A couple of days ago I posted about a problem with my #2 cylinder. Watching
my JPI EDM-700 in flight, the EGTs on #2 shot to over 1600 degrees, and the
CHT sank to 200 degrees. After trouble-shooting, it became apparent that the
condition became much worse when set on the left mag only.

In other words, the #2 cylinder was not firing -- or, at least, not firing
consistently -- when on the left mag. On "both", the only symptom was the
bar graph on the EDM -- the engine sounded perfectly normal.

Yesterday I removed BOTH spark plugs from the #2 cylinder (I figured "why
not?" as long as I was at it) and had my A&P test them in his pressurized
spark plug tester. Both were clean, and checked out fine.

He re-gapped them, and I reinstalled them. They were off, according to my
A&P, so I believe my next step will be to re-gap ALL the spark plugs.

I also sprayed the oil-saturated wiring harness down with contact cleaner,
which did a fine job of "de-greasing" them.

All connections appeared fine, although I didn't take the mag connections
off. I figure I'll take her around the patch when I get time, to see if all
is now well. (It WAS well on our way home, if you recall, after leaning
severely during a long run-up.)

My mechanic said what I did MAY fix it, if it was just a chunk of crud on
the spark plug causing it to mis-fire. But he also said it could be a bad
lead wire, or a bad distributor inside the mag.

Thanks to all who have responded -- is there anything else to check? I
find it hard to believe that I could have had a fouled plug, given the fact
that we usually burn unleaded mogas, but perhaps it's a plug that only fails
when hot?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"