Slide 23 of 123

The illustration above shows a typical waste spark distributorless ignition secondary circuit. The arrows show current in the secondary and demonstrate how the engine block completes the secondary circuit current path. When viewing this illustration consider the following:

1) Electricity always returns to its source.

2) One plug fires with positive polarity, the other with negative polarity. The plug closer to the coil negative secondary terminal requires less voltage to fire than the plug closer to the positive terminal. (Its easier for the spark to jump from the center electrode to the ground tab than the other way around!)

3) Prolonged opens in the secondary result in coil pack or module failures.

In waste spark DIS, all plugs fire twice per combustion cycle (720 degrees of crankshaft rotation). Both plugs connected to a coil fire at the same time on the power and exhaust strokes.

Plug firing on the exhaust (waste) stroke requires less energy to jump the plug gap than the simultaneous firing of the mating plug on the combustion stroke. (There is no compression factor to overcome in the cylinder on the waste stroke.) Compare combustion and waste firing voltages to locate high secondary resistance. Waste KV should always be much lower that combustion KV