If the ignition coil


Delphi Technologies specialists give recommendations in case of malfunction in the ignition system.

The purpose of the car’s ignition system is to ensure the appearance of an electrical spark to ignite the fuel-air mixture in the engine cylinders at the right moment. One of the key components of the system is the ignition coil.

The ignition coil is essentially a transformer that converts a low battery voltage (usually only 12 V) into high-voltage, necessary in order to break through the integlective spark plug, ignite the fuel and start the engine.

The design and work of the coil in several words can be described like this. The coil consists of a primary chain, in which several hundred turns of the winding, and a secondary chain, in which there are already thousands of turns of the winding and there is a steel core.

The electric current of the primary circuit creates a magnetic field around the core, which causes the current leap in the secondary chain, increasing the voltage until it becomes enough to create a spark. Ignition occurs.

The ignition voltage may vary in the range from 5000 to 25,000 B and depends on many factors. This is the magnitude of the interelectrode gap, the spark plug resistance, the ratio of air and fuel in the mixture, the temperature of the ignition candle, the load on the engine and others. Some systems require a peak load to 40,000 V. Such power is determined by the ratio of secondary and primary windings (usually about 80: 1). The higher this ratio, the higher the potential voltage.

There are a number of major reasons why the ignition coils may fail:


• Increased interelectrine clearance due to wear of spark plug electrodes

• Vibration

• overheating and resistance to the coil

• Excessive humidity


• Engine failry lamp lights up

• Fuel consumption increases

• Natural accumulations in the car exhaust system are noticeable.

• Engine launch is difficult or engine spontaneously stalls

• ignition pass appear

If there is a suspicion of the coil malfunction, then there is a certain algorithm for identifying this fault. It is useful to know:

• First, experts read the fault codes with a diagnostic scanner. The values of the defective coil codes are compared with the codes normally functioning.

• Check the coil on the presence of mechanical damage — cracks in the case, damage to the wiring or connectors.

• Measure the interelectrine clearance in the ignition candle, as well as the resistance of the high-voltage wire (if available).

• When the ignition is on, the coil supply voltage is measured. Voltage should be more than 10.5 V.

• Check the primary and secondary winding of the coil using a multimeter. The primary resistance of most coils should be in the range from 0.4 to 2 ohms, and the secondary — from 5,000 to 20 000 Ohm. If any value does not match the specification, the coil is replaced. The zero value indicates the presence of a short circuit in the coil, and the high value is to break into the coil.

After the malfunction is confirmed, the coil is replaced:

• When the ignition is turned off, the electrical connector is disconnected, the fastening bolts are developed and removed the coil from the place of attachment.

• Dielectric lubricant is applied to the base of the candle tips (this will provide protection against breakdown). Install a new coil (while the bolts are tightened with the recommended point) and connect the connector.

• The diagnostic device delete all fault codes and turn off the engine malfunction control lamp. Run the engine to check.

And let’s go …

Based on Delphi TECHNOLOGIES