Basic engine tuning.

[49dimes]

O Tay!...

 

[AsphaltPilot]

Actually it would be nice for the FOG talk to clear up so people that are reading about tuning don't have two pages of FOG talk.

Thank You I'm trying to learn something here..

 

[N-O-V8-R]

Ok Terry maybe you can help me out with this one. I'm usually pretty good at getting my engines tuned but this one has got me stumped.

It is also a DLE 120, On the low end it loads up and if I try to clear it, it stumbles and quits but if I jab the throttle it acts lean and dies instantly.

On the High end it act lean, if I go wide open for a few seconds and bring it to idle it stays at a high idle for almost a minute then loads up slows way down and quits. If I even let it start to load up, the instant I give it throttle it dies whether I do it slowly or nail it.

One more weird thing it did, I was straddling it to hold it back and I took a step forward and the plane lunged a bit. When the stabs hit the back of my legs and the plane stopped the engine stumbled to the point it almost quit.

I've always done it the way you describe and start on the low end, but I can't seem to get a reliable idle to start with and I know that has to be what is throwing off the high adjustments.

I had the idea to just get everything rich and then just slowly lean it back, but just wondering if you had any different ideas. I know it's difficult to diagnose engine issues through a keyboard but thought I'd ask lol

did you recently rebuild your carb.
If so, Check your pop-off pressure!

 

[N-O-V8-R]

I'm kinda going through similar issues with the 120 on my 540t. I just put a new kit in the carb as the engine has sat for the past 7 months. Starts fine however when running, I notice the ibec light going on and off and some of my servos twitching and it won't go past 1/2 throttle and dies. Run straight off a battery and twitching and blinks stop but engine still won't go past 1/2 throttle. So I'm leaning towards a funky ignition with the glitching that's occurring. Changing needles didn't have any effect.


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Tighten the ring around your Spark-Plug Cap.
This is especially true if you have an angled cap, as some of these came out with wire that were a couple gages too small.
These need to be TIGHT fitting, or you will have all the troubles mentioned.
Also check the condition of the braided cable on the high tension lead.

 

[Robbins]

i find it queer that his ibec light would come on and off. leads me to think radio program error, broken wire inside the insulation or at a connector in the ibec circuit, or last, bad ibec.

 

[Bipeguy03]

did you recently rebuild your carb.
If so, Check your pop-off pressure!

Nope, it's a brand spanking new engine. Still haven't got a chance to run it, waiting on the weather to turn by I'll get her figured out

 

[Terryscustom]

Nope, it's a brand spanking new engine. Still haven't got a chance to run it, waiting on the weather to turn by I'll get her figured out

Yea, probably not pop-off pressure. It may have a defunct factory carb with the severity of the symptoms. I have had two DOA DLE carbs so I would not rule that out. When they work, they work just like a Walbro, when they don't...you get what you have. One that I had that was DOA would run great but no matter how far I went out on the low needle it would stumble and die like the L was lean. Took it apart, checked everything, tried again......nadda. Called up VVRC and had a new warranty carb in four days, sent old back. Ran like a watch from first start.

 

[jhelber08]

Tighten the ring around your Spark-Plug Cap.
This is especially true if you have an angled cap, as some of these came out with wire that were a couple gages too small.
These need to be TIGHT fitting, or you will have all the troubles mentioned.
Also check the condition of the braided cable on the high tension lead.

I suspect ignition is culprit, braided cable is a little worn in spots and it probably needs new caps. The ignition came out of my slick which was the first big plane I ever put together and I used zipties wrapped in tygon and that started eating through the case. I have a brand new ignition and I was going to use it and send the old one in to get refirbished but then I thought, I've never had a single issue with this ignition/engine so I used the old one...guess that's what I get for thinking. Anyhow, the new ignition will be the first thing I try when I get home.

i find it queer that his ibec light would come on and off. leads me to think radio program error, broken wire inside the insulation or at a connector in the ibec circuit, or last, bad ibec.

Light only goes on and off when I have the ignition hooked up and engine running with ignition supplied from the ibec. When I hooked a life battery straight to the ignition, engine still would not go above half throttle and the ibec light will stay solid. I was thinking at first a loose connection on the extension from my rx to ibec but being that the light stays on with the engine running and not hooked through ibec proves that's not the issue.

As for programming, that plane is identical to another plane I have from which I copied the model in my transmitter and only changed settings for matching servos/setting up throws/etc.

Appreciate the input, i'm sure i'm on the right track with it, just won't have the chance to try anything until I get home from offshore. It sucks being out here for 3 weeks knowing I got a sick airplane at home...lol

 

[Terryscustom]

I'll be curious on your findings on the ignition swap. Maybe noise from the damaged shielding is just over powering the IBEC filter.

 

[jhelber08]

I'll be curious on your findings on the ignition swap. Maybe noise from the damaged shielding is just over powering the IBEC filter.

Will definitely share the findings. I more or less wanted to get it out there, not so much for advice, but for somebody else to see a list of symptoms and how it was troubleshot and what the cure ends up being. Although it is reassuring that my initial thoughts are the same as everybody's suggestions.

Also, on the topic of ibecs, your statement brings up a good point. I think alot of people (just from reading other forums) are under the conception that ibecs isolate interference from ignition to the receiver when really it is just a filtered signal. Theres a big difference between isolating vs filtering. For that reason, I stayed away from them until I got the wild hare to try one and I liked the fact that I only had 2 batteries to worry about instead of 3. Now if they had a 5 port charger so I could have 1 ign battery and 2 sets of rx batts charged at once so I wouldn't have to charge at the field for a day of flying, I'd drop the ibecs but thats just me being lazy