If the normal operation of the engine is disturbed, first check the condition of the electrical wiring and connectors. Check the condition of the air filter element and the condition and gap of the spark plugs. Check the serviceability of the crankcase ventilation hoses and the adjustment of the accelerator cable. If the engine still continues to run erratically, check the compression in the engine cylinders.
Check the operation of the fuel injector, clean it if necessary.
If the engine is still erratic, check the ignition system components.
If the problem persists, check the integrity of the fuses and the condition of the electrical connectors and wiring. The electrical connectors must be free of melted contacts, moisture, dirt, corrosion and other damage.
After conducting an independent check, contact a specialized station for diagnosing the fuel injection system on special equipment.
The location of the elements of the ignition and fuel injection systems of a six-cylinder engine is shown in Figure 4.1–1, for an eight-cylinder engine - in fig. 4.1–2.
Pic. 4.1–1. Location of elements of ignition and fuel injection systems in the engine compartment of vehicles with six-cylinder engines: 1 - switch N122; A - 3-pin dark brown connector, for primary circuits of ignition coils; B - brown 4-pin connector from the control unit; 2 - engine control unit J192; 3 - electrical connectors: A - black, 2 - pin from the lambda sensor heater; B - 1-pin from the lambda sensor; C - 3-pin brown, from the switch; D - 2-pin blue, from the knock sensor; E - 3-pin white, for powering the ignition coils; 4 - diagnostic socket; 5 - throttle potentiometer with switch G69; 6 - electrical connectors: A - 2-pin black, for the lambda sensor heater; B - 1-pin, from the lambda sensor; C - 2-pin blue, from the knock sensor; D - 3-contact gray, from the speed sensor; E - 3-pin black, from the ignition timing sensor; 7 - coolant temperature sensor G62; 8 - Hall sensor G40; 9 - speed sensor G28; 10 - sensor for setting the ignition timing G4; 11 - knock sensor G66; 12 - ignition coils; 13 - nozzles; 14 - wire connection with «weight»; 15 - air flow meter G70; 16 - solenoid valve of the 1st adsorber N80; 17 - knock sensor G61; 18 - fuel pressure regulator; 19 - lambda sensor G39; 20 - fuel pump relay J17; 21 - idle speed stabilization valve N71; 22 - wire connection with «weight»; 23 - intake manifold switching valve N156; 24 - lambda sensor G108
Pic. 4.1–1. Location of elements of ignition and fuel injection systems in the engine compartment of vehicles with six-cylinder engines: 1 - switch N122; A - 3-pin dark brown connector, for primary circuits of ignition coils; B - brown 4-pin connector from the control unit; 2 - engine control unit J192; 3 - electrical connectors: A - black, 2 - pin from the lambda sensor heater; B - 1-pin from the lambda sensor; C - 3-pin brown, from the switch; D - 2-pin blue, from the knock sensor; E - 3-pin white, for powering the ignition coils; 4 - diagnostic socket; 5 - throttle potentiometer with switch G69; 6 - electrical connectors: A - 2-pin black, for the lambda sensor heater; B - 1-pin, from the lambda sensor; C - 2-pin blue, from the knock sensor; D - 3-contact gray, from the speed sensor; E - 3-pin black, from the ignition timing sensor; 7 - coolant temperature sensor G62; 8 - Hall sensor G40; 9 - speed sensor G28; 10 - sensor for setting the ignition timing G4; 11 - knock sensor G66; 12 - ignition coils; 13 - nozzles; 14 - wire connection with «weight»; 15 - air flow meter G70; 16 - solenoid valve of the 1st adsorber N80; 17 - knock sensor G61; 18 - fuel pressure regulator; 19 - lambda sensor G39; 20 - fuel pump relay J17; 21 - idle speed stabilization valve N71; 22 - wire connection with «weight»; 23 - intake manifold switching valve N156; 24 - lambda sensor G108
Pic. 4.1–2. Location of elements of ignition and fuel injection systems in the engine compartment of vehicles with eight-cylinder engines: 1 – ignition coil switch N122, N192; 2 - engine control unit J220; 3 - fastening element of the relay and fuses; relay power supply system Motronic J271; immobilizer relay J341; 4 - electrical connectors for the G39 lambda sensor and the Z19 lambda sensor heater; 5 - lambda sensor G39 with heater Z19; 6 - coolant temperature sensor G62; 7 - temperature sensor of the air entering the engine G42, 8 - throttle valve potentiometer G69, combined with the idle switch F60; 9 – the valve of stabilization of frequency of rotation of idling N71; 10 - engine speed sensor G28; 11 - electrical connector of the lambda sensor G108 and heater Z28; 12 – an electric socket of the gauge of frequency of rotation of the engine G28; 13 - lambda sensor G108 with heater Z28; 14 - Hall sensor G40; 15 - knock sensor G66; 16 - ignition coils of cylinders 5–8, respectively N164, N189, N190, N191; 17 - fuel injectors of cylinders 5-8 respectively N83, N84, N85, N86; 18 - air control valve nozzles N212 (installed only on vehicles with engine code AKG/ AKJ/ AKH (MVEG III) and OBDII; 19 - intake manifold switching valve N156; 20 - knock sensor G61; 21 - nozzles of cylinders 1–4, respectively N30, N31, N32, N33; 22 - ignition coils of cylinders 1-4, respectively N, N128, N158, N163; 23 - solenoid valve of the 1st adsorber N80; 24 - air flow meter G70 in the upper section of the air filter housing
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