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Engine causing servo glitches

Old 09-15-2007, 11:53 AM
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NLAT
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Default Engine causing servo glitches

Hello every one I have a Fuji BT-64 on my 1/4 scale extra, I am glitching when the engine is close to idol. I have made sure there is no metal pushrods between engine and servos. all engine wires are up front as well is the engine battery. Flight control reciever and batteries are secure and have no movement. I have also changed the reciever, glitches are still there. Now here is the question, Will the new spread spectrum get rid of the engines enterferance. Of course any ideas are welcom. Thanks
Old 09-15-2007, 12:58 PM
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kwilliby
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Default RE: Engine causing servo glitches


ORIGINAL: NLAT

Hello every one I have a Fuji BT-64 on my 1/4 scale extra, I am glitching when the engine is close to idol. I have made sure there is no metal pushrods between engine and servos. all engine wires are up front as well is the engine battery. Flight control reciever and batteries are secure and have no movement. I have also changed the reciever, glitches are still there. Now here is the question, Will the new spread spectrum get rid of the engines enterferance. Of course any ideas are welcom. Thanks
I'm not sure if Spektrum will cure it or not.

But by chance do you have a resistor plug? And do you have a metal spark plug cap?
Old 09-15-2007, 01:25 PM
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Tired Old Man
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Default RE: Engine causing servo glitches

Better and a lot cheaper to locate the source of the glitch. If your engine has a mag, (yours does not since you noted engine battery) make sure it's properly grounded and you're using the correct plug. If you have an ignition with a grounding strap, relocate the end of the strap to the cylinder head by drilling a small hole in the top fin and affixing the strap with a screw and nut. Likely you have it attached to the mounting plate on the back of the engine. That's very often a poor ground. Again, use the correct plug. Resistor type plugs in both cases, one with an "R" in the part number.

Next clean all the servo and extension connectors to remove any tarnish that may be there. Next use a piece of tape to secure the crystal in the end of the receiver. Did you use an old, previously used switch? Replace it (them?) with new. Now make sure the ignition battery has a full charge on it. A low ignition battery can cause glitching, and of course rough engine running. Check the landing gear mounting screws to see if they are tight and secure. Use Locktite to assure they remain secure.
Old 09-15-2007, 03:53 PM
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NLAT
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Default RE: Engine causing servo glitches

Thanks for the advice. All the servos and extensions are new, I will look at the plug, it came with the motor, also new. I'll also relocate the ground, it is located on the back plate. i'll give it a shot, can't get any worse.
Old 09-15-2007, 04:00 PM
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Default RE: Engine causing servo glitches

OK i just checked the spark plug the part # is Champion RCJ6Y.
Old 09-15-2007, 04:31 PM
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Tired Old Man
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Default RE: Engine causing servo glitches

Plugs good if it's not worn out. I'm betting on the ground, which was why I mentioned it in the beginning. Seen this too many times before.
Old 09-15-2007, 05:13 PM
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Default RE: Engine causing servo glitches

If you have a metal boot on the spark plug try a hose clamp around the base of the metal cap. You can get them at an auto parts store. They are about 1/4" wide and used for fuel line's.

I had a horrible glitching problem on a 60cc engine. It would only glitch at mid throttle. WOT and idle were fine. The metal cap on the plug was just loose enough to vibrate against the spark plug and cause metal-metal noise that drove the receiver nuts. Only way I found it was by getting the engine at the right rpm to cause glitching, then twisted the metal boot back and forth. A little hose clamp fixed my problem for good.

It's very easy to try and cheap. Hose clamp is about 50 cents.
Old 09-15-2007, 08:50 PM
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Default RE: Engine causing servo glitches

Location of the reciever antenna can have a lot to do with glitches, case in point, my PAU Edge 540. If I run the antenna through the nice tube in the fuselage, the thing goes nuts. Poke a hole in the covering in the bottom of the fuselage, tape it to the bottom, no more glitch. Have done this twice on the same airplane and I got the same results both times.

I hated to poke a hole in the covering, but what the hay, it worked!!!LOL!!

