Looking for suggestions.

I have a quarter scale Edge 540 with a CRRC 26cc gasser on board. Spark plug cap on fully, covering the plug. Although it seems to slip on kinda easy.

Throttle linkage is nyrod inner and outer from engine to servo. Throttle servo in back of wing tube. 16" from ignition.

Futaba 2.4 Ghz 7 channel receiver. Ignition plugged into smart fly optic kill switch, then gear channel.

I have no problems with the engine off and all surfaces move and return to nuetral fine.

With the engine running, I have problems when throttling up, the throttle will surge and the elevator will move up without input on my part.

I have the ignition battery in the motor box, approx. 15 inches from the receiver. Receiver battery back by receiver.

That was the first set up.

I recently purchased a WIKE IBEC from TBM and installed it last evening. So now I have the same setup with no ignition battery. I installed a ferrite ring on the receiver wire from the IBEC to the receiver just cause I had a few laying around and I noticed that the 42% Zues had them installed on their IBE. Everything else in the set up is the same.

The IBEC is plugged into the gear channel, gear channel set to +100 and -100 end points. Zero trim.

Same as above no problems with engine off.

The engine runs well with no cut outs or stoppage.

Same problems as above with the engine running. Elevator moves on its own and throttle surges without input.

I have a WIKE IBEC in my 100cc Yak with a DLE 111cc without issues.

After rereading this a couple of times, I'm thinking my spark plug cap may not be tight enough. It doesn't rattle but is not as firm as my other engines. The metal ring is around the base of the cap.

Is it possible that could be the cause of interference?

Can I put a clamp around it to tighten it to the plug?

Thanks in advance for any advice/suggestions.

Bill

Put a thin hose clamp around the base of the cap

The plug cap is the problem. As you noted the cap fits a little loose, the engine causes it to vibrate and the ground path arcs between the metal plug cap housing and the hex of the plug causing the RFI. Use a small screw type hose clamp on the area where the cap locks on to the spark plug's hex section to tighten the connection

Thanks W8ye and Jody, I appreciate your quick response.

I will get a clamp this morning and try it.

Bill

Sounds exactly like RFI to me. It's probably the cap, as already suggested.

If that don't fix it........... Is the elevator servo new? What about the servo extension going from the RX to the elevator servo?

I once had a Y harness go bad on a glow plane. It acted just like RFI. Was causing the ailerons to jump around randomly when the engine was on.

Just an idea, but I'll bet the hose clamp on the cap fixes it.

Yea, we have a fix!

The .99 hose clamp did it.

Thanks guys.

Bill

As Jody and bill says,probably the plug cap make sure the cap is going all the way down. When any of the RCEXL caps are on properly the wire snap ring must be all the way past the hex of the spark plug.They do not go easy and come off even harder. We seem to get more RFI complaints on 2.4 then we got on 72.I think the reason for this is back then a lot of fliers were using just the rubber boot and a resistor spark plug this was nearly always OK. Now many of the fliers are using the RCEXL cap or somthing about like it.We find nearly all RFI compliants now are caused by cap not being on all the way or wrong cap on wrong spark plug. You could not believe some of the things we see of fliers trying to use the wrong combination of spark plug and cap.Like 5/8 cap on 3/4 plug 3/4 cap on 5/8 plug.5/8 hex on CM6-10MM plug just trim the cap down a little.Will not work they have to be right.The small hose clamp is a good Idea.We always used a hose on the Bosch plug covers,kinda ugly but works. Use a fuel line clamp only 5/16 wide not 1/2 inch.We have instruction on our web site on how to get the RCEXL cap off with out using pry bars,vice grips or dinamite. O yes they do.
BCCHI

BCCHI..

Can the troublesome RCEXL metal plug caps be changed to a rubber plug cap/connector and a resistor spark plug? (With the braided shield connected to an engine ground like on the original CH units.)

AV8TOR

On the 5/8 and 3/4 hex caps for the regular sized resistor plugs all you would need to do is remove the metal cap housing, separate the braided sheilding, twist it together, crimp a lug on it, and connect it to the engine, done. I wouldn't trust that on the current CM-6 style caps without coming up with a more positive method to hold the silicone boot onto the high tension lead, could be done though.

The cap is not the problem...
Lack of knowledge is...
The RC EXL cap used with the proper size spark plug is as good as it gets...
If it was a problem there wouldn't be over 30,000 DA and 3W engines flying around with the same type cap....

Read the original post Ralph, it's not an Rcexl ignition, if it were this thread wouldn't exist. I should have mentioned that in my reply to av8or, the Rcexl caps don't have this propblem, it's just some of the cheaper Chinese ignitions like the CRRC that have the problem.

Ok, thanks, but I like the idea of having an ignition system that I can move around to different engines/spark plugs. Can one change the cap to a rubber style and use it on a resistor plug, or is the resistor that is in the original RCEXL ignition unit caps necessary?

AV8TOR

Rcexl only puts the resistor in the plug cap for the CM-6 spark plug. There is no positive connection that holds the high tension lead into the silicone boot. The full size plugs use a coiled spring that fits over the end of the plug, the other end of the coiled spring has two spikes that go through the high tension lead, when the cap is on the plug there is no way it can come apart. The picture is of a CM-6 type cap, you can see the resistor, it can be pulled out fairly easily, the clamp on the wire side of the cap holds everything tightlytogether. If you used the Rcexl ignition withtheplug cap for the 5/8 hex plug and substituted the NGK CMR6A plug for the CM-6, and removed the metal housing, you would have an ignition that would work on everthing but the 1/4-32 plugs.

Try this at your own risk, personaly I like the positive connection of the metal caps, I dont ever worry about my plug cap coming off. Also, although the CMR6A type plug is a resistor plug it also has about 1.5mm longer reach into the cylinder, don't know of any engines that would have a problem with that but there could be some out there.

Exactly the info I was looking for! Thanks!

AV8TOR

Yes you can run just the rubber boot.This is usually fine when you can run a resistor spark plug.I would not do it on the CM6 -10MM plug as it is not a resistor plug
We have requests to change to just the boot or fliers want a system with the rubber boot. I believe this is because they are having problems with the metal cap.
I have been reworking the RCEXL caps and putting a clamp on them,use a 5/16 wide fuel line clamp.You can relax the snap ring or leave it off.Cap then goes on and off easy.
I have a RF meter it is suprising how much RFI is ruduced just by using a resistor spark plug.
There is a resistor plug that will work in place of the CM-6 a NGK-CMR7A.It is a 5/8 hex plug with a little longer thread. You can use two gaskets on it ,I don't.
As -Jody says you would not want to use the rubber boot and terminal that comes with the RCEXL cap.for the CM 6.I have boots and terminals.
BCCHI

OK- My bad,I did not look back and see it was not a RCEXL cap. Grumpy -They do have problems with the RCEXL cap. You no some people can tear up a anvil.
Must be a late am tired,tired.Gone Gone.
Grumpy no two