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Dual Sync Distributor

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I am having some issues with a Holley (MSD) Dual Sync distributor. It has two hall effect sensors in it, four wire connections: +12, Ground, Crank Sensor feed and Cam Sensor feed. It appears the Crank sensor is going to lunch occasionally, which with the loss of a sync signal, the ECU stops doing its thing.

The issue is intermittent. Holley/MSD says they have very little info on it, and don't have any trouble shooting tips other than if the LED's are going off and on, then it's working. But you can't see the LED's when the engine is running or when it fails. Once everything cools down, things get OK till it happens again. I have kind of isolated it to when the engine heats up something happens to lose the ground on the sensors and I think the problem is in the distributor. All connections to it have been confirmed and verified, those only remaining are inside the distributor.

Has anyone ever torn into one of these and have any insight on the internals? Is the circuitry just a printed circuit border the mounts and splits the feed to the two hall effect sensors, or is there more on the inside that could go bad?

I have a replacement on order but would like to understand more about the failure. Vehicle ran fine the first 20 hrs of operation and has been an intermittent nightmare the last 15 hrs.

I would troubleshoot that with a lathe (or drill motor), heat gun and an oscilloscope.

That's actually very clever using a heat gun, never thought about it!

Sounds like a dry joint or broken trace?

We usually reply within 12hrs (often sooner)

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