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  #11  
Old 01-03-2021, 05:47 PM
pilotkms's Avatar
pilotkms pilotkms is offline
 
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Location: WARNER ROBINS, GA
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U may want to buy a new set (2 sets) of wires from Emagair. When I got mine they were already assembled and have held up very well. I ohmed mine about 3 months ago and all 8 were within tolerance.
The plugs u should replace yours with are NGKs 3961. They are the same as yours but with solid tips.
Sounds like u are learning your plane. Good work.
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  #12  
Old 01-03-2021, 06:52 PM
Lt Dan Lt Dan is offline
 
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Here's an additional update - after seeing those broken clips, I started pulling terminal boots off. Here are some photos of the three that I pulled. Looks like every one of my terminals is bearing a striking resemblance to Bruce's. After that I decided to just purchase new harnesses...






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  #13  
Old 01-04-2021, 09:51 AM
lr172 lr172 is online now
 
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Quote:
Originally Posted by Lt Dan View Post
I also just got done putting an ohm meter to every ignition wire and the results I got were rather shocking. So much so that I dont know if this is actually possible. Two wires showed good resistance. ALL of the others showed open loops or nearly so. Could the engine have even run if this data is valid? Maybe my ohm meter couldnt complete the circuit, but the thousands of volts the P-Mags are sending could get the job done (barely)? Is that possible?
Yes. Your spark jumps an .035" gap on every event. However, this stack up of resistance will greatly decrease spark energy, so no suprise that there wasn't enough energy to consistently lit a lean mixture (They are harder to light than richer mixtures).
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  #14  
Old 01-04-2021, 10:14 AM
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E-mag had a SB a while back on plug wires. Might be worth a call.
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  #15  
Old 01-04-2021, 10:18 AM
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A good lesson for us all. Modern electronic ignitions will fire plugs, even with bad plugs and wires, up to the point where things go south. Check the wires and plugs at every annual.

With magnetos, I could watch the waveforms on my portable oscilloscope and determine a problem pretty quickly. I developed a gizmo that turn on a light whenever a plug fouled or a wire degraded, but a rough engine did the same thing. Electronic ignitions dont tend to have P-leads, so this is harder to do.

I bought a roll of spark plug wire, terminals and crimp tools from Summit Racing for DIY cables to fix some exhaust-burned plug wires on my Rocket. Cores were exposed, discovered at annual. Engine ran fine, but Im glad I caught it.

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  #16  
Old 01-17-2021, 07:14 PM
Lt Dan Lt Dan is offline
 
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Location: Utah
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Default Update - Not the Harness

UPDATE:

Unfortunately, the problem persists! The ignition harness was not the problem. I believe it was contributing to the roughness, however the roughness remains with the harness fixed.

I finally got to fly the plane with new terminal clips on the end of each wire. I bought 8 of them from Napa. For future reference the P-Mag wires are the 7 mm type (hard to find that data anywhere). I replaced each clip on each wire and all were then within resistance specs with solid connections all around.

Conducted another LOP mag check and the roughness persists. It was definitely better (smoother), but not fixed. On each mag, as EGTs rose, the popping and roughness quickly started again.

Back to the drawing board. I'm interested to hear your thoughts...
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  #17  
Old 01-17-2021, 08:14 PM
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Quote:
Originally Posted by Lt Dan View Post
UPDATE:

Unfortunately, the problem persists! The ignition harness was not the problem. I believe it was contributing to the roughness, however the roughness remains with the harness fixed.

I finally got to fly the plane with new terminal clips on the end of each wire. I bought 8 of them from Napa. For future reference the P-Mag wires are the 7 mm type (hard to find that data anywhere). I replaced each clip on each wire and all were then within resistance specs with solid connections all around.

Conducted another LOP mag check and the roughness persists. It was definitely better (smoother), but not fixed. On each mag, as EGTs rose, the popping and roughness quickly started again.

Back to the drawing board. I'm interested to hear your thoughts...
Did you re-time the mags? Sorry if you wrote this elsewhere and I missed it.
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  #18  
Old 01-17-2021, 08:46 PM
Lt Dan Lt Dan is offline
 
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Quote:
Originally Posted by Gash View Post
Did you re-time the mags?
Yes, I did. As specd in the installation manual. 0 TDC. Timing curve A, jumper installed.
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  #19  
Old 01-17-2021, 09:27 PM
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OK. I like that u are trying the mentioned suggestions. Ive never had the popping problem u mention. But I did experiment with different settings back in phase 1, 600 hours ago. I settled on timing my Pmags 1 tooth AFTER TDC with the jumpers IN. This lessens the advance by 2.4 degrees (I think ?). Seems to provide the smoothest run and best CHTs for my setup. U may want to try timing yours similarly. Start with 1/2 tooth less advance. As always, be careful and YMMV.
FYI - my LOP today due to Nozzle/Restrictor selection assistance from Don at AFP was 0.0 gph.
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  #20  
Old 01-17-2021, 11:25 PM
Lt Dan Lt Dan is offline
 
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Quote:
Originally Posted by pilotkms View Post
... U may want to try timing yours similarly. Start with 1/2 tooth less advance. As always, be careful and YMMV.
FYI - my LOP today due to Nozzle/Restrictor selection assistance from Don at AFP was 0.0 gph.
Thanks for the advice. Before I re-timed them about two weeks ago, I actually found that they were set to about where you described. 1/2 to 1 tooth less advance. Same results.

Impressive GAMI spread. How far are you able to run LOP (in terms of degrees)? Im only able to get 10-30 deg LOP before the engine runs rough at the present time. (Thats with mags on BOTH, of course.)
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