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CJcanuck
Joined: 05 Jul 2006
Posts: 39
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 Posted: Fri Jul 15, 2011 2:50 am Post subject: Ignition woes |
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I'm at my wits end here. I've been chasing an ignition issue that first appeared when the aircraft was flown into some heavy precipitation. Basically we have a smooth running engine on start-up, with the proper mag drop and everything, but after 30 min or so the engine begins to run noticeably rough. Checking the mags will then show a 300-500rpm drop on the #1 position (#2 is fine).
We've installed Barry Hancock's auto-ignition kit, had a new mag installed, replaced the P-wire connector and ground plate on the bottom of the mag. Where should we go from here?
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Dale
Joined: 30 May 2007
Posts: 178
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| Posted: Fri Jul 15, 2011 4:15 am Post subject: Re: Ignition woes |
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since you changed over to auto plugs you might want to see if they are carbon fouling. if your mixture is on the rich side the back plugs might be carbon fouling. look at the plugs , should be a tan color. if any black or dark color then they are carbon fouling. check them against the front plugs carefully as there is a fine line between fowling and still working. For kicks you can put a hotter plug in just one cly to see if they change. The one to foul fastest is the number 6 as it gets the lions share of the fuel charge due to the supercharger design and carb placement. The exhaust pipe should be the same color as the plugs if all is running right so a black exhaust is over rich as well. Sometime the auto plugs when they get hot misfire if they have a cracked insulator or defect as well , dropped or hit with the wrench. your new issue might not be related to your old issue with the water.
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dsavarese0812(at)bellsout
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| Posted: Fri Jul 15, 2011 5:31 am Post subject: Ignition woes |
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What is the brand and model number of the plugs you are using? Here's
a test you can do.
Run the engine until it starts to misfire and immediately switch the mag
switch to the mag position that is misfiring and let it run on that mag
for 10 or so minutes. Then shut the engine down and using a laser
temperature sensor, "shoot" the temperature of every cylinder at the
same point on each cylinder and write the temps down. A good point on
the cylinder is just below the base of the spark plug. The coldest
cylinder is the one that is misfiring. Now you have narrowed it down to
the particular cylinder and spark plug. From there it can the plug, the
wire or the magneto cap. Also check inside the cap for possible cracks
and carbon traces. If you want, you can send me a close-up photo of
inside the cap. If there is anything unusual, I'll be glad to let you
know what I see.
Dennis
A. Dennis Savarese
334-285-6263
334-546-8182 (cell)
Skype: Yakguy1
www.yak-52.com
On 7/15/2011 5:50 AM, CJcanuck wrote:
| Quote: |
I'm at my wits end here. I've been chasing an ignition issue that first appeared when the aircraft was flown into some heavy precipitation. Basically we have a smooth running engine on start-up, with the proper mag drop and everything, but after 30 min or so the engine begins to run noticeably rough. Checking the mags will then show a 300-500rpm drop on the #1 position (#2 is fine).
We've installed Barry Hancock's auto-ignition kit, had a new mag installed, replaced the P-wire connector and ground plate on the bottom of the mag. Where should we go from here?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=346472#346472
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richard.goode(at)russiana
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| Posted: Fri Jul 15, 2011 5:49 am Post subject: Ignition woes |
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It sounds to me like a magneto coil-classic symptoms of running fine for 30
minutes or so then misfiring.
You changed a magneto-what about the other?
Also,are you sure the coils in the "new" magneto were good??
Richard Goode
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
--
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dsavarese0812(at)bellsout
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| Posted: Fri Jul 15, 2011 6:01 am Post subject: Ignition woes |
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Richard is right. It does sound like it could be a bad coil.
Typically, coil failures show up between 20 and 40 minutes of a flight,
when the coil gets hot. Tests have proven a bad coil will start to
break down at around 60 Celsius and continue misfiring as the
temperature goes up.
A. Dennis Savarese
334-285-6263
334-546-8182 (cell)
Skype: Yakguy1
www.yak-52.com
On 7/15/2011 8:47 AM, Richard Goode wrote:
[quote]
It sounds to me like a magneto coil-classic symptoms of running fine for 30
minutes or so then misfiring.
You changed a magneto-what about the other?
Also,are you sure the coils in the "new" magneto were good??
Richard Goode
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
--
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yakplt(at)yahoo.com
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| Posted: Fri Jul 15, 2011 6:34 am Post subject: Ignition woes |
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This is one from out in left field.
Are you absolutely positively sure that you are troubleshooting the correct magneto? You said that you have a mag drop on the #1 mag and that the #2 is fine. You have also said you have replaced just about everything to do with that bad mag. Ok.....
Just for the heck of it, remove the P lead from the mag that you think is the number one mag. The one with the problem. Now connect an OHM meter between the P lead wire that you just took off and ground.
Go into the cockpit and operate the mag switch and cycle between the #1 and the #2 settings.
When you see the ohm meter indicate a direct short to ground, that is the mag you are turning OFF with the switch position you have selected in the cockpit.
The point here is that you have a left and right mag on the engine. You have a #1 and a #2 position on the mag switch. Which mag is SUPPOSED to be connected to the #1 and #2 position on the switches can actually differ from plane to plane. For example, the switch positions are reversed between the #1 and #2 mags between the YAK-52 and the YAK-50. It is very easy to reverse those wires at the mag switch as well. So if you have not already done it, make darn sure that what you THINK is the #1 mag, is actually INDEED the #1 mag.
Of course always be aware that with the P lead off the mag, you have a HOT MAG, and any movement of the prop could have serious consequences.
Anyway, this is probably not your problem, but it is darn sure worth checking.
--- On Fri, 7/15/11, A. Dennis Savarese <dsavarese0812(at)bellsouth.net> wrote:
[quote] From: A. Dennis Savarese <dsavarese0812(at)bellsouth.net>
Subject: Re: Ignition woes
To: yak-list(at)matronics.com
Date: Friday, July 15, 2011, 9:59 AM
"A. Dennis Savarese" <dsavarese0812(at)bellsouth.net>
Richard is right. It does sound like it could be a
bad coil.
Typically, coil failures show up between 20 and 40 minutes
of a flight,
when the coil gets hot. Tests have proven a bad coil
will start to
break down at around 60 Celsius and continue misfiring as
the
temperature goes up.
A. Dennis Savarese
334-285-6263
334-546-8182 (cell)
Skype: Yakguy1
www.yak-52.com
On 7/15/2011 8:47 AM, Richard Goode wrote:
> --> Yak-List message posted by: "Richard
Goode"<richard.goode(at)russianaeros.com>
>
> It sounds to me like a magneto coil-classic symptoms
of running fine for 30
> minutes or so then misfiring.
> You changed a magneto-what about the other?
> Also,are you sure the coils in the "new" magneto were
good??
>
> Richard Goode
> Rhodds Farm
> Lyonshall
> Hereford
> HR5 3LW
>
> Tel: +44 (0) 1544 340120
> Fax: +44 (0) 1544 340129
> www.russianaeros.com
>
> --
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