Michael---These "misfires" are irritating, at best. I can't offer
anything in the way of solving the problem, if it's related to the PI
system. However, it does seem strange that a mechanic would turn the car
back over to you knowing that he didn't install plugs with the "right
heat range".
You said you want to experiment yourself. If you are either patient or
lucky, you can try a couple of things. When the engine is obviously
"running on five" try to isolate the dead cylinder by pulling off the
plug wires, until you find the one that makes no difference in the idle
speed, or engine smoothness. (It would help to have a vacuum gauge
connected to a good vacuum source, to note further drop in the reading)
This will at least give some clues as to whether it is that particular
injector, plug wire, plug, or ignition cap that is respnsible.
The CRANE ignition must be considered part of the loop, also.
An inductive type timing light connected to each plug wire, in
succession, can tell you if the spark is not consistantly getting to
every wire. If the misfire and "no flash" co-incide..bingo! You've just
narrowed it down some. (The flash can occur even when the plug is bad,
and no fuel was present to light)
Give some thought as to the distributor cap having a crack. Check it
closely. (Something caused the [old] rotor itself to crack.) Listen for
arcing in this area. If you hear it and can't see it, try again when
it's dark. If it's under the cap, get a spare, and drill holes all
around it to see inside. (Always entertaining)
Lastly, the plugs you yourself had just installed were probably the
resistor type. They're OK, if they're hot enough to keep from fouling.
Note, the plug color should tell you a lot as to how the injectors are
flowing, but it's necessary to stop the frequent misfire for this to be
a valid test.
Good hunting!
Dick
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