I second Karol's advice, those guys know their stuff about CDI.

When 2.4 came out a few years back I was and still am flying my 1/3 cub on 72 meg, I frequently had glitches, not bad ones but still they were concerning. I and some other folks attributed them to all the flying wires on the float rigging. I was told about the 2.4 eliminating any engine or metel to metal interference, so I bought a futaba 2.4 and never a glitch again. The only problem Ive ever had is when I put the ignition to close to a throttle servo on a 50cc yak and it raised hell with the servo. We used to put chokes on long servo leads back in the 80's to avoid interference, but honestly I dont even worry about it anymore

Peter,

A couple of things: first, I tried running an FM radio on 72 MHz on a gasoline powered truck that has a 26cc magneto ignition engine. I had the same sysmptoms you described...radio worked great until I started the engine, then everything would go haywire. I changed the tx and rx to 2.4 and problem was solved. Nothing generates more RF noise than an old style magneto ignition, and the proximity of components in a RC truck makes radio requirements much more demanding than in an airplane. I seriously doubt the problem is in the radio

Your specific description brought to mind a recent event in my airplane set-up, also on 2.4 Gig. The engine is a 30cc gasoline engine with RcExcl CDI unit. I was running a separate batteries for ignition and radio. The ignition battery was a 2 cell Li-ion and the radio a typical NiMH. Everything would work great as long as the engine was down. Soon as I started the engine everything would go haywire.

I traced the problem to a faulty ignition battery. Even when "fully charged", this battery was old and had developed so much internal resistance that the CDI unit would drop voltage below a usable range for the CDI (around 4 volts).

Take another look at your batteries and use fresh on the ignition.

MattK

If you are running an rcxell ignition double check by looking into the plug cap and making sure you can see the end of the resistor protruding into the open area in the top of the cap. I had one slide out which cause all kinds of glitching and engine mis.

Thanks for all of the input guys,
I have bought an rcexl unit and will install and test tomorrow. The problem was occuring on an Evolution engine with the ignition unit that evolution supply, not the rcexl type.

MTK, I forgot to mention that I swapped out the batteries as well, just in case. No difference.

I will post back if the problem has been solved with the new unit. Fingers and toes crossed.

Cheers,

Peter

The mystery of the 2.4 radio interference problem (well mine anyway) is solved! I tried a champion brand plug, and fail. I bought one of those E6 plugs from Home Depot, you know the ones that are direct replacements for many different plug types including the NGK BPMR6F plug (the one recommended for my engine). I tried this new plug and bam! MY RADIO STILL FAILED EVEN WORSE!!! I finally said to myself; dang it self, just suck it up, order the NGK BPMR6F plug from www.sparkplugs.com , pay the $10.00 shipping and try it. So I listened to myself. The plug arrived: I installed it: I tried it: And BAM! IT WORKS LIKE A CHAMP!!! Not one glitch, not one radio lock up, just one SWEEEEEEEET! running engine! Goes to prove; just use what the book calls for and you can't go wrong.

Surely you have one of the major auto parts chain stores somewhere near you, you can get genuine NGK plugs from one of them for about $3 and not pay shipping, they will probably have to order it and it might take a couple of days, but you still won't get stuck paying for shipping! I ordered NGK plugs from Auto Zone and had them 2 days later for around $3 or $4 each.

The NGK BPMR6F has a number of "1270" when you go to order one at the counter at Advance Auto parts et al

I tried to order the NGK plugs from both Auto Zone and O' Riely's. Both places said they could not get them. Ned time I need one I'll be a bit more persistent.

Have you tried Advance Auto parts? I plan to tomorrow.