flapwad

I have a brand new DLE 20 RA engine installed in a 80" PT-19 that is acting very strange. I have over 2 dozen other gas planes, so am not a newby to gas engines, but this is my first DLE and I've never seen this behavior before. All my other engines are the "cheap ripoff versions", e.g. RCG, RCGF, EME, AGM, etc. and I've had no problems with any of them.

The engine will start at the factory needle settings of 1.5L and 1.5H and has a beautiful stable idle, but will not run steady above idle at any needle settings. As the video shows, when the throttle is advanced from idle, the engine will start a continuous cycle of revving and bogging, and no changes in high or low needle settings will have any effect on it. Tried every combination of needle settings and I can make it slightly worse, but not better. Changing needle settings has almost no effect on starting, idle, or the odd high throttle behavior. Tried replacing the DLE plug with an NGK, no change. I tried running with the cowl off so I could see if there was air being drawn into the fuel line (none), made sure the plug cap was fully snapped on the plug. Other planes run on the same fuel with no problem, so it's not the fuel. Checked the fuel system for possible air leaks and good venting and everything looks good. I am going to pull the engine and run it on the test stand to eliminate all the switches and optical cutoff as possible problems. Beyond that, looks like I'll have to take apart the carb and check for problems there.


Any ideas? All my cheap(er) Chinese engines run great, my first experience with DLE is not encouraging.

http://www.youtube.com/watch?v=mUPL7SNlals

mrbigg

My Feedback: (21)

Unhook the optical cutoff. They've been known to cause problems.

flapwad

Thanks for the tip,

I have it on the test stand now, will try it with no optical cutoff and see how it behaves. It is also very hard to start, basically impossible to start by hand flipping, need to use a starter. Sure idles nice though.

Truckracer

My Feedback: (19)

While I usually try to work through problems myself, if that engine were mine, I think I'd be sending it back for warranty repair or replacement.

I own several DLE engines and all perform very well, as do others in the area. Sounds like you got a lemon.

3136

If it's impossible to start by hand it's usually too lean on the low, but you said it transitioned well so maybe not.
Mr Bigg probably has the solution, if that's not it try an ignition from another one of your engines. also look at the gas engine sticky there is a test you can do that will indicate what is wrong, (if anything)
Apart from that I would send it back.

bcchi

Sounds like you do not have the plug cap all the way on.I have a new DL 20 RA The plug cap is a monster to get on correctly ,snap ring must be all the way past the hex on the spark plug when it is on right.
If you have the 45 degree cap which is what they come with it is nearly imposible to get on.Put some silicone lube on the plug and in the boot ,not too much.I some times champher the hex on the spark plug a litttle with a dremmel sanding drum.If this is not the problem maybe Hall sensor(pulse switch).Some times hall sensor has backed out of the mounting bracket a little.Like told bypass the kill switch and batt switch first and try that.It is a spark problem ,I think.But what do I no.My new DL20RA is a little monster runs great,have it in a aero Works profile.Have 12 DLE engines all run great.
Sorry about spelling to tired to spell check,past bedtime.
BCCHI AMA 2500

flapwad

Bcchi,

Yeah, the plug cap not being seated was the first thing I thought of too, had that problem before. There's a possibility that it's not all the way seated but when I push it on, it goes all the way until the plug cap bottoms out against the cylinder head, then springs back about 1/8" so there's a gap between the head and the edge of the cap and part of the hex is showing. On all my other engines the hex is fully hidden by the cap but there's no way to push it on further since it's bottoming out on the head. On this one, there's no definitive "snap" when the cap seats like on my other engines. I'll try pushing it on with the spark plug out of the engine and see if goes further. If that's the problem, don't know what I can to to fix it. Tried it with the spring in and with it removed.

I agree, it sure seems like a spark problem. I took the carb apart and can't see anything wrong there. Nothing obviously wrong with the Hall sensor. Could just be a bad ignition box.

Scott

Truckracer

My Feedback: (19)

If pushed on correctly, like on all other DLE engines / Rcexl ignitions, the cap will just cover the hex part of the plug. If pushed on so far that it bottoms out against the cylinder, you may have cut through / damaged the silicone insulator in the cap.

flapwad

Update: spent all last evening trying to get the engine to run on the test stand with no luck. Test setup had no electronics, just the engine, battery, 5.5 volt regulator, and fuel tank. Manual throttle and choke. Could not get it to run, although it would pop and sputter and nearly start on every flip. Interestingly, it will almost start only if the throttle is fully closed, if I open it even slightly, it won't pop at all. It's definitely getting spark and fuel, but acts like the spark is very anemic. Too much fuel in the cylinder seems to drown the spark.


I'm going to pull the ignition out of another plane tonight and see if it acts differently with an ignition swap. I did pull the needles and check them, they look fine and no contamination in the carb.


At least I know it's not the opto cutoff, switches, or fuel plumbing in the plane.

av8tor1977

My Feedback: (6)

I agree it sounds like ignition. But after changing ignitions and sensors to check, I'd be looking at the reed valves too.

AV8TOR

flapwad

Problem solved. Took the ignition off an RCG26 and hooked up to the balky DLE20 and it started on the first flip and ran like a screaming demon.

av8tor1977

My Feedback: (6)

Cool. Glad you got it figured out!

AV8TOR