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  #1  
Old 04-03-2019, 08:31 AM
jump4way jump4way is offline
 
Join Date: Sep 2008
Location: Coolidge, AZ
Posts: 348
Default Ignition Noise

I'm looking for some ideas to squash an ignition noise issue I'm having. I'm able to isolate the noise by shutting off one ignition and the noise goes away. The noise is a steady tick tick tick noise that has an increase in cadence as rpm increases. The oddity is that If I turn on my aux input battery powered bluetooth module, the noise goes away.

Things I've tried are:
1) ferrite cores on the power leads.
2) two types of noise filters with the offending ignition power wired through.
3) replaced spark plugs (using solid tipped automotive spark plugs)
4) Ohm tested each of the ignition leads for proper resistance. They all checked out to show appropriate resistance for the given length. I also slightly twisted and rotated the leads as I checked the ohm reading to see if anything seemed amiss.
5) crimped each of the spark plug connectors to ensure good contact.
6) put dielectric grease on each of the spark plug caps.
7) checked the spark plug gaps.

Any other ideas any0one might have?
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  #2  
Old 04-03-2019, 09:09 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,234
Default

Check all ground wires on the whole aircraft for good terminations.
Make sure that the audio and mic jacks are mounted with insulating
step washers so that the jacks do not touch the airframe.
Quote from Bob Nuckolls' pdf:
Quote:
p-lead shields should
be grounded to the airframe/engine only at the engine end. The
shield is used to provide a ground for the "GRD" terminals at
the switch but no other connection to the shields should be
made at the instrument panel end.
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RV-12 Flying
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  #3  
Old 04-03-2019, 10:41 AM
jump4way jump4way is offline
 
Join Date: Sep 2008
Location: Coolidge, AZ
Posts: 348
Default

I'm using an electronic ignition but I suppose it's the same idea with the ground for the ignition coil in that it should be grounded at the engine. I currently have it grounded on my forest of tabs ground bus. I'll try a temporary ground to the engine and see if that makes a difference.

I have checked ground terminations and jacks for their respective shoulder washers.

Thanks for the ideas, please keep them coming.
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  #4  
Old 04-03-2019, 06:25 PM
jakej jakej is offline
 
Join Date: Aug 2005
Location: Adelaide, Australia
Posts: 158
Default Ignition noise

If it?s an LSE system then the forest of tabs works or if P-Mags ground directly to the engine, that?s always worked for me however follow the manufacturers instructions in the first instance
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  #5  
Old 04-03-2019, 07:21 PM
molson309 molson309 is offline
 
Join Date: Jul 2009
Location: Longmont, CO
Posts: 253
Default

Quote:
Originally Posted by jump4way View Post
-snip-
The oddity is that If I turn on my aux input battery powered bluetooth module, the noise goes away.

-snip-

Any other ideas any0one might have?
I once worked with a guy that had a similar problem. He had a music input - a mini phono plug on his instrument panel - that picked up noise when nothing was plugged into it. We fixed the problem by making a terminating plug that had a resistor inside shunted across the input terminals.

Audio inputs tend to have very high impedance when nothing is connected to them, which makes them susceptible to picking up electrical noise. Loading them by connecting a lower impedance source "fixes" this.

You can test this theory by terminating your aux input with a resistance. As an experiment try just shorting the input terminals together. If that works you may be able to find a resistance value that when left shunted across the input stops the noise but doesn't cause attenuation of the audio signal from your Bluetooth module.

Good luck!
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  #6  
Old 04-03-2019, 07:34 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,313
Default YMMV, but

I had the same tic with one of my mags (two slick mags) and it turned out the wire was slightly loose on the mag. It still shut off just fine. After buying a new capacitor, removing and tearing apart the mag and installing, that is what I discovered.

Slick parts are really expensive.

Good luck.
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RV-7
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  #7  
Old 04-03-2019, 09:24 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 12,887
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You never said what type of igntion you are running but did mention auto plugs.

Do you have dual electronic igntion? If so, what type?

Do you have a mixed ignition environment? If so, please describe.

If running auto plugs, what plugs and plug wires are you running?

Can you broadcast over your radio and be heard clearly?
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RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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  #8  
Old 04-04-2019, 06:37 AM
jump4way jump4way is offline
 
Join Date: Sep 2008
Location: Coolidge, AZ
Posts: 348
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Quote:
Originally Posted by N941WR View Post
You never said what type of igntion you are running but did mention auto plugs.

Do you have dual electronic igntion? If so, what type?

Do you have a mixed ignition environment? If so, please describe.

If running auto plugs, what plugs and plug wires are you running?

Can you broadcast over your radio and be heard clearly?
I'm using the SDS ignition system which is a dual electronic ignition system.

I am using the BR8ES 6391 plugs ( I think this is right... just going off of memory) with MSD plug wires.

I've had no complaints regarding transmissions.
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  #9  
Old 04-04-2019, 06:45 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 6,104
Default

If you have a hand-held VHF radio, you can check and see if the noise is on that too as it will be isolated from ship's power and grounds.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 450.6 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
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  #10  
Old 04-04-2019, 06:46 AM
jump4way jump4way is offline
 
Join Date: Sep 2008
Location: Coolidge, AZ
Posts: 348
Default

Quote:
Originally Posted by molson309 View Post
I once worked with a guy that had a similar problem. He had a music input - a mini phono plug on his instrument panel - that picked up noise when nothing was plugged into it. We fixed the problem by making a terminating plug that had a resistor inside shunted across the input terminals.

Audio inputs tend to have very high impedance when nothing is connected to them, which makes them susceptible to picking up electrical noise. Loading them by connecting a lower impedance source "fixes" this.

You can test this theory by terminating your aux input with a resistance. As an experiment try just shorting the input terminals together. If that works you may be able to find a resistance value that when left shunted across the input stops the noise but doesn't cause attenuation of the audio signal from your Bluetooth module.

Good luck!
Hmm.. interesting idea. I'm not sure I'm 100% clear on how you would wire the resistor. If I remember right, the plug is a stereo plug with 3 conductor wire so would I wire a resistor in line with each wire to the aux input?

Andy
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