Checking the elements of the ignition system
The ignition coil
The efficiency of the ignition coil can be checked as follows.
■ Remove the end of the lead wire from the ignition coil from the distributor cap.
■ Remove the manifold cap.
■ Rolling the car with the gear engaged, cause the circuit breaker contacts to close.
■ Turn on the ignition and bring the removed end of the wire closer to ground, at a distance of approx 10 mm.
■ Open the contacts several times. This should cause a spark to jump between the cable end and ground. If there is no spark, the ignition coil is damaged.
Ignition cable
The insulation of the ignition cable must not be cracked. Malfunctions in the operation of the ignition system may be caused by the resistance of the ignition cable, which instead of a bundle of wires has a graphite-nylon fiber. This type of cable has a low mechanical resistance to bending and breaking. This disadvantage is not present in the braided copper wire. However, its use requires the anti-interference resistor sockets to be fitted to the spark plugs.
Spark plugs
To unscrew the candles, remove the caps. If the engine is very dirty, first you need to loosen the candles, blow out their surroundings with compressed air, and then unscrew it completely.
The appearance of the spark plug tip is indicative of the combustion process taking place in the engine:
normal – color insulator from gray-yellow to brown, likewise the ground electrode; lighter sediment will occur after driving at high speed; clean the tip of the candle, check and, if necessary, adjust the electrode gap,
with carbon deposit - black, dry carbon deposit indicates improper combustion; caused: too rich air-fuel mixture, insufficient air supply, boot device not shutting down, spark plug gap is too large, for the high heat value of the candle; another cause of carbon build-up may be: drop in ignition voltage due to coil failure, improper distance between breaker contacts or damaged ignition cable; carbon deposits on only one spark plug may be caused by the sticking of the cylinder valve, while carbon deposit on all candles is a sign of frequent use of the car in city traffic or a wrong selection of candles;
oil – black, greasy residue from charred oil indicates improper combustion process; possible reasons for it: high engine wear, damaged piston rings or valve guides; if the insertion of candles with a higher temperature does not bring improvement, and the ignition system is operational, then the compression pressure must be measured;
overheated - white droplets of molten material on the insulator cone and pitting in the electrodes may be caused by wrong ignition setting, too lean mixture, gasoline with a high lead content, insufficient cooling, Leaking spark plug or insufficiently closing valves; it is recommended to check the ignition and cooling system settings first; you can test candles with an increased thermal value. The gap between the electrodes of the candles should be equal 0,7 mm. This interval can be increased to 0,8 mm. The measurement is made with a feeler gauge. while adjusting by bending the ground electrode with a suitable tool. To check, that the insulator cone is not chipped. The least damaged spark plugs should be replaced. The thread of the candle is cleaned with a wire brush, when checking the condition of the gasket, the gasket should be smooth, clean surface and a thickness equal to at least half the thickness of the new gasket. The spark plug must not be screwed in without or with two seals. The spark plug tightening torque is 40 Nm.