Distributed fuel injection

Overview

Distributed fuel injection (MFI) consists of sensors that evaluate the status of the engine, an electronic engine control unit (PCM), which in turn controls the entire system on the basis of information received from sensors and actuators, actuation which occurs upon commands from PCM . PCM controls the supply of fuel to the engine cylinders, air flow at all engine idling and ignition timing. Furthermore, PCM has several modes of self-diagnosis, which facilitates troubleshooting when they occur.

Fuel control

The pulse injector control and ignition timing are selected in such a way as to ensure optimum air-fuel ratio of the mixture in the constantly changing conditions of the engine. The inlet port of each cylinder has a single nozzle. Fuel is supplied to the fuel pump under pressure in the fuel manifold. To maintain the required pressure in the system has a pressure regulator. Fuel is supplied under pressure to the nozzles. Such a fuel supply system is called distributed. Typically, the fuel injector is injected once during two revolutions of the crankshaft. Electronic engine control unit enriches the mixture in the operating mode "open loop" in that when the engine is cold and operated at a high load. If the engine is warm and running at normal load, PCM, when you turn on "feedback" through the oxygen sensor heater creates a stoichiometric composition of the mixture, which ensures best engine performance in terms of the "purity" of the exhaust gas using the three-way catalytic converter.

Idle control motor

Idle speed are maintained at an optimum level by controlling the amount of air passing through the bypass passage in accordance with changes in the flow conditions and idling engine load. PCM controls the actuator (stepping motor), a regulator of idling (ISC), maintaining the idle speed to a predetermined level, determined by the temperature of the coolant in the engine and the load on the air conditioner. Furthermore, when the air conditioner is switched off and the idling stepper motor controller adjusts the flow area since the bypass channel to prevent the fluctuation of the idle speed of the engine in case of accidental load change.

Management of the ignition timing

Power transistor ignition system installed in the primary circuit of the system is switched on and off to change the current in the primary circuit of the ignition coil. This provides change control ignition timing and maintains its optimal value when changing the operating mode of the engine. The ignition timing of the PCM varies depending on the engine speed, the air filling the cylinders, the coolant temperature and the atmospheric (barometric) pressure.

The fuel pump control

The inclusion of the fuel pump relay so that current is supplied to the pump when scrolling through the engine starter and its normal operation.

Management of the electromagnetic clutch of the air conditioning compressor

On and off an electromagnetic compressor clutch.

Fan relay control

Cooling fans and air conditioning condenser fan are changed in accordance with a change in coolant temperature and the vehicle speed.

Mode diagnostics

When a fault occurs in any sensor or actuator associated with the system of decrease in toxicity, illuminates the MIL engine (?�CHECK ENGINE?�), that informs the driver of the fault.

When a fault occurs in any sensor or actuator, the fault appears appropriate diagnostic code.

These random access memory (?�RAM?�) electronic engine control unit with sensors and actuators can be read by diagnosing device. Finally, the actuators may be powered and monitored independently of the system.

Instructions for checking the fuses

Remove the fuse and measure the resistance between the loaded side of the fuse and the "weight". Set the switches of all circuits which are connected to this fuse in the "on" position. If the resistance substantially equal to 0 ohms, this means a short-circuit between the switch and the load. If this resistance is different from 0 ohm, it means there is no short-circuit at the moment, but a one-time shorting circuit that is blown fuse.

The main reasons for short circuit as follows:

- The destruction of the posting of the car body;

- Damage wiring insulation due to its deterioration or heat;

- Penetration of water into the connector or the circuit;

- The human factor (incorrect connections chain).

Checking the fuel injection system

If the components (sensors, the engine control unit injector, etc.) of fuel injection (MFI) is defective, the result will be stopped or the fuel supply will fail in exact feeding fuel under different engine operating modes. You may experience the following situations:

- The engine does not start or starts with difficulty;

- Unstable work of the engine idling;

- Poor manageability engine.

When the above symptoms, first necessary to diagnose the vehicle.

Diagnostic operation by car

Memory DTCs: After the RSM for the first time detected a failure, the diagnostic code is recorded, and when you restart the engine fault reappears. (Fault in the car test cycle). However, in the case of the fuel system (rich / lean mixture, misfiring), the DTC will appear only at the first fault detection.

Erase DTCs: After storing the diagnostic code, and if the PCM again detects the fault in the next 40 driving cycles, the diagnostic code is erased from the memory of the PCM. However, in the case of the fuel system (rich / lean mixture, misfiring), the diagnostic code is cleared if the following two conditions:

When driving conditions (engine speed, coolant temperature, etc.) Are identical to those for which this fault has been detected for the first time.

When RSM again detects the fault in the next 80 driving cycles.

The MIL engine (MIL)

When the lights warning lamp Engine (MIL), this means there is a malfunction in the car.

However, if you do not take any repair actions, MIL will turn off automatically after 3 consecutive driving cycles.

After ignition MIL comes on and stays on for about 5 seconds to show that the lamp is working.

Turning MIL may indicate a fault in the following elements:

- The catalytic converter;

- fuel system;

- Air flow sensor (MAF);

- Temperature sensor in the intake manifold (IAT);

- The coolant temperature sensor (ECT);

- Throttle position sensor (TPS);

- The front oxygen sensor;

- Rear oxygen sensor heater;

- Rear oxygen sensor;

- The front oxygen sensor heater;

- Injector;

- Misfiring;

- The crankshaft position sensor (CKP);

- The camshaft position sensor (CMP);

- The fuel vapor recovery system;

- Vehicle speed sensor (VSS);

- A regulator of idling (ISC);

- Electronic engine control unit (PCM);

- The gauge of absolute (barometric) pressure in the intake manifold (MAP) (except for vehicles with 2.7 liter V6);

- The gauge-switch is fully closed throttle;

- Exhaust gas recirculation (except vehicles with engine 2.7 liter V6).

Calibration

Switch on the ignition (ignition key position ?�ON?�) and verify that the MIL engine caught fire about 5 seconds and then goes off.

If the warning light does not light, check the wiring for continuity, the fuse and the lamp itself in the absence of burnout.

Self-diagnosis

Electronic engine control unit monitors the input / output signals (some permanently, others - only under certain conditions). If the engine-ECU has detected a fault (permanent or temporary disruption in the system), it will write the corresponding fault code in memory, and will send a signal to the standard diagnostic connector. The diagnostic results (DTCs) can be read via the MIL or engine tester HI-SCAN (Pro). Fault codes are stored in the memory of the electronic engine control unit only if the power supply from the battery. Fault codes may be erased or pi disconnecting battery terminal connector or the engine control unit, or by using a tester HI-SCAN (Pro).

The verification procedure (self-test)

Methods of testing (using the diagnostic tool such as GST)

Switch off the ignition.

Connect the scan tool to the Data Link Connector (diagnostic socket).

Turn on the ignition.

Using the scan tool read the fault codes.

Make the necessary repairs in accordance with the recommendations of the diagnostic card.

Erase the diagnosis codes.

Disconnect the scan tool.