The task of spark plugs is to ignite the fuel-air mixture in the combustion chamber. This creates temperatures of up to 2500°C and combustion pressures of up to 60 bar. In order for sparks to jump off the ends of the plugs reliably, the "remnant" of the central electrode is surrounded by a ceramic insulator. The central electrode, together with the connecting bolts, is also inserted into a conductive glass mass, which firmly fixes them to the body of the plugs and seals them in front of the combustion chamber. As soon as the required ignition voltage and the optimal parametric ignition angle are reached, they are discharged in the form of discharges from the central electrode to the side electrodes. The discharges have such energy as to ignite the fresh fuel mixture in the combustion chamber.
Powerful sparks: spark plugs with several side electrodes. Not every spark plug is suitable for the Mondeo. However, spark plugs from famous manufacturers are equivalent to the "original" ones. The figure shows a multi-electrode spark plug with a surface-air spark discharge with four side electrodes and a heat-conducting copper central electrode.
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1 - Connecting contact,
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5 - Side electrodes,
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Variable value - heat number
In order for spark plugs to work reliably, they must quickly reach their self-cleaning temperature (approximately 400°C) immediately after starting the engine. If it is not reached, combustion residues settle on the insulator cone relatively quickly. At full load, the temperature at the ends of the spark plugs should not exceed 800°C if possible. Otherwise, just like the next stop at a gas station, defects will appear in the engine (burnt pistons, piston scoring, etc.).
Naturally, the operating conditions for spark plugs in all engines are different. Only the heat rating determines whether the spark plugs and the power unit are compatible. If, for example, you use spark plugs with a low heat rating, the thermal cone of the insulator will heat up significantly. This can lead to uncontrolled glow ignition, which can even lead to engine destruction. On the contrary, if spark plugs with a high heat rating were selected, they will not reach their required self-cleaning temperature – the insulator cone will become dirty and over time, igniting sparks may not be visible.
Increases automatically – the distance between the electrodes
In addition to the correct censer number (see table), the spark plugs must also have the appropriate distances between the electrodes. In new spark plugs, this is, for example, 1.3 millimeters, but over time it increases: high flashover voltage leads to regular removal of metal particles from the electrodes. Larger distances between the electrodes also require higher ignition voltage. Consequence: ignition failure, the engine may not start.
Therefore, when replacing spark plugs, be sure to check that the plugs have the correct sintering number, electrode spacing and threads specified for your Mondeo.
Genuine Spark Plugs for Mondeo
Engine |
Spark plug specifications |
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Duratec-HE 1.8/2.0-liter (81, 92, 107 kW) |
Motorcraft AGSF 22PPJ |
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Duratec-VE (125, 151 kW) |
Motorcraft AWSF 32F |
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DuraTorg-DI (66, 85 kW) |
Motorcraft EZD 38* |
| *Glow plugs. | |