First off, thanks to everyone who responded with colortune information. I
ended up getting it from Moss since I remembered I had an old $35
gift certificate. I discovered Gunson stuff is far cheaper in the UK.
I was pretty pleased with it when it arrived. Some parts looked a bit
cheap but upon closer inspection the spark plug and extender wire
turned out to be tougher than I at first thought. It came with a very
nice colour instruction sheet displaying flame colours and helpfull
tests and troubleshooting tips. Quite a few typos though.
Anyways, I tried it out on my '76 Rabbit with a Weber DFAV carb on it.
I have had an occasional miss at idle that has been really irritating
me for the past little while. The car runs fine on the main circuit,
always starts right away, doesn't backfire significantly on over run,
has nice chocolate coloured spark plugs, and is getting resonable gas
mileage.
I did the first test on the instruction sheet where you richen up
the idle till you see orange and then lean it into the blue again.
I found out I probably had set the idle a bit lean.
I then noticed that occasionally the "miss" would happen. I could
distinctly see each individual firing and every once in a while
there would be black when there should have been a blue flash. The
next flash would then be orange. This I reason is due to the rich
mixture composed of the remains of the previous unburnt mixture combined
with the new charge. I believe I did not see a spark during the miss.
My next debugging step tonight will be to hunt through the ignition
system measuring coil voltages, polarity, swapping coils, etc. to
see if I can find anything which would be causing a weak spark.
I'm interested in hearing about other peoples colurtune experiences and
whether what I am seeing is at all familiar.
Thanks again --rod.
--
Rod Barman, Dept. of E.E., University of British Columbia
rodb@salmon.ee.ubc.ca
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