P-Mag question. Possible misfire? - Page 2

nomocom · #11 09-27-2010, 01:20 PM

Quote:

Originally Posted by apkp777

I have had one cyl (#3) that the CHT runs cooler and has a higher EGT

Tony
Low cht, high egt sounds like energy leaving the cylinder rather than be used in the cylinder.

If this is a new development a wobble test would probably be a wise (aka the morning sickness test )

If it is normal temps, then can you do a gami lean test ? Doesn't matter if you have carb since the test is still useful for defining the fuel distribution. Maybe you are already familiar with the test, if not google is your friend

apkp777 · #12 09-27-2010, 01:43 PM

Quote:

Originally Posted by nomocom

Tony
Low cht, high egt sounds like energy leaving the cylinder rather than be used in the cylinder.

If this is a new development a wobble test would probably be a wise (aka the morning sickness test )

If it is normal temps, then can you do a gami lean test ? Doesn't matter if you have carb since the test is still useful for defining the fuel distribution. Maybe you are already familiar with the test, if not google is your friend

Thanks Stan,

I am not familiar with the Gami lean test, I will look into that. This issue has been present since hour 1. I suppose it's possible that it could be a valve issue. That is on the bottom of my troubleshooting list and one of the only things left to check. I agree the indications are that the cylinder is not running as efficiently as the others.

I should probably start a new thread, although it is possibly (though unlikely) a P-mag mis-fire.

apkp777 · #13 09-27-2010, 01:47 PM

Quote:

Originally Posted by lostpilot28

It is an occasional miss...pretty random, actually. Although at one point yesterday it happened within 10 seconds of each other. I hope it's not a sticking valve...my engine has 86 hours on it since new!

Did you check your P-mag harness? You should have 180ohms/FT and when you wiggle and twist the wire there should be no change. It is possible that you nicked a wire when assembling the harness and are getting some occasional arcing.

G3i Ignition · #14 09-27-2010, 08:20 PM

Quote:

Originally Posted by Steve Sampson

Sonny, since auto plugs are so cheap why not put 8 new ones in. If the problem goes away....solved. Clean the old ones, put them on a tester and keep the good ones as spares.

If not, I would take a look at the harness perhaps.

PS It raises a question I have never received a practical answer to. I am a bit leery of taking my auto plugs out to look at them because I can neither replace/anneal the washers. Any practical solutions....anyone?

Here a VA link to an earlier G3i post on inserts and auto plug removal. http://www.vansairforce.com/communit...&highlight=g3i

See ya @ LOE
Thomas S.

lostpilot28 · #15 09-28-2010, 07:55 AM

OK, just bought 8 new plugs. I didn't want to spring for the Iridium plugs, so I just went with the NGKs. I'll ohm out the wires this evening! Thanks for the help, fellas!

lostpilot28 · #16 09-29-2010, 05:55 PM

Hey Tony, I ohmed one of my plug wires and it came out to almost exactly 180 ohms per foot. It was 3 feet long...maybe a couple inches. It read 554 ohms.

Is the 180 ohms per foot a "maximum" value, or just what it's supposed to be?

apkp777 · #17 09-29-2010, 07:14 PM

Sonny,
I believe that 180 OHM is the approx resistance of the leads. I am sure it could be off be a few OHMS either way and still be fine. I think a nick would show up as a dramatic change.

I have made another flight and am convinced that the Iridium plugs are much smoother than the cheaper BR8ES. I have been able to run LOP for the first time and I attribute that to the plugs. I don't know if it would help but I think the plugs are a good choice.