZ-21126 engine with feedback, a catalytic converter and two oxygen concentration sensors are installed in the exhaust system, which provide feedback. The sensors monitor the oxygen content in the exhaust gases, and the electronic control unit, according to their signals, maintains such an air-to-fuel ratio at which the converter works most efficiently.
Attention! Before removing any components of the injection control system, disconnect the wire from the terminal «minus» battery.
Attention! Disconnect the battery only when the ignition is off.
Attention! Do not start the engine if the cable lugs on the battery are loose.
Attention! Never disconnect the battery from the vehicle's electrical system while the engine is running.
Attention! When charging, disconnect the battery from the car's on-board network.
Attention! Do not allow the electronic control unit to heat up (ECU) above 65°C in working condition and above 80°C in non-working condition (e.g. in a drying chamber after painting). If this temperature is exceeded, the ECU must be removed from the vehicle.
Attention! Do not disconnect or connect the wiring harness connectors to the ECU while the ignition is on.
Attention! 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 with a digital voltmeter with an internal resistance of at least 10 MΩ.
Attention! 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 ECU damage from electrostatic discharge:
- do not touch the computer plugs or electronic components on its boards with your hands;
- when working with programmable read-only memory (PROM) control unit, do not touch the microcircuit pins.
Attention! When working in rainy weather, do not allow water to enter the electronic components of the fuel injection system.
Check the injection system in the following order.
1. Check the connection with «weight» engine and battery.
2. Check pressure regulator, fuel filter and fuel pump.
3. Check the fuses and relays for switching on the elements of the injection system.
4. Check up reliability of contacts of pads with wires of elements of system of injection.
5. Check the sensors of the injection system.
The vast majority of fuel injection system malfunctions are caused by the failure of the following sensors:
- crankshaft position - complete failure of the injection system, the engine does not start;
- camshaft position (phase sensor) – transition to synchronous operation of injectors, deterioration in performance (dynamics, fuel consumption);
– mass air flow - an increase in fuel consumption, a significant deterioration in dynamics, jerks and dips, problems with starting the engine;
- throttle position - loss of power, jerks and dips during acceleration, unstable idling;
– coolant temperature — Difficulties with starting in the cold. You have to warm up the engine, maintaining the speed with the accelerator pedal. When overheating, power is significantly reduced, detonation appears;
– oxygen concentration (Lambda probe) – increased fuel consumption, reduced engine power, unstable idling (only on vehicles equipped with a catalytic converter). Possible damage to the catalytic converter of exhaust gases;
– detonation - the engine is very sensitive to the quality of gasoline, increased tendency to detonation;
– vehicle speed - possible deterioration of the dynamic qualities of the car in modes using maximum power (intense acceleration);
- rough road - deterioration of engine performance on rough roads.