When ignitions fail, do they usually just quit producing spark or so they start producing weak spark leading to total failure?
My blue label Falkon seems to have a weak spark, not a bright blue spark like it should be. This was in the sunlight though, but shade was provided by my hand. Engine has been getting harder to start over the last several flying sessions. I had one flight today and it ran good during the flight. Couldn't get it restarted for a second flight. That's when I checked the spark. It's getting plenty of fuel, so that's ruled out. Went ahead and popped in a new set of plugs and still couldn't get it to pop. I put a new set in the last time I was out too.

I think they generally work or don't but in electronics, any thing can happen so I'd not argue there couldn't be degradation. My cases of failure have been total. If you just put in new plugs, then one or both boots may not have been seated well, which can crater an ignition easily and quickly.

The boots lock on with set screws.

We just had one fail so to speak. It still worked, but would cut out at high rpm. Tried to tune it out and could not. We changed out the ignition with a spare one I had and the problem went away....

What's weird is that it would run great and not miss at all. That is if you could get it started.

I have had several ignitions fail and always the failure was intermittent. One failure was that on hot days after more than 10 minutes into the flight, the spark would quit on one cylinder (on a twin engine). Let it cool off for 20 minutes and then it was fine again. Another unit failed completely, but only on one side. I could swap the two ignition wires and see that the engine was running on the other cylinder (one cylinder cold and one hot).

One failure was such that the ignition was putting out so much RF noise that the throttle servo went crazy. The engine was running OK (spark was OK) but the throttle was surging back and forth. I thought it was a bad servo so replaced it. Same thing. A third servo yielded the same result. Replacing the ignition solved the problem.

When it happens, does the rpm stays at the middle range, even though the throttle advanced to full?

My engine starts to behave like that and I wonder if the ignition module is bad.

Smoke is what makes them work

When the smoke all gets out, they do not work anymore

nonstop it would still go to full throttle, just that it would start missing.

Try a prop that presents more of a load to the engine. If the ignition module has a rev limiter feature programmed in, it could be that your engine is revving past the preset point and is turning off when over a certain rpm. Some of the ignition systems sold by RCS utilized that feature and could be reprogrammed to stop the automatic limiting.


Ed Cregger

Does anyone ever consider checking the condition of their ignition batteries when ignitions act weak? That spark has to come from somewhere and without a battery, guess what?

Ed/Pat in our case it was the ignition. We had already done the battery, switch, etc., etc. The igniton was the last thing we checked and it was the source of the problem.

I've had two ignition problems in my short time running gas engines for R/C. My first problem last season was identical to DMcQuinn's second problem, though in my case it was due to the threaded on tip on the top of a new NGK not being tightened properly, I know now that they have to be tightened out of the box[:-] .
More recently, I had gotten my Yak 54 ready for the season and ran it up at home, no problem. When I got it out to the field it would want to start, but would die within the first second of starting at idle. Bottom line the cheapy XYZ (blue plastic module) was toast. I replaced it with a new RCExcell and also bought the RCExcell ignition tester that drives the ignition module without running the engine. It seems like a must have when troubleshooting an ignition problem[8D]
Pete

Battery is fine. Just charged it before the gig. I have a 4 cell nicad I'll plug in before I test another ignition though. That'll be easier than swapping out ignitions.

Standard answers we get about batteries when we ask "its a new battery" DID YOU TEST IT?', its a new battery and I just charged it. DID YOU TEST IT??"
There are many failure modes on batteries so PLEASE when your having ignition problems TEST THE BATTERY

With a load tester [X(]

Another thing to check is the silicon boot in the plug cap. This will crack with time, and let a spark find it's way to the metal cap. I've had this happen. A new boot and some dielectric grease fixed it. I have also had ignition module failure. My experience has been that it will let the engine fire, but will not advance. I appears to be a fuel problem (running on prime only), but is is really ignition failure.

battery load tests fine. There is no silicone boot in these caps that I can see. Just a spring that contacts the end of the sparkplug. Just got back into town. Hopefully it will cool down before dark so I can try the other ignition out. I was talking with my flying buddy and he reminded me that the last time out it was starting only on one cylinder and then both would finally light.

I recently replaced the stock ignition of my MLD28 with an RCEXL and at first was having all kinds of problems starting the engine. I tried 2 different 4.8 battery packs, bypassed the switch, etc. and nothing seemed to work. Then I tried a 6V pack and it seemed to work much better, but still I noticed the spark was intermittent. I know this ignition is supposed to work with 4.8 so I decided that maybe the module was bad and made arrangements to return it. Then I decided to try the RCEXL ignition with the original (MLD) hall sensor and guess what, it works with no issues. It may not happen too often, but hall sensors too can go bad or become intermittent.

I have the newer gold ignition module on a 80J, it seems to be failing much like yours. After 10 minute flight the engine just quits, I burned 5 gallons of 32 to 1 break-in mix and was in the process of switching to 40 to 1 fuel when the problem began, the engine is new while I've owned it for several years. Was purchased from RCS before they closed their doors. I'm using the Epower switch. I did a wiggle test on the wiring with engine on and found no problem. The battery is a 6 volt 1650 NiMh that tested at 6.5 volts with a 1 amp load following a deadstick landing. I decided to replace the switch but discovered Epower is no more. I find that odd because Michal Janousek was the point of contact for both Epower and ZDZ engines.
I bought a Cermark switch to try but decided to replace both the switch and ignition. I'm installing an Rcexl unit rather than mess around with another ZDZ ignition. I own three 80's, 1 RV and 2 J's, each one has a different ignition module? I guess they never got it right! With the current price at $499, I can only wonder how much longer ZDZ will be around. To be honest, I think it's a very good buy at $499.

Let me know how you time it with the RCExcel. I know they are a little bit different. You gotta wonder about the pricing.

It will be set at 28 BTDC. I found that the ZDZ module was set at 6 BTDC when following the instructions, I had ask RCS what the timing should be set in degrees and was told to set it to the dimension in the instructions, however in my case the instructions were revised. I can remember 6mm, 6.5mm and 7mm, pick one. I found that 6 BTDC worked fine although the engines do bite back once in a while..
I plan to fly the plane on Sunday and get a good base line rpm, change the ignition next week and compare. I'll results and photos. I expect the everything to go without a hitch, time will tell.

I've read the RCEXL was 28 degrees, wasn't sure what ZDZ's was. Did you use the original magnet in the hub and just move the hall sensor?

Here is what you were trying to remember regarding the ZDZ ignition timing:

Measure A
40 RV-L - 6 mm
60 RV - 6,5 mm
80 RV - 6,5 mm
80RV-J - 7 mm
80 B2RV – 6,5 mm
100B2NG - 6,5 mm
120/160B2RV – 7 mm
160B2RV-J - 7 mm
210B2RV – 9 mm

I've got the picture to go with this, but the uploaders are misbehaving for me....give me a bit and I will get it posted.

Put the replacement igntion on, (didn't remove the old one). I checked the old ignition first (spark) along with load testing the battery. Went to flipping the prop and nothing. I'm like "what is going on here". I checked the battery again and it's at zero volts. I flip my ignition cutoff switch back and forth and nothing. I have a sevo hooked to a toggle switch that kills the igntion battery's power. I usually run a choke servo, but it was hard to fit in this plane. I left the switch in the "on" position and went into the EPA on that channel. I increased it and right away had voltage. I was watching the meter while increasing the EPA. Strange that occured because you could hear the toggle switch "clicking" into the on postition. She fired up right after that. I warmed her up for a minute and shut it down. It would start on the first flip ten times in a row. Problem solved. Thanks guys for the help!