My EGT's have risen 100 degrees!!

[Flybuddy2]

You didn't wrap any of the exhaust pipes recently, did you?? During annual, I wrapped one that was close to the fuel transducer. Was scratching my head afterwards why that one cylinder went high on egt only. I pulled top cowling to investigate, looked at the wrap and went DUH!!

[Bubblehead]

Here's a link to the Alcor document in the post title. http://www.alcorinc.com/pdf/netsc013.pdf

It says the following:

EGT symptom: 75 - 100 rise for one cylinder
Probable cause: Spark Plug not firing due to fouling, faulty plug, lead or distributor.
Recommended Action:
1) Enrich mixture to return EGT to normal
2) Go to single mag operation. When mag firing the bad plug is selected, EGT will drop suddenly, defining plug is not firing

I think the trouble shooting is the same for two plugs not firing, but to do the mag test it will need to be in the air when the EGTs are high so you can see the change.

[pierre smith]

Originally Posted by AlexPeterson

Pierre - is it possible that the two cylinders are both on the same Lightspeed coil? If so, that coil might be flaky. Since it is a wasted spark system, each coil fires two cylinders.

I connected with Klaus at Lightspeed and also noted that cylinders 3 and 4 do indeed share the same coil...the cylinders with the high EGT and cooler CHT's.

I have two coils shipping overnight....one as a spare.

Thanks guys...I'll let you know tomorrow evening.

[sprucemoose]

Pierre,

Just curious- where are the coils mounted on your installation? Are they atop the engine, or outside the plenum in the "cool" area. And how many hours are on the installation when the coil failed?

[pierre smith]

...of the engine, towards the rear. I have two on the way, one as a spare since they're only $89 each. The "brain" is inside the airplane behind the instrument panel. The airplane and engine have around 350 hours total.

Klaus asked me if I'd checked my ignition systems in flight and I said no and that they had checked good during the 1800 RPM mag check.

Interestingly, he said that you troubleshoot a problem while you're having the problem, not when there's no problem!! Ray, my friendly A@P/IA buddy and I had to think on that for a second or so but Klaus has a good point.

I decided to fly the 24 miles back home at reduced power settings and interestingly, at 22" and 2300 RPM, there was no problem and I leaned down to 11 GPH on the Dynon 120 and all EGTs were very close. I was also getting a surprising 14.5 miles per gallon with a slight headwind.

Don, at Airflow Performance had told me a few weeks ago to lean to the most efficient point..MPG. At that point, however, I was going around 170 MPH and I said that that was all well and good but I didn't buy this fast airplane to go slow! It was a good learning experience though, showing that I can get very near the hourly fuel burn of my 0-360 in my old -6A.

Best,

[sjarrell]

Originally Posted by pierre smith

.... Klaus asked me if I'd checked my ignition systems in flight and I said no and that they had checked good during the 1800 RPM mag check.....

The guys at Advance Pilot Seminars (George Braly, John Deakins, Walt Anderson, et. al.) advocate doing your mag check at the end of each flight while you're still flying WOT and LOP for a couple of reasons:

1. They claim that doing a mag check while WOT LOP will uncover problems that a simple ramp check at 1800 rpm simply won't show as the ignition system is having to perform at its peak to ignite the fuel in this configuration.

2. If you do find something's wrong, you can get it fixed before your next flight instead of having to deal with it as you're ready to take off.

I certainly don't claim to be an expert on the matter, but I can repeat what the experts are teaching.

For anyone that hasn't been out to their seminar I highly recommend it. It's highly educational and a lot of fun.

Best regards,