Bluebird T12 (1986-1991)

Pre-heating plugs (Nissan Bluebird T12)

Depending on the circuit used, it is possible to install spark plugs with different designs: without insulation from the engine ground and with insulation from the engine ground. When implementing the circuit discussed above, both types of spark plugs are used, and if all the spark plugs are connected in parallel, then only spark plugs without insulation from the engine ground are used. Check the spark plug without removing it using an ohmmeter: if spark plugs without insulation from the engine ground are installed, check for a circuit between the spark plug terminal and the housing; if spark plugs with insulation from the engine ground are installed, check for a circuit between the spark plug terminals. In both cases, the ohmmeter should show almost zero resistance, since the resistance of the spark plug working element is 0.235 ohms.

Before installing the spark plug, be sure to remove any carbon deposits from the cylinder head opening under the spark plug so as not to apply too much force to the spark plug when installing it. Install a new spark plug with a new silicone gasket. After installation, be sure to check the spark plug for proper operation using an ohmmeter. The spark plug control system can be checked using a voltmeter connected between the spark plug power bus and ground. Connect the voltmeter and turn on the ignition. The voltmeter should show the power source voltage for the first 10 seconds (the duration may be slightly different depending on the air temperature), then the voltage value should decrease by half and remain at this level for approximately 10 minutes (at a coolant temperature below 60°C) after the engine starts.