Hi

I know this has been a common problem with this engine, but, anyone know how to fix the interference produced by the spark cub ??

Thanks

Fernando

Fernando,

Double check that all ignition grounds are in place and that you have a resistor spark plug.

I fly an RCS 140 with NO igniion interference. I will say though that I have NOT had good luck with any ignition engine and a straight FM receiver. I use Futaba PCM recievers in all my gas airplanes with no problems. You may also want to have your receiver checked. I bought a used Futaba PCM receiver and it would not range check with the engine running, sent it to Radio South and they performed their magic and now it range checks at about 150 feet.

In summary I would suspect that this is NOT an engine problem as such, but something else may be going on.

Good Luck

Jerry

I saw a like with this interference and it was found that the ground to the ignition module was bad. When it was improved, the noise was eliminated.

Hi All,

There is another thread in this forum which talks about the grounds breaking where the ignition shield is soldered to the PC board. They use two loops of wire to hold the shield and ground it to the PC board, there apparently have been some problems in this area so that is definetly worth checking.

Jerry

Check out my ignition grounding post below yours. It was me that was flying my RCS 140 with a FM(non pcm) receiver and had a broken ground connection at the point where the plug wire enters the ignition module circuit board. Those two teeny little loops of wire soldered around the HV shield, and circuit board ground plain, are the only ground source for the HV shield, plug cap, and the engine itself. My JR did good I kept getting little hits, but nothing bad happened. This all happened after only one tank of fuel run on the ground, I was flying on the second tank, the engine was running very good. If that ground connection opens up, you will get sparking at the plugs gap(like you should), plus the broken ground connection will be sparking to complete the ignition circuit return to ground. Only because its high voltage does this work. Unbelievably, the engine continues to run like there is no problem. I fear that if I had been using a PCM receiver, the problem would have gone unnoticed untill failsafe kicked in

I fixed mine by resoldering heavier loops of wire around the HV shield wire on the circuit board, and also added another separate ground wire from the circuit board ground plain, to the black wire that is grounded to the shield at the plug cap(the wire you are also suppose to ground to the engine frame). So I now have a backup ground, in case one fails. You should also make sure the plug cap fits on the spark plug firmly. If its loose, it could also be a noise source. RCS suggests a hose clamp around the cap, to hold it on the plug tightly. Another suspect point could be the crimp on pins that connect the ignition to the battery, they sould be soldered. I also added a strain relief to the HV plug wire befor it enters the ignition module.

Another interesting thing, is that I was getting a on the ground range check of around 200 feet, with the antenna down, and engine running. Only in the air did I get the interfierence. Apparently the ground(as we walk on) was absorbing the noise because of its close proximity to the source.

Now that I found the problem, my FM(non PCM) radio link is working flawlessly with this engine.

By the way, there is no resistor plug available in this size.

Hope all of this makes some sence.

Kevin

I installed a hose clamp on the spark plug shield on my RCS 1.4 gas engine. The shield was not tight on the plug base but still very hard to remove. I had noticed some servo jitter and could move the shield easily on the spark plug. After installing the clamp, no more RF interferances.
Evert

Thanks for all your replys, I will fix the pc board.

Regards

Fernando

I also am expeiriencing noise interference with my rcs 1.4. I would like to note that the sheildings path to ground is not only at the circiut board, but also at the spark plug cap. the outer metal shell of the cap directly connects to the outer portion of the spark plugs wrench flats, which ground to the engine. you can prove this with a resistance check on a meter.
I am finding evidence of arcing from the inner high tension lead at the spark plug to the outer metal sheild cap of the spark plug boot. Electricity always takes the least path of resistance. the planned path should be accross the electrode. but if it can find an easier way like the sheild, it will take it.
does the hose clamp trick really do it? Or is there a better fix? like a different style boot?

Rick,

I would guess that if you are seeing arcing inside the cap, then your cap is defective. No amount of improving grounds is going to solve this, it sounds like insulation breakdown.

My 2 cents

Jerry

I think you may be right. So far it looks like the lack of a good contact wear the boots inner High tension conector grips the terminal of the spark plug. A little loosenes hear an the electrons head for the easier route. I am plying around with it and have found that the boot may seem conected, but not realy on the inner connection.
It just seems that a hose clamp on the outer shell would only improve the sheilding capability, but not the source of the problem.
I'll check into it some more.

The hose clamp thing did nothing for me, it didn't really seem to tighten anything.
I replaced the plug cap and now have a nice tight fit, like when it was new.

Jemo!
Were did you get the replacement cap? From rcs? or something else, or better?

I got it from RCS , $10.00. I don't know if any of them are better or not.
Maybe Ralph or Terry can tell us.

Great. What did they send you? The whole lead from the module? Or just the cap? And how was it to replace?

Just the cap, cut the black heat shrink off and unscrew the cap.
When you install the new one, get some heat shrink or tape you will see why it is needed.

what all props are you all running on your RCS 1.4 i am running a 18 x 6 mejzlik?

http://www.krayzc.netfirms.com

Currently APC 18X6. I am still working bugs out of the A/C, and havent refined to the best prop.

correction, I mean APC 16X8, I think I will try a 17X8.

Bye the way, I solved my range problem. It was infact a loose spark plug cap. I got it off and cleaned up, and made sure it went back on in a positive way. Every things fine now.

You need that hose clamp on the spark plug cap.
My RCS 44B2 came with hose clamps and I removed them thinking they were to prevent the cap from coming off. The caps seemed tight enough for me.
After about ten flights, I started to get glitches. I changed everything- RX,TX, batteries and frequency channels. Nothing worked. By this time I could not get 1/2 the off engine range. Finally it dawned on me that RCS had supplied those hose clamps for another reason than keeping the caps on. So I reinstalled them and the problem went away.
The 44B2 is two 140's made into a twin.

I just lost a plane because of the RCS 140. After one flight, the cap started to arc. RC Showcase replaced the Ignition, after another flight or two, the same problem developed, and worsened. The motor began throwing backfireing, and throwing props. The motor would run fine one minute and the next it would stop running as if the Ignition was turned off. By the way, Jerry is not well informed. C&H Ignitions has a billet aluminum cap that fits firmly, and uses a hose clamp. I have them on one of my other engines, they are great. I only wish that I had sent the ignition to them before this. Dan

so what is the deal do we need to send out the int. to have the standard cap changed?

You do not have to send the unit to C&H, if you can solder.You can order the caps and leads by calling 307-857-6897, ask for the Billet Aluminum Caps. The guys at C&H know more about electronic ignition modules than any of the new commers in this business.

thanks for the scoop so it just a matter of soldering the new one on there

A DA or 3W cap will also work and need no hose clamp..They fit so tightly that it takes a screwdriver to lever the cap off the plug...RCS should take some lessons.....If you take the cheap shielding off the RCS cap you will see what I mean....Been there....