The name "Camry" is an anglicized interpretation of the car's original nomenclature "Kanmuri," which means "crown" in Japanese. Little could Toyota have known when it introduced the car in 1982 how appropriate that name would become, as the Camry would eventually be crowned the king of compact sedans in America.
The basic purpose of any automobile's ignition system is to ignite the air/fuel in the cylinders. Three basic parts comprise the ignition system: the triggering mechanism that sends energy to the spark plugs, the ignition coil that amplifies the triggering energy to create a powerful spark and the spark plug that receives that energy to make the air/fuel mixture detonate. The shorter the distance between the ignition coil and plug, the less energy the system loses through resistance in the wire.
Ideally, a spark plug should be connected directly to the ignition coil so that every bit of the coil's energy goes into creating a spark. This wasn't practical on older, distributor-driven cars; the distributor itself was the weak link in the system, so the gains would have been minimal. It wasn't until the mid-1980s that computers and magnetic sensors were cheap enough, powerful enough and sophisticated enough to detect crankshaft position and trigger the coil without a distributor. Once these were mass-produced, manufacturers began using a computer to trigger multiple coils in a "coil pack." Each coil provided energy to two cylinders.
Direct ignition is an evolution of coil-pack ignition and uses a single coil mounted directly to the back of the spark plug instead of one coil for every two cylinders. Direct ignition is the most theoretically perfect ignition possible with today's technology, offering a very powerful, computer-controlled spark without relying on a single moving component. The Camry doesn't actually use a coil pack; it has direct ignition with one small coil-pack-style coil per cylinder.
One of the direct ignition system's strongest trump cards is that it uses solid-state technology. There are no moving parts to wear out; even the crankshaft position sensor is fully magnetic, so it can't wear out through normal use as a mechanical component would. Aside from computer failure, the only way that a direct ignition system can fail is if the coil itself internally shorts out or something happens to the wiring between the coils and the computer.
If you suspect ignition coil failure, simply unplug the wiring harness from the top of the plug and see if the engine changes pitch or idle quality. Of course, the Camry's on-board diagnostics system will already have detected a coil malfunction and triggered a check engine light, so this might action might not be necessary.
