Engine issue question

[uk_figs]

My ECI 0-360 has performed flawlessly for 280 hours until the last two flights, runup and mag check is fine after first start but after landing at the fly-in and sitting for an hour or so the left mag check runs rough. Tried clearing the plugs with no effect but when I got back home and did another mag check it was fine.

Tried the mag check in the air and #4 CHT falls so I assume this is the problem cylinder. Have not pulled the cowl and plugs yet but it got me thinking about the useful life of aircraft plugs (they are Champion and looked fine at the annual) and what the best plugs are to replace them with.

Appreciate inputs and plug recommendations ( no Pmag stuff as it is on the list at some time)

[JDanno]

I just had a similar situation: New engine, taxed around for about 15 minutes over several attempts while working on the brakes. First time attempting to take off the mags had a HUGE drop on both sides. Aborted take off and pulled and cleaned all the plugs. Checked them also as my A&P friend had a cleaner/checker gizmo. Two plugs looked a bit sketchy and replaced them. These were new plugs with only 15 minutes on them. Even after repeated cleaning they still weren't passing the electrical test.
Runs great now. Moral of the story seems to be that plugs can go bad very easily, even new ones. Clean the plugs and run the check and throw away the ones that are a bit sketchy.

[Fred.Stucklen]

Check the resistance of your plugs with an ohm meter. They shouldn't be much over 1500 ohms. Anything greater than that is a defective plug. And the Champions are know for this type of failure...... Replace them as fast as you can with any other brand!

Originally Posted by uk_figs

My ECI 0-360 has performed flawlessly for 280 hours until the last two flights, runup and mag check is fine after first start but after landing at the fly-in and sitting for an hour or so the left mag check runs rough. Tried clearing the plugs with no effect but when I got back home and did another mag check it was fine.

Tried the mag check in the air and #4 CHT falls so I assume this is the problem cylinder. Have not pulled the cowl and plugs yet but it got me thinking about the useful life of aircraft plugs (they are Champion and looked fine at the annual) and what the best plugs are to replace them with.

Appreciate inputs and plug recommendations ( no Pmag stuff as it is on the list at some time)

[RV10inOz]

The above post is wrong.

The plug resistance is a problem but the ideal limit is 5000 ohms and even after that the problem is not that debilitating so that is only part of the problem.

Check the gaps, they need to be 0.016-0.018"

I would ask more about the ground running and leaning in flight as well as the spark plug gap.

The best test of the ignition system is a LOP mag check in flight. All EGT's should rise.

Doing the taught full rich mag check on the ground is the least effective.

[scottmillhouse]

It is possible to be the mag too. I had a similar type problem that I was tracking for months. Turned out it was the mag coil. Worked fine when cold and until a stop then would misfire after getting heat soaked on the ramp. Would check out fine once engine was cool enough to pull cowl. It eventually failed for good.

[uk_figs]

My normal leaning procedure in flight is the old pull the mixture until runs rough and then richen until smooth. I try to keep the Dynon between Peak and RoP. As I have a carb I am not able to get the engine running smooth at LoP.

When I tried the mag check in the air the only indication that changed was on #4 (CHT dropped)

If it was a mag coil problem wouldnt that affect all cylinders?

Will pull the plugs this weekend and check, what are considered the best plugs?

[scottmillhouse]

I have mostly steam gages and only have one cylinder instrumented. Not sure about CHT. Mine did not change but EGT would go up about 100 degrees when coil dropped the mag and you had to slightly raise power setting to maintain cruise. I was at times flying on one mag but did not know it since ground checks were ok. I never thought of an in flight check. It was not identified until it dropped off after heat soaking for a stop and failed at runup. Not exactly your problem but it took a couple of months to figure out. For you if it was only one cylinder and one plug, I would suspect wires if not plug otherwise perhaps an internal mag problem distributing the spark to that plug.

[Bruce]

Figs,

Put some of that Black stuff in the gas and it will fix everything.

But check the plugs and torque on mags.

My nickel !!!

Boomer