ORIGINAL: alexedit
It's al older OS 61 SF -
I feel weird leaving the plug in when I put the engine at full speed because it doesn't smoke as it should. But then when I take it out (at open throttle) the smokes starts coming out of the muffler as it should. does leaving the glow stick on the plug for a few extra seconds while you are fiddling with the engine running damages the engine?
It won't do the engine any harm at all to leave the glow running, but running an engine with a powered glow at high revs will cause the plug to burn out quickly so it's not advised, if only for your wallet's sake. It can also mask mixture problems if you're trying to get things set up - a powered glow plug will burn a richer mixture happily that will flood an unpowered plug.
There's three reasons why removing the glow driver will snuff an engine - first; if the engine's so cold that the catalytic conversion won't happen (it only takes 10-30 seconds to warm up though), second; if the platinum on the coil's worn off to the degree that it won't support the reaction (get a new plug), or third; if the mixture (typically the low speed mixture) is so rich that it's flooding the plug and cooling it off. If it's the third case tune the engine correctly and if it still happens you can get glow plugs with "idle bars" which stop the plug being splashed - HOWEVER make sure you tune it right first. Using an idle bar instead of learning to tune an engine is a band-aid solution and is only masking the problem instead of fixing it.
The other thing to check is your fuel - too little OR too much nitro can cause all sorts of problems, as can fuel that's absorbed water through exposure to humidity. When I started I had a bunch of problems with my Super Tigre engine idling till I a: learned to tune properly, b: got help from people at my club trying out different borrowed plugs and fuels mixes.