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The Chilton manual for the late 90s and early 2000s Durango and RAM says that PCM controls ignition timing and spark advance. I don't understand this, because these motors are equipped with a standard spark-gap distributor. Because of the mechanical timing, the computer timing should be irrelevant.

  • Can someone please clarify what is going on with these dodge and similar engines?

  • What is the relationship between the PCM, the distributor system, and actual ignition control?

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While the vehicles are equipped with a distributor the innards of that distributor have changed quite a bit. The distributor no longer contains flyweights or any mechanical timing controls, instead it contains the camshaft position sensor.

The way the system works is, readings are taken from the crankshaft position sensor by the PCM. The PCM then calculates the needed timing and fires the ignition coil at the correct time. The distributor then directs the spark to the correct cylinder.

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  • Yes, this design goes back to the 1970's.
    – Fred Wilson
    Commented Dec 20, 2015 at 21:47

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