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Multiple misfire just an anomaly?


Full Member
Jan 11, 2004
Gainesville, VA
I have an intermittent misfire problem.  Scanner shows misfires come and go on #2 and #7.  In each sample, the number of misfires changes, but #2 and #7 are always exactly the same number.  That's too coincidental for me.  Based on Sperry's explanation of how misfires are counted by measuring engine rpm variations throughout the rotation, I am suspicious.

I can't think of anything that is common to these two cylinders that would cause identical misfires.

#2 fires right after #7 in the sequence.  Is it possible I only have a misfire on #7, and that the scanner is just seeing #2 as a misfire because it takes a while for the engine rotational speed to recover when #2 fires?

BTW, the misfire goes away for a while everytime I go in and remove and reinstall the wires.  The wires look good, visually.  I went and bought one new wire.  I'm waiting for the misfire to come back, then I'll replace the #7 wire and see if it stops.  If not, I'll move the new wire to #2 and check again.