Clean the spark plug recesses in the cylinder head with compressed air.
Unscrew the spark plugs with a spark plug wrench. By the appearance of the candle, conclusions can be drawn about the operating modes of the engine. In this case, the following rules should be followed:
Electrodes and insulator
- neutral gray color - normal operation of the candle and the correct composition of the mixture;
- black - supersaturated mixture;
- light gray - lean mixture,
- oiled - spark plug failure or poor fit of piston rings (check compression).
Check for leakage in the insulator If traces of leakage currents are found on the surface of the insulator, check if the spark plug connector is cracked and replace the spark plug if necessary.
Checking electrical connections
Check up firmness of connection of all wires to the coil of ignition and to the distributor of ignition. Replace damaged contacts.
Check the ignition wires for cracks. Replace ignition wires if necessary.