3W 150 giving me trouble - ignition?

[AHP]

I have a 3W 150 TOC with the older blue dot ignition. The engine has never given me a bit of trouble until recently. After a few flights the engine will start to cut out and act almost like it's too lean. If I bring it back to idle quickly it will usually spring back to life long enough for me to bring it down safely. Once it starts acting up, it starts to run erratically, fading in and out at anything over about 1/3 throttle. The first few times it happened it was after several flights so I thought my ignition battery was getting tired. Each time this has happened it's always been after a few flights. I swapped out the ignition battery (was a 3300MAH NIMH) for a Fromeco 2-cell 2400 with the regulator set to 5.2v (same setup I run on all of my other gassers). While I had the cowl off I cleaned out the carb screen and went over everything with no apparent issues. Today on the first flight the engine ran flawlessly. On the 2nd flight after a few minutes it started acting up again and nearly deadsticked on me. The problem is getting worse and more and more frequent as I used to get a few flights out of it before it would act up. Could this be the ignition? I'm very hesitant to say it's tuning or the engine is overheating because it runs like a champ for at least a few flights (well.. used to) until it starts cutting out. Deadsticking my 40% Cap is not my idea of fun. Any suggestions would be greatly appreciated.

For what it's worth, the engine is well-baffled, I'm running Amsoil at 50:1 and turning a PT 32x10 prop.

[Tailchaser]

It looks like most shops are closed until Jan. 2nd. I would hate to see you crack up a plane because of a dead stick.
Have a feeling it's ignition related, but I would check your regulator out put also might knock down the voltage when it gets warm,.......it's happened.
But if I had to guess I would either borrow another ignition to try that out, or wait and send it in to a 3W dealer to check the ignition that might be going south.

Chuck

[Dr. Yankem]

It's possible its the module... When you say fading in and out do you mean running on 1 cylinder not 2. That would most likely be the module.
But if fading in and out refers to carburation then check:
1. High end needle might just be too lean. After first flight when engine is hot the leaness becomes more evident
2. Screen dirty...but you checked that already
3. Tank plumbing problem (usually clunk not hanging free)
4. Possible faulty throttle servo or loose servo mount causing butterfly in carb to occilate.
To really eliminate the module, try borrowing one from someone and swapping it out.
Jerry

[xtdsm]

it sounds like it's overheating. what kindda temps are you getting right after landing?


Ahmed

[AHP]

Fuel plumbing and throttle servo are fine. The engine was actually a little richer today then usual, most likely because of all the crap I cleaned out of the screen. I hightly doubt the engine is going lean and or overheating. Up until today, I could get several flights out of it before it would act up which is way I initially attributed it to the ignition pack. Today, with a fresh battery and regulator, cleaned screen and slightly richer mixture I got one perfect flight and the 2nd one was cut short by the issue. Some of the symptoms are indeed indicative of running lean but but the circumstances don't really jive. The engine will run perfectly and then sag and almost cut out with no prior indication. Usually, if I pull back on the throttle when I hear it cut out it will run normally again and I can advance the throttle. Also, it's begun when I'm at around half throttle and just cruising. I've never temp'd the engine (or any of my engines) but appears to be the same temp as usual - which is rather cool compared to some of my engines. If it was going to overheat, it would have happened in my first flight during some extended hovering/harriering and full throttle smokey blast offs - the engine ran flawlessly, though. The 2nd run I was flying conservatively when it started. I've seen engines overheat, sag and then die in the air and usually you've got an indication as to what's happening. This is pretty much instant whenever it happens. I do need to check the plugs and the gap but I don't think that's where the issue lies. I appreciate the input, fellas; keep it coming.

[Michael Glavin]

Maybe an air leak, check the phenolic carb spacer between the carb and crankcase. As the engine warms up things GROW!

[Supermod56]

Swap the Ignition, they will do that when they get hot. The 3W ignition requires air to flow under it to keep it cool, needs to be on some sort of stand-off, I run about 3/16" gap under mine.

Tom

[Michael Glavin]

Since the engine has ran fine as rigged for some time, It seems unlikely the ignition is heating up now. Especially considering the cool weather of late, but you never know! That said isn't or was'nt the heating problem an issue with a batch of later model ignitons with the bells and whistles?

[JeremyHolt]

My father has the same exact engine I had the same exact problem. You could fly for a couple a minutes and then sounds like it starts running on one cylinder. He did have a fuel leak from an old gasket on the cylinder which we fixed but the problem persisted. Come to find out bad ignition. I would try to maybe borrow one from some one else and switch it out. I bet that is the problem.

[AHP]

Come to think of it.. The ignition model is zip tied to the top of the engine box with a piece of foam underneath it. A month or so ago I replaced the zip ties and strapped the module down a bit firmer than it was before. I'll try standing the module off to give it some clearance underneath. I'll give that a whirl and see how it goes.

[Supermod56]

Do that, you MUST have airflow underneath the box, I usually use 1/2" weatherstrip down each side and bolt it down with 6-32 screws and ny-lock's the center holes in the box, gives me some padding and airflow. Also, this applies to the old ignitions as well as the new ones

Tom

[Plane Wrappers]

This is my first 3W ( 157 Competition series ) I strayed away from DA on this one.
I heard about this problem earlier. does this mounting look OK for good air flow?
I have 1/4" under the module.

[Bunky F. Knuckle]

Monty, gap looks good.

AHP, for what it is worth, have you reverted back to the NiMH pack that was installed prior to you installing a LiON with reg.???? Get a little bit under the ign. module, and try the NiMH pack as well. Let us know what you find.

Bunk~

[Supermod56]

	Quote: Originally Posted by Plane Wrappers
	This is my first 3W ( 157 Competition series ) I strayed away from DA on this one. I heard about this problem earlier. does this mounting look OK for good air flow? I have 1/4" under the module. Attachment 31014

That'll work
Tom

[AHP]

I'm in the process of making a mount almost identical to Plane Wrappers. I should be able to test it today if the rain holds off. The module definitely overheated badly. One of the zip ties around the mounting tab was starting to melt. Hopefully it's not fried..

Bunky - I haven't tried the NiMH pack again. That pack is pretty much shot anyway.

Does anyone know if higher voltage to the module will create excessive heat? Would it run cooler if I bump the regulatar all the way down to 4.8v? It's currently set at 5.2v.