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  #31  
Old 06-25-2013, 06:18 PM
RetiredRacer RetiredRacer is offline
 
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Location: Ipswich QLD Australia
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Like you Steve, we bought second hand P-Mags when we were building and they were wired up right mag fired the top plugs and the left the bottom (I think that's how they were). First engine start and mag check showed the left mag dropped 10-20 rpm more than the right mag. Ok, thought this was just different flame travel between the top and bottom plugs, but being a bit suspicious with second hand as to why the original owner sold them, I decided to purchase a new mag and a compete set of new leads from Brad at Emagair. Being in Australia I thought it was a good idea to have a spare anyway.
I never fitted the mag or leads as apart from the 10-20 rpm more mag drop they were performing perfectly for two years, then a mag check showed no rpm drop on the right mag and 70 rpm drop on the left (normally it was 20 rpm drop on the right and 30-40 on the left).
Ok, time to fit the new mag, timed it and fitted the new leads to the new mag only. Started up and did a mag check, Holly ****!!! It ran sick as **** on the left mag!!! Pulled the new leads and refitted the old ones. The old leads were tied up as a loom and slipped straight on the mag with out having to work out where they fitted.
Another mag check and it was back to it's old self of 10-20 rpm more drop on the left mag. It ran nice for about ten hours, then it started dropping more rpm on the left mag. Pulled the leads and ohm checked them, two leads were way out (****, why didn't I check them before???). Ohm tested the new leads, perfect!!
Not being able to get the head in behind the motor to read the lead numbering on the mag the first time I fitted them, I used a mirror to read them. Thinking I may have somehow got it wrong by a "mirror image" affect the first time I fitted them, So this time I used the the old mag to locate the leads on the new one (why didn't I think of that before. I also I replaced all the leads on both mags and wired them up two to the top and two to the bottom. She now runs perfectly and has for 30 odd hours with both mags dropping 30 rpm each.

Bob

Last edited by RetiredRacer : 06-25-2013 at 06:26 PM. Reason: Trying to find a word it will accept.
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  #32  
Old 06-25-2013, 10:48 PM
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petehowell petehowell is offline
 
Join Date: Jan 2005
Location: MN
Posts: 2,269
Default Wire connectors

Steve,

Check the power and signal wires and connectors very well. I had a similar issues and was completely flummoxed until I checked wires, snugged the screws and cleaned and reseated the connectors.

I put in new plugs, made new wires....nothing worked until we took a look at the connector. I don't understand why, but it was the issue.

Same as you, the engine sounded "wrong" (technical term).

No idea if this is worth anything - but wanted to throw it out there.
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  #33  
Old 06-26-2013, 09:55 AM
steve91t steve91t is offline
 
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Location: Huntersville, NC
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Quote:
Originally Posted by petehowell View Post
Steve,

Check the power and signal wires and connectors very well. I had a similar issues and was completely flummoxed until I checked wires, snugged the screws and cleaned and reseated the connectors.

I put in new plugs, made new wires....nothing worked until we took a look at the connector. I don't understand why, but it was the issue.

Same as you, the engine sounded "wrong" (technical term).

No idea if this is worth anything - but wanted to throw it out there.
Thank you, we will definitely check the connections.
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  #34  
Old 06-26-2013, 10:33 AM
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schristo@mac.com schristo@mac.com is offline
 
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Location: WA
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Default Connectors...

I will echo what Pete said... I had a bad mag check and found that my right pmag was way out of time. On inspection the power wire in the screw down 'computer type' plug was no longer firmly attached and the hold down screw had backed off. I reattached, and retightened all of the connectors, retimed the pmag and all was good again.
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  #35  
Old 06-26-2013, 10:59 AM
gasman gasman is offline
 
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Quote:
Originally Posted by schristo@mac.com View Post
I will echo what Pete said... I had a bad mag check and found that my right pmag was way out of time. On inspection the power wire in the screw down 'computer type' plug was no longer firmly attached and the hold down screw had backed off. I reattached, and retightened all of the connectors, retimed the pmag and all was good again.
This connection is the main reason I won't consider pmags till it is improved.

If I recall right, a "way out of time" mag can damage the motor.... Am I wrong here?
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  #36  
Old 06-26-2013, 11:26 AM
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Brantel Brantel is online now
 
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While not common on aircraft, that type of connector is very common in the industrial automation world. I have seen literally thousands of them in my career on all kinds of machines and equipment. Both in non moving static as well as high vibration applications.

I would not judge the Pmag based on that connector alone. Yes they can have bad connections but show me an affordable connector that never fails or that never needs maintenance....

When I first put in my Pmag, I kept a close eye on this connector every time I had the cowl off I would check the tightness of the wire hold-down screws and the connector hold down screws. Never found one loose so I now only do it occasionally.

If I were EMagAir, I would put an inexpensive 9 pin Dshell connector on there and lose the stigma associated with those phoenix connectors even if they are not a real problem.
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Last edited by Brantel : 06-26-2013 at 11:35 AM.
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  #37  
Old 06-26-2013, 11:40 AM
steve91t steve91t is offline
 
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So there are two small flat head screws that hold the connector to the mag, but there is another connection? There are wire hold down screws?
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  #38  
Old 06-26-2013, 11:46 AM
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Brantel Brantel is online now
 
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Quote:
Originally Posted by steve91t View Post
So there are two small flat head screws that hold the connector to the mag, but there is another connection? There are wire hold down screws?
Yep...from the manual:

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Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
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  #39  
Old 06-26-2013, 12:12 PM
steve91t steve91t is offline
 
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Right, but that's it, right?
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  #40  
Old 06-26-2013, 12:28 PM
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Toobuilder Toobuilder is offline
 
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Yes, thats it... Two screws
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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