I agree with folks that suspect one or more bad plug leads. I had similar problem recently...darn near tore whole engine apart, plus replacing numerous parts trying to get problem fixed. All to no avail. I took all plug wires out...checked continuity and ohms etc...all seemed OK. But then a friend suggested I check plug wires when re-installed and engine running at NIGHT...with the plastic cover that goes over top of engine removed. Guess what? 3 of 5 of my wires were arcing to the engine block. Cause? Wires were old and bakelite plastic insulation had deteriorated allowing high voltage to jump to the engine block.
Upon closer inspection - after cleaning wires - I noticed small spots/holes around shoulder of plug holder where electricity had burned through plastic and rubber insulation.
Now with new plug wires all is OK.
Good luck.
|