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PMAG System Hard to Start with Moisture

Hi All,

I have an IO-360 with dual PMAGs, 500 hours. NGK plugs with 250 hours on them.

Operation has been flawless up to now (hangared almost all the time), but circumstances have caused me to position my RV-8 outdoors for the last week (with intake plugs and a canopy cover keeping the rain out pretty well). It rained everyday, and this morning a warm front brought warm humid air after a cool night. My fuel sump check showed no water in the gas (100LL). When I peeked inside the oil access cover it was clear that condensed moisture was all over the engine, EMS box, ignition wires, etc. I use dielectric grease sparingly on the ignition harness boots (spark plug side only).Temp was 70 degrees after a 50 degree night, with high relative humidity.

I was able to get a solid initial start, which petered out after a second. That's not unusual, but there was a slightly different sound when it quit. Not the normal sound when there's just not enough fuel to keep it going (I worry about flooding the engine so I prime minimally ... with the electric boost pump the FF reads 8-12 GPH then settles down to 4 GPM and I turn it off). I believe the ignition system failed.

Thankfully, I upgraded to dual EarthX batteries last year. I ran the starter for 1.5 minutes oven the next 10 minutes, trying flooding procedures, etc. A single plug would occasionally fire, but it was more like a pop. No luck starting. Walked away until the warmer temperatures (hopefully) cleared the (presumably) moisture problem.

Returned 6 hours later after the warm, dry day had a chance to do it's magic, but had a lot of trouble:
1. Took a minute or 2 of cranking to get a plug firing.
2. Took another minute of cranking to get enough plugs to fire to start it.
3. After running for 3 minutes the mag check passed, so I know all plugs are working.
4. Ran it for 15 minutes to recharge the batteries. The starting problem seems totally attributable to moisture.

I've researched online and this does not appear to be normal, so I've attempted to identify potential problems, but I don't have enough experience to identify the culprit. Ideas, anyone? Is it:
1. Condensed moisture in the PMAGs that is limiting the spark?
2. Arcing shorts in the ignition harness or spark plug boots?
3. Deteriorated NKG plugs that are degraded by the moisture in the engine?

TIA for anyone who responds!
 
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Plug wires

If it were an auto, I would put money on plug wires shorting across each other or to ground. Spray with LPS. But, my airplane is still under construction and I'm no aviation expert.
 
250 hours on NGK plugs?? $20 to change em as an ez first step. I change mine at each oil change. I?d try changing them before I did anything else.
 
Have you checked your air filter? If it is a horizontal with the snorkel, the water can easily get to your air filter and make breathing difficult.
 
Max hours on the NGK plugs should be about a 100 hours! Really! I change mine at every conditional inspection. Change the plugs and your problem will probably go away!
Danny

Hi All,

I have an IO-360 with dual PMAGs, 500 hours. NGK plugs with 250 hours on them.

Operation has been flawless up to now (hangared almost all the time), but circumstances have caused me to position my RV-8 outdoors for the last week (with intake plugs and a canopy cover keeping the rain out pretty well). It rained everyday, and this morning a warm front brought warm humid air after a cool night. My fuel sump check showed no water in the gas (100LL). When I peeked inside the oil access cover it was clear that condensed moisture was all over the engine, EMS box, ignition wires, etc. I use dielectric grease sparingly on the ignition harness boots (spark plug side only).Temp was 70 degrees after a 50 degree night, with high relative humidity.

I was able to get a solid initial start, which petered out after a second. That's not unusual, but there was a slightly different sound when it quit. Not the normal sound when there's just not enough fuel to keep it going (I worry about flooding the engine so I prime minimally ... with the electric boost pump the FF reads 8-12 GPH then settles down to 4 GPM and I turn it off). I believe the ignition system failed.

Thankfully, I upgraded to dual EarthX batteries last year. I ran the starter for 1.5 minutes oven the next 10 minutes, trying flooding procedures, etc. A single plug would occasionally fire, but it was more like a pop. No luck starting. Walked away until the warmer temperatures (hopefully) cleared the (presumably) moisture problem.

Returned 6 hours later after the warm, dry day had a chance to do it's magic, but had a lot of trouble:
1. Took a minute or 2 of cranking to get a plug firing.
2. Took another minute of cranking to get enough plugs to fire to start it.
3. After running for 3 minutes the mag check passed, so I know all plugs are working.
4. Ran it for 15 minutes to recharge the batteries. The starting problem seems totally attributable to moisture.

I've researched online and this does not appear to be normal, so I've attempted to identify potential problems, but I don't have enough experience to identify the culprit. Ideas, anyone? Is it:
1. Condensed moisture in the PMAGs that is limiting the spark?
2. Arcing shorts in the ignition harness or spark plug boots?
3. Deteriorated NKG plugs that are degraded by the moisture in the engine?

TIA for anyone who responds!
 
250 hours on the plugs? Surely that's a typo. Regardless, change them so that you are starting from a fresh point. New dielectric and start. If that's a no-go call Brad and start a diagnosis with him. In 5 years I've had to send two P-mags back to the mothership for some momma lovin. It happens, but let Brad help you troubleshoot AFTER you change those worn out, worked like an unloved mule, beat down, exhausted plugs.
 
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Click and Clack troubleshooting tip,... if you think it is water

Really,...came from them... but it worked on my old reliable import that had turned into not so reliable, but not totally predictable. It would be less than reliable on wet or rainy days....

On a dry day,...Take a misting/spray bottle with water,...and spray suspect area(s). On my old car it was a bad wire/ connection from coil to distributor

Speaking of wires,..E-mag put out a note on some bad wires that did not properly engage the mag. Quick check was to pull on wire at mag and ensure it took a tug to get it loose. I?m guessing your setup is old enough that your wires were not in the suspect timeframe.

Good luck with sorting it out,....and please report back when you find the reason

Hopefully the E-mag experts will be along shortly and make some recommendations
 
Wire test

and all at the same time!

Much more likely to be the wires or other high voltage section of the system. Remember distributor caps?:)

Before high voltage ignitions, we used to run a finger along the plug wire. Bad wire would arc to your finger. It stung, but not horrible. No way I would do that with an electronic ignition.:eek: New cars don't even have plug wires anymore.

I have used a grounded screwdriver. Bad wire will arc big time. This is an airplane though and I wouldn't get that close to a prop. Maybe there's another way to check?

By the way, I just got a service letter from E-mag about plug wires. Probably not the issue but worth mentioning.
 
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