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Ignition Timing floating - very freaky!! Comments? 700 1986

posted by  someone claiming to be Tony on  Fri Sep 1 12:36 CST 2000 [RELATED]

Hi Friends, any input would be appreciated. 1986 740gle. To preface this, the Jetronic ECM(passenger's kick panel) and the Ignition ECM (above the drivers feet) were replaced. This is the craziest thing I have ever seen.

Car starts, idles low about 400rpm, and actually drives. I dle is not adjustable, i turn the knob, but no rise in rpms (maybe a little). The sensors all check out ok. While checking the timing with my timing light, the Timing Mark on the Flywheel keeps moving counter-clockwise all the way around the flywheel. No Kidding! Looks like a slow pinwheel or something. The only thing I can think of is the distrubutor (hall sensor) is changing value. Has anyone ever heard of such a thing. What is the sensor that controls the position of the timing mark. Many Thanks in Advance,

Tony.







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    Re: Ignition Timing floating - very freaky!! Comments? 700 1986

    posted by  someone claiming to be abe crombie on  Fri Sep 1 13:08 CST 2000 [RELATED]

    Your harmonic balancer is slipping. The timing mark is carried on the outer pulley which is rubber mounted from the inner crank bolted piece.

    You will need to replace it in order to get a correct timing adjustment if it is slipping while you watch as you describe.

    Chalk mark the inner piece and watch and see if the mark placed there does in fact stay still to confirm the balancer failure.







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    Re: Ignition Timing floating - very freaky!! Comments? 700 1986

    posted by  someone claiming to be Don Foster on  Fri Sep 1 13:06 CST 2000 [RELATED]

    You mean like the rubber donut's slipping?

    "...all the way around the flywheel..."

    I think you mean the front pulley. It's a "sandwich" assembly, with the outer portion (having the timing marks) attached to the inner portion—which is firmly engaged to the engine—by a rubber vibration isolator "donut."

    When the rubber-to-steel bond finally fails, the outer portion of the pulley can slip away from alignment with the crank, giving the appearance of wandering timing.

    Certain repair procedures, if done improperly, can tear this bond.






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