Nitro Engine Problems

by Abhinav
(New Delhi India)

My engine catches speed for some time before it idles. Also its eating glow plugs. Why?

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Nitro Engine Problems

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Jan 04, 2009
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Maybe too rich?
by: Matt

Hello Abhinav,

Let me make sure I understand the problem. When you try to throttle the engine down to idle, it picks up speed before coming to an idle?

It's difficult to know what the problem is with limited information as to what exactly the engine is doing. I know that information is sometimes difficult to relay in writing.

However, it sounds to me that you may be running your engine rich. Perhaps on the low end needle, maybe even the high speed needle.

An engine runs the fastest at the perfect combination of fuel and oxygen. So if your engine is running with too much fuel, it will actually increase in speed when the fuel is reduced until it gets to that "sweet spot", then the engine speeds will reduce as the fuel is cut back.

When shutting the throttle you are also decreasing the oxygen, so it's combination of getting the right amount of fuel and air.

I would suggest trying the < a href="http://www.hooked-on-rc-airplanes.com/nitro-engine-tuning-tips.html#1">pinch test at both full throttle and idle. If the RPM's increase drastically then you are running your engine too rich.

Another sign of running the engine too rich is an excessive amount of oil and goo coming out the exhaust.

Running the engine too rich could also be fouling your glow plugs.

Just keep in mind when adjusting your engine that you don't want to make the engine too lean because that will ruin the engine. The engine RPM's should rise slightly when doing the pinch test.

I hope this helps, let us know how it turns out.

Good luck!

Matt

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Jan 04, 2009
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Submitted by: Matt

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Hello Abhinav, Let me make sure I understand the problem. When you try to throttle the engine down to idle, it picks up speed before coming to an idle? It's difficult to know what the problem is with limited information as to what exactly the engine is doing. I know that information is sometimes difficult to relay in writing. However, it sounds to me that you may be running your engine rich. Perhaps on the low end needle, maybe even the high speed needle. An engine runs the fastest at the perfect combination of fuel and oxygen. So if your engine is running with too much fuel, it will actually increase in speed when the fuel is reduced until it gets to that "sweet spot", then the engine speeds will reduce as the fuel is cut back. When shutting the throttle you are also decreasing the oxygen, so it's combination of getting the right amount of fuel and air. I would suggest trying the < a href="http://www.hooked-on-rc-airplanes.com/nitro-engine-tuning-tips.html#1">pinch test</a> at both full throttle and idle. If the RPM's increase drastically then you are running your engine too rich. Another sign of running the engine too rich is an excessive amount of oil and goo coming out the exhaust. Running the engine too rich could also be fouling your glow plugs. Just keep in mind when adjusting your engine that you don't want to make the engine too lean because that will ruin the engine. The engine RPM's should rise slightly when doing the pinch test. I hope this helps, let us know how it turns out. Good luck! Matt

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