High temperature resistant spark plugs

The purpose of the spark plugs is to ignite the air-fuel mixture in the combustion chamber. This results in temperatures up to 2500°C and combustion pressures up to 60 bar. In order for sparks to confidently jump off the ends of the candles, «remainder» The central electrode is surrounded by a ceramic insulator. The central electrode, together with the connecting bolts, is also inserted into the conductive glass mass, which firmly fixes them with the candle body 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 enough energy to ignite the fresh fuel mixture in the combustion chamber.

Powerful sparks: spark plugs with multiple side electrodes. Not every spark plug is suitable for a Mondeo. Still, candles from famous manufacturers are equivalent «original». The figure shows a multi-electrode surface-air spark plug with four side electrodes and a heat-conducting copper center electrode.

1 - Connecting contact, 2 - Ceramic insulator, 3 - candle body, 4 - O-ring,	5 - Side electrodes, 6 - Thermal cone of the insulator, 7 - Central electrode.

Variable value - glow number

In order for spark plugs to work reliably, they must quickly reach their self-cleaning temperature immediately after starting the engine (about 400°C). If it is not reached, then relatively short-term combustion residues settle on the cone of the insulator. At full load, the temperature at the ends of the spark plugs should, if possible, not exceed 800°C. Otherwise, that's for sure, like the next stop at a gas station, defects will appear in the engine (burnt pistons, piston scuffing and so on).

Naturally, the working conditions for spark plugs in all engines are different. Only the glow number determines whether the candles and the power unit are consistent with each other. If, for example, you use candles with a low glow number, then the thermal cone of the insulator becomes very hot. This can lead to uncontrolled pre-ignition, which can even lead to destruction of the engine. On the contrary, if candles with a high glow number were chosen, then they do not reach their required self-cleaning temperature - the insulator cone becomes dirty and, over time, igniting sparks may not be seen.

Increases automatically – distance between electrodes

In addition to the correct censer number (see table) candles must also have appropriate distances between the electrodes. In new plugs, for example, it is 1.3 millimeters, but it increases with time: the high voltage of the overlap leads to the regular removal of metal particles from the electrodes. Large distances between the electrodes require a higher ignition voltage. Consequence: Ignition failure, engine may not start.

Therefore, when replacing spark plugs, always make sure that the spark plugs have the prescribed burn rate for your Mondeo, the correct electrode spacing, and the correct threads.

Original spark plugs for Mondeo

Engine	Specification of spark plugs
Duratec-HE 1.8/2.0 liter (81, 92, 107 kW)	Motorcraft AGSF 22PPJ
Duratec-VE (125, 151 kW)	Motorcraft AWSF 32F
DuraTorg-DI (66.85 kW)	Motorcraft EZD 38*
* Glow plugs.