quote:In other words, are there durability issues with smaller center electrodes (common with Iridium and with some platinum plugs) in waste spark systems? Does the smaller center electrode make it more difficult for the spark to “hit” its target? Also, what's with the sensor business?
Most platinum plugs have a tiny center electrode. Look at one and you'll see just a pin point of metal surrounded by ceramic insulator. On Saturns the plugs actually fire twice in a 4 stroke cycle. Once at the top of the compression stroke and once at the top of the exhaust stroke (waste spark). There is more energy in the spark at the top of the compression stroke. However at the top of the exhaust stroke, the polarity is reversed and the spark fires into the center electrode. The tiny center electrode isn't up to the task.
Sorry but WRONG.. Those engines you mentioned (completely different animals) also have CAMSHAFT POSITION SENSORS, which the ignition system uses to calibrate the timing. The "S" series Saturns do NOT. They use the weaker waste spark measured resistance to provide the calibration for the ignition timing. The use of a non-recommneded (platinum in this case) spark plug upsets that calibration value and results (in most "S" series) in a MISFIRE or misfire code being generated. Sherrill's take and description is 100% CORRECT.