Dale
Old 09-15-2007, 10:58 PM
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Default RE: Engine causing servo glitches

i already tried that, had no effect. i even changed the reciever.
Old 09-16-2007, 07:23 AM
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Default RE: Engine causing servo glitches

NLAT,

Any particular surface getting the glitch? I've got the same thing going on, at a certain RPM my rudder goes 40 degree's left. If I wiggle the stick a couple times, I get it back, but it's only the rudder and a certain RPM? changed receivers, no change either.
Old 09-16-2007, 11:35 AM
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Default RE: Engine causing servo glitches

yes it is always the same. most of the glitch is in the rudder, but also a little aileron, and throttle. it all happens at the same time, but more promanent in the rudder.
Old 09-16-2007, 11:48 AM
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Default RE: Engine causing servo glitches

try "soft mounting" the receiver. don't strap it down tight. put lots of foam and strap it in loose.
Old 09-16-2007, 01:12 PM
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Default RE: Engine causing servo glitches


ORIGINAL: NLAT

yes it is always the same. most of the glitch is in the rudder, but also a little aileron, and throttle. it all happens at the same time, but more promanent in the rudder.
Maybe you indicated earlier...do you have the metal spark plug cap?
Old 09-16-2007, 02:35 PM
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Default RE: Engine causing servo glitches

my receiver is mounted in a SmartFly Power Expander with rubber grommets, not allot of cushion, wonder if that's it? I should call them Monday.

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Old 09-16-2007, 02:37 PM
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Default RE: Engine causing servo glitches

I'll do this one more time. Re-locate the ground to a stable location. The issue you are having has been all too common with people that have ground straps attached to the engine mounting bolts. Many have argued the point, they even do some other very odd things to attach the ground strap. Later they send the ignitions and/or the engine back for a "fix", only to find out when it's returned there's nothing wrong. Just their workmanship. Doesn't matter what type of engine it is. If the ground is improperly attached you will have glitching.
Old 09-16-2007, 06:03 PM
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Default RE: Engine causing servo glitches

ok pat i took your advice and relocated the ground to, as suggested, the fins. i started the plane and the problem is exactly as it was before.
Old 09-16-2007, 07:52 PM
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Default RE: Engine causing servo glitches

Damn! Go to Kwillby's note. The metal clips inside the plug cap could be loose.
Old 09-16-2007, 08:59 PM
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Default RE: Engine causing servo glitches


ORIGINAL: Pat Roy

Damn! Go to Kwillby's note. The metal clips inside the plug cap could be loose.
That's where I'd put my money at this point. The cap can even feel tight, but get just the right vibration from the engine and the cap can vibrate against the plug and cause grounding problems or metal-to-metal noise that will drive the receiver nuts.
Old 09-16-2007, 09:32 PM
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Default RE: Engine causing servo glitches


ORIGINAL: NLAT

ok pat i took your advice and relocated the ground to, as suggested, the fins. i started the plane and the problem is exactly as it was before.
NLAT, have you made sure your plug connector is pushed firmly onto the sparkplug. I have seen several times where guys just push it part way on, the connection to the plug is not secure and the resulting spark at the connection causes radio interference.
Old 09-17-2007, 08:22 AM
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Default RE: Engine causing servo glitches

may I give asuggestion, I had a hanger 9 extra 260 w/ a fuji 50 and it also glicht when started it turned out that in one cable keeper I had servo and ignition cabels close together.so I seperated ignition cables and sevro cables ignition cables on the right side and the servos on the left side and it stoped the glitches.
Old 09-17-2007, 08:55 AM
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Default RE: Engine causing servo glitches

Go to 2.4GHZ and forget it. You have tried everything else
Old 09-17-2007, 10:01 AM
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Default RE: Engine causing servo glitches

no one has asked how much separation you have between ignition parts,batteries,switches and so on from your radio setup,i try to get all the space between them as i can.even the ignition battery can cause this if it is too close to any radio stuff.an old servo can also have a bad pot in it and be the problem
Old 09-19-2007, 12:14 PM
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Default RE: Engine causing servo glitches

Dude before you go buying stuff try seperating ignition cables battery isolate the radio stuff on one side of the plane and the radio stuff on the other side and get plastic cable isolator from autozone and make sure you do'nt have broken cable wires from servos or extencions and make sure your reciver has a pice of foam under it and tied down.the problem has to be some where I sure of it.it sure beats buy a new radio and reciver and what if you buy radio and reciver and still glitches after all???
Old 09-19-2007, 04:11 PM
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Default RE: Engine causing servo glitches

Worn out servo´s potentiometer and potentiometer viper causes glitches. So you need replace servo and see does it help.
Old 09-24-2007, 09:29 AM
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Default RE: Engine causing servo glitches

Hello,

Have you solved the problem yet? Im having the same problem with a Fuji BT-32 EIS mounted in a new Giant Super Sportster, all surfaces glitch but the throttle really go nuts, I have moved the throttle servo back past the fuel tank and the ignition battery and switch way foward with no luck, my module is still mounted to the firewall above the engine with screws (will soft mount this next) other than that Im at a loss.This is my first gas plane, but have set up many others with success.

Thanks, Jim

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