Table of contents: Coal deposits ↓ Oiling ↓ Overheat ↓ Too early ignition ↓ Conductive gloss ↓ Short circuit of electrodes ↓ Normal condition of the candle ↓ Ash formation ↓ Wear ↓ Detonation ↓ Splashing ↓ Mechanical damage ↓
Spark Plug and Ignition Coil Installation Components
1 - Ignition coil; 2 - Spark plug
Caution! Spark plugs should only be replaced when the engine is cold or slightly warm. Removing the spark plugs when the engine is hot can damage the threads in the cylinder head.
1. Switch off the ignition and remove the air intake sleeve together with the air cleaner housing (see Chapter Fuel and exhaust systems).
2. Disconnect the ignition coil wiring connector, remove the mounting bolt and remove the coil from the spark plug.
3. Remove the spark plug using a long 16mm socket wrench, being careful not to tilt it.
4. Assess the condition of the spark plugs (see illustrations below). If necessary, correct any possible faults that can be judged by the condition of the spark plugs. Carbon deposits on the electrodes can be removed with compressed air under pressure 588 kPa for 20 sec., do not use a wire brush for this purpose. Checking and adjusting the interelectrode gap between spark plug replacements is not required.
5. Under normal conditions, standard spark plugs should be installed. "Hot" spark plugs should be installed if standard spark plugs become fouled under conditions such as frequent engine starts and low air temperatures. "Cold" spark plugs should be installed if standard spark plugs cause detonation under conditions such as prolonged high speed driving and frequent high engine speed operation.
6. Install new spark plugs and tighten them securely 19.6÷29.4 Nm.
7. Further installation is carried out in the reverse order. Tighten the ignition coil mounting bolts with force 3.8÷4.4 Nm.
Coal deposits
Symptoms: The presence of soot indicates an over-enriched fuel-air mixture or weak spark intensity. It causes misfires, makes starting difficult and leads to instability of engine operation.
Data posted on the website (NISSANBOOK.ru)
Recommendations: Check if the air cleaner is clogged, the fuel level in the float chamber is too high, the choke is stuck and the contacts are too worn. Try using spark plugs with a longer insulator, which increases resistance to contamination.
Oiling
Symptoms: Oiling of the spark plug is caused by wear of the oil-deflecting caps. Oil gets into the combustion chamber through worn valve guides or piston rings. It causes misfires, makes starting difficult and leads to instability of engine operation.
Recommendations: Perform mechanical repairs and replace spark plugs.
Overheat
Symptoms: Porous, white insulator, erosion of electrodes and absence of any deposits. Leads to a reduction in spark plug life.
Recommendations: Check if it meets the requirements Specifications the glow plug rating, whether the ignition timing is set correctly, whether the fuel-air mixture is too lean, whether there are any vacuum leaks in the intake manifold and whether the valves are jammed. Also check the coolant level and whether the radiator is clogged.
Too early ignition
Symptoms: The electrodes are melted. The insulator is white, but may also be contaminated due to misfires or foreign particles entering the combustion chambers. May cause engine failure.
Recommendations: Check the glow number of the installed spark plugs, the ignition timing, and the quality of the mixture (isn't it too poor?), whether the cooling system is clogged and whether the lubrication system is functioning normally.
Conductive gloss
Symptoms: The insulator has a yellowish color and a polished appearance. Indicates a sudden increase in temperature in the combustion chambers during sharp acceleration. Normal deposits melt, acquiring the appearance of a varnish coating. Leads to misfires at high speeds.
Recommendations: Change the spark plugs (cooler, while maintaining the same driving style).
Short circuit of electrodes
Symptoms: Combustion waste gets into the interelectrode space. Solid deposits accumulate, forming a bridge between the electrodes. Leads to ignition failure in the cylinder.
Recommendations: Remove deposits from the interelectrode space.
Normal condition of the candle
Symptoms: Gray-brown color and slight wear of the electrodes. The glow number of the spark plugs corresponds to the type of engine and its general condition.
Recommendations: When replacing spark plugs, install spark plugs of the same type.
Ash formation
Symptoms: Soft, brownish deposits on one or both spark plug electrodes. They are caused by oil and/or fuel additives. Excessive buildup can insulate the electrodes and cause misfires and rough running under acceleration.
Recommendations: If deposits accumulate quickly, replace the oil seals to prevent oil from entering the combustion chambers. Try changing the fuel brand.
Wear
Symptoms: Rounding of the electrodes with a small accumulation of deposits at the working end. The color is normal. It leads to difficulty in starting the engine in cold, wet weather and increased fuel consumption.
Recommendations: Replace the spark plugs with new ones of the same type.
Detonation
Symptoms: Insulators may be chipped or cracked. Inaccurate spark plug gap adjustment techniques may also damage the insulator. Piston damage may result.
Splashing
Symptoms: After a long period of misfire, deposits may become loose while the combustion chamber remains at operating temperature. At high speeds, deposits flake off the piston and stick to the hot insulator, causing misfires.
Recommendations: Replace the spark plugs or clean and reinstall the old ones.
Mechanical damage
Symptoms: Can be caused by foreign materials entering the combustion chamber or occur when the piston hits a spark plug that is too long. Leads to cylinder failure and piston damage.
Recommendations: Remove foreign particles from the engine and/or replace the spark plugs.