Quote:
Originally Posted by Detroit Bill
I took it out for a ride the stumble, miss, cutout was gone for several high 5,000 rpm shifts. Stumbled once. The difference between this and other tests was that the car was not as hot as usual. I thought I saw the tach take off once, hard to pay attention exactly at that RPM.
What else?
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It does not happen very often, but it does happen: the feedback from the
tachometer itself to the MSD box can cause a misfire. Obviously, the way you test this is to just pull the tach wire out from the MSD box and run it up to where the misfire occurs with the tach completely disconnected from the box. Now, mind you, this is a "low probability" event, but it's very easy to check assuming your misfire is relatively consistent and your ears are attuned. If you don't trust your ears, rely on your speedometer to tell you when the misfire occurs. For example, 60MPH in second gear. That will act as your RPM measuring device while your tach is disconnected.