Safety measures when working with elements of the electronic ignition system
The voltage in the high-voltage part of the ignition system is up to 30 kV. Under adverse circumstances, such as high humidity in the engine compartment, power surges can break through the insulation, which, if touched, can lead to electrical injury. To avoid injury and / or damage to the electronic ignition system, when working on vehicles with electronic ignition, you must adhere to the following rules:
- before turning the crankshaft with the starter (e.g. when checking compression) turn off the ignition and disconnect the connector from the power amplifier located on the ignition coil;
- do not touch with your hands and do not disconnect the high-voltage wires of the ignition system while the engine is running or when the engine is turning the crankshaft with a starter;
- disconnect the wires of the ignition system only when the ignition is off;
- connect and disconnect control devices (tachometer and ignition tester) only when the ignition is off;
- when towing a car that has a malfunction in the ignition system or is suspected of having one, disconnect the wire from the power amplifier;
- it is allowed to start the engine for 1 minute using a quick charger with a maximum voltage of 16.5 V. After each start attempt, a pause of at least 1 minute should be made;
- the ignition coil cannot be replaced with a coil from another model or modification of a car with a different engine. In no case should an ignition coil be installed from a contact ignition system;
- a complete disconnection of the battery can only be carried out with the ignition off, otherwise the ignition system control unit may be damaged;
- wash the engine only with the ignition off;
- persons with pacemakers should not work with the electronic ignition system;
- after heating to a temperature of more than +80°С (e.g. for painting) do not start the engine immediately after heating;
- when working with electric and spot welding, completely disconnect the battery;
- do not apply voltage to the control unit to simulate the output signal.
Elements of the ignition system
Location in the engine compartment of the elements of the ignition system of engines with two camshafts in the cylinder head (DOHC): 1 - high voltage wires; 2 - spark plugs; 3 - ignition coil
Location in the engine compartment of the elements of the ignition system of engines with one camshaft in the cylinder head (SOHC): 1 - ignition coil; 2 - high voltage wires
Location in the engine compartment of the elements of the ignition system of engines with two camshafts in the cylinder head (DOHC) shown in figure 7.28. Location in the engine compartment of the elements of the ignition system of engines with one camshaft in the cylinder head (SOHC) shown in the figure.
Ignition coil
Removal and installation
Remove the ignition fuse (fusible link).
Disconnect the wires.
Fastening of the ignition coil of engines with a working volume of 1.1 l
Fastening of the ignition coil of engines with a working volume of 1.3, 1.5 and 1.6 l
Remove the ignition coil by unscrewing the mounting bolt.
Install in the reverse order of removal.
Checking the technical condition
Checking the resistance of the primary winding of the ignition coil: 1 - the ignition coil of the second and third cylinders; 2 - ignition coil of the first and fourth cylinders
Check the resistance of the primary winding of the coils between the contacts «1» And «2».
Check the resistance of the secondary winding of the coils between the high voltage outputs of the coil of the first and fourth cylinders and the high voltage outputs of the second and third cylinders.
Checking the resistance of the secondary winding of the ignition coil
Rated resistance of the secondary winding of the ignition coils (13±15) kOhm
Attention! Check the resistance of the secondary windings only with the connector of the ignition coils disconnected.
Spark plug
Automotive manufacturers recommend the use of a certain type of spark plug, but other types of spark plugs with the appropriate glow rating can also be used.
Spark plugs should be cleaned with a sandblaster every 10,000 km. In this case, the appropriate interelectrode distance should be set. When adjusting the distance, never bend the center electrode, as its ceramic insulator may burst.
Before unscrewing the spark plugs, check that there are no foreign objects in the spark plug wells in the cylinder head. Washers, bolts or small stones that have fallen into the holes of the candles will destroy the valves, valve seats or cylinder head at the first start of the engine. The spark plug consists of a central electrode, an insulator with a housing and a side electrode «masses». The central electrode is hermetically installed in the insulator. The latter is firmly connected to the body. An ignition spark jumps between the central and side electrodes, igniting the air-fuel mixture in the engine cylinder. Starting qualities of the engine, the nature of its idling, acceleration and maximum speed of the car depend on the spark plug. Therefore, it is not recommended to switch from candles recommended by the manufacturer to candles of a different type without special reasons. Thermal characteristic (glow number) spark plug is an indicator of the degree of heat load of the spark plug in the engine under certain operating conditions. Candles are selected in such a way that under all possible operating conditions of the car they reach the self-cleaning temperature. The lower the glow number of a spark plug, the higher its resistance to glow ignition and the lower its resistance to fouling. The higher the glow number, the lower the resistance of the plug to glow ignition and the higher its resistance to fouling.
The heat number is contained in the designation of the candle.
Withdrawal
The tip of the high-voltage wire of the ignition system of engines with one camshaft in the cylinder head (SOHC)
The tip of the high-voltage wire of the ignition system of engines with two camshafts in the cylinder head (DOHC)
Disconnect wires from spark plugs.
Note. To avoid damage to the high voltage wire, disconnect it by pulling on the end of the wire, not on the wire itself.
Use a spark plug wrench to remove all spark plugs from the cylinder head.
Attention! Make sure that no dirt gets into the cylinders through the sockets for the spark plugs.
Checking the technical condition
Places to visually check the condition of the spark plug
Check the spark plugs for the following defects:
- insulator damage (point 1 in the figure);
- electrode burnout (point 2);
- soot (point 3);
- gasket damage (point 4);
- damage to the porcelain insulator at the end of the candle (point 5).
Gap (A) between spark plug electrodes
Check with a feeler gauge and, if necessary, adjust the gap A between the electrodes of the spark plugs.
Nominal value of the gap between the electrodes of the spark plug (when using unleaded gasoline) 1.0–1.1 mm.
Screw in the spark plugs by hand and tighten to 20–30 Nm.
Overtightening the spark plugs can damage the threads of the spark plug sockets.
Determining the condition of the engine by the appearance of spark plugs
The condition of the engine can be assessed by the color of carbon deposits on the electrodes of the spark plugs.
Checking spark plugs (when turning the crankshaft of the engine)
Scheme for checking the spark plug when turning the crankshaft of the engine with a starter (ignition on): 1 - ignition coil; 2 - spark plug; 3 - ignition switch; 4 - electronic control unit
Scheme for checking the spark plug when turning the crankshaft of the engine with a starter (ignition on) shown in the figure.
Connect the wire to the spark plug. Connect the outer electrode of the spark plug (frame) With «weight» and turn the crankshaft. Due to the low ambient pressure, only short sparks are produced. However, if the spark plug is good, sparking should occur in the spark gap of the spark plug (between electrodes). With a faulty spark plug, there will be no sparking due to current leakage through the insulator.