Originally posted by TourDeForce:
If the plug wire or coil is going bad, it causes a mis-fire. The ECU then kicks up the voltage to the suspect cylinder to try & force spark through the plug & avoid damage to the engine. As the voltage spikes, this raises heat within the plug causing the core to expand & burst the insulator.

So, you can have good plugs in the engine, but if the wires or coil create too much resistance, the ECU still must raise the voltage to get adequate spark to that plug and poof, the plugs burst from the excess heat that is generated from an over-voltage condition.

JimR



Let me try to clear this up. The ignition coil is designed to have a specific maximum voltage. As ignition systems have improved over the years this maximum voltage has increased from 25,000 volts to something in the neighborhood of 60,000 volts. This maximum voltage is referred to as the AVAILABLE voltage.

The ignition system usually doesn't operate at AVAILABLE voltage. It operates at the REQUIRED voltage. The REQUIRED voltage is what is required to get the spark to jump across the gap. There are several things that will alter REQUIRED voltage, but chief among them is cylinder pressure. Some others are fuel mixture and spark plug condition. As the cylinder pressure rises creating more horsepower, the voltage required to fire the plug rises.

The difference between the AVAILABLE voltage and REQUIRED voltage is the RESERVE voltage.

When the REQUIRED voltage rises above the AVAILABLE voltage, or when there is no more RESERVE voltage, there will be a misfire.

One of the main reasons that spark plugs last as long as they do today is because the AVAILABLE voltage is so high that it will fire a plug that is worn so bad that it would have created a miss in engines of just a few years ago. Platinum tips also help in that they do not wear as fast.

So the idea that a processor of some sort increases the voltage to the plugs is hog wash.

Jim Johnson 98 SVT 03 Escape Limited