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Sputtering at idol

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Sputtering at idol

Old 04-06-2006, 01:32 AM
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Default Sputtering at idol

My PST J600R has been working fine untill the last few flights. It will start just fine but when it is at idol it will pop and sputter. As soon as you bring the RPM's up it goes away. It wont flame out or anything but I dont know why it would be doing this all of a sudden. On another note I noticed that I have an exessive amount of oil residue in my pipe after shutdown. I dont know if the two are related but any help would be grest.

Thanks

P.S I also made sure that I am using exactly one quart of turbine oil to exactly five gallons of fuel
Old 04-06-2006, 07:57 AM
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Default RE: Sputtering at idol

Make sure your Kerosene or Jet A1 is fresh. If it sits for a few weeks moisture is absorbed into the fuel