How Distributorless Ignition SystemS work
How Igniters work
How DIS works

How the Distributorless Ignition System works



A distributorless Ignition System does not have a distributor. The distributed timing signal is distributed from inside the ECU. Leaving the mechanical distributor out reducing the number of moving parts and improving reliability. Some of the benefits are:

  1. More control over the coil. There is more time buildup a substantial magnetic field to produce spark required to sufficiently burn the fuel and reducing misfires, in effect reducing emissions.

  2. Ignition timing is improved. Unlike a distributor, a DIS eliminates the chance of spark misfiring when too much advance is applied to the secondary voltage as often seen on distributor system..


Figure 3

The DIS sample above has one ignition coil with two spark plug wires for two cylinders. The coil is mounted directly to one spark plug. This is a method called simultaneous ignition (waste spark) where an ignition spark is delivered from one ignition coil for two cylinders at the same time. The other kind is the direct ignition system with independent ignition coils that has one coil per cylinder, such as the coil  on the left at the top of the page and figure 4.

Figure 3. The IGF signal warns the ECU of any cylinder misfires because it knows when each cylinder needs to be ignited. Fed by the crank, cam and various sensor the ECU determines the correct timing based on preset conditions for power, efficiency and emissions requirements.

Figure 4

Author's comment: These individual coil designs which plugs into the cylinder are pretty safe. In case they are damaged you might want to stay clear. Long ago I'd had the unfortunate luck of being zapped by a Camaro DIS system which is equivilent to the pain of a snake bite. Nonetheless, it was an experience to remember. The pain is unforgettable.

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