The engine computer is responsible for firing the ignition coil, and the crankshaft position sensor tells the computer when to do it, so if you have spark, leave them alone. They're doing what they're supposed to do.
It's important to know the characteristics of the spark you're getting from the coil. You should see a steady stream of strong sparks when cranking the engine. If that's what you get, but you don't have spark at the end of a spark plug wire, (which I assume is what you mean by "not from the distributor"), replace the distributor cap and rotor.
If you only see one spark when you turn the ignition switch off, you technically don't have spark, but it proves the ignition coil is good. The switching circuit in the engine computer could be at fault but that is rare. Chrysler had very little trouble with engine computers in the early '90s, but that's the first thing everyone blames when they don't know how all the other parts of the system work. The most common cause of a no-spark condition is the crankshaft position sensor which is the pickup coil in the distributor. They can be intermittent or heat-sensitive, but the air gap is also critical. .012" gap is perfect. One of my cars wouldn't start after the rotor was replaced. It was stuck, so I cracked it off with a hammer and chisel. When the rotor split, it pushed against the pickup coil creating an air gap of.018". That's an increase of two or three sheets of paper! The pickup coil is built around a strong magnet, so to get a proper feel when setting the gap, you must use a non-magnetic brass feeler gauge.
Caradiodoc
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Wednesday, February 10th, 2010 AT 12:01 AM
