Need help with elevator only glitch while engine running.

[sthudson]

After a couple of successful flights today, I noticed my elevators started glitching while I was warming up my engine. Turned off the engine and the problem went away. Each elevator half is on it's own channel, and each one would glitch at different times. I turned the radio off and watched them while in fail safe mode and they still glitched randomly.
Now here's why I'm really puzzled. Last weekend I noticed weird things happening while warming up the plane (engine running). I was using PCM in my JR 8103. Have used it for a couple years problem free. I noticed it mostly on the ailerons. There would be delays in their response and they would hold position. So I thought it was losing signal and going into fail safe (last position). I figured this would give me a good excuse to get a 2.4 spectrum model and new 7 ch receiver. Binding was easy, range test was great, and I had several good flights today, but then it started acting up on the elevators only. Any ideas?? Here is my setup:

BME engine with CH ignition
Ignition modified for 7.4v lipo (no regulator)
Dual 7.4 lipo batteries with 6v regulators for receiver
JR 86100 servos on all surfaces
8103 radio w/ spectrum module
Spectrum AR7000 receiver
Thanks for your help,
Scott

[wfield0455]

If you don't already have one I would recommend picking up a data log for the AR7000 and seeing if it is detecting any significant # of antenna fades, etc..

Since it only happens with the engine running it seem it has to be related to that. Electrical noise from the ignition seems rather unlikely with 2.4Ghz but the data logger should give some feedback on that.. My best guess would be vibration from the engine???

[nate428]

are the servo wires/extensions twisted? any other electrical devices that the servo wires run by?
have to ask, but are you sure its a glitch and not the jr jitter problem?

YouTube - Broadcast Yourself.

[sthudson]

Thanks for the replies.

No the extensions aren't twisted. They run down the bottom of the fuse and are the only wires in that area. They have been that way for two years before the problem started. It's not the JR jitter. My rudder does that a little (not near as bad as the video). Each elevator half does it random, at different times. I was thinking ignition or something causing more vibration, so I took it all apart today and didn't find obvious. Although I did notice that one spark plug was nice and tan, and the other very dark. Maybe an ignition problem on one cylinder? I'm going to send my ignition to CH and have it checked out. I might send the engine to BME to have it gone through as well since everything is apart and it's been a couple seasons...

[rwedel]

Just a question,

Where is your Ignition located ?

Is your spark plug wire (s) touching the muffler (s) ?

Even if it is 2.4, their is still potential problems that can occur.

[sthudson]

The ignition is on top of the engine box. The plug wires run to the the top of the engine box, while the mufflers are below. Here is a pic of the setup.

	Quote: Originally Posted by rwedel
	Just a question, Where is your Ignition located ? Is your spark plug wire (s) touching the muffler (s) ? Even if it is 2.4, their is still potential problems that can occur.

[rwedel]

It doesn't appear to be a setup issue.

By chance, do you have another receiver, I realize that a 7000 should be all that's needed however a
a 9000 or 9100 would be better since they have 2 satellite receivers instead of one.

I believe that trying a different receiver is the ticket.

What do you all think ?

[MikeC3D]

I had the same scenario happen to me a few years ago with a DA 50, it just happened to be the ignition wire going to the plug that was transmitting RF interference, I guess the shield wasnt doing its job, and was fairly new, less than one year old. After that, never had a problem with it that wasnt my fault. It was a pain to figure out, cause we swapped every single electronic part out in the plane one by one, and the ignition was the very last piece we tried, wouldnt you know it...lol

[Barn-E-Stormer]

Have you ever damaged the TX antenna? Maybe shut it up in the case and popped the end cap off? My TX antenna problem first showed up as elevator glitching.

[bill hatcher]

We had the same type of problem with the Prototype P-40. In the end after all extentions were replaced, Batteries moved and a host of other items We found the spark plug had a crack in it. Changed the plug and the problem was gone. Don't know if this is your problem. Just another thing to check. This was on 2.4 by the way.

[bodywerks]

Look at your elevator servo extensions, particularly all connections. That could be a source of the porblem, but the first thing I would do is change out your spark plugs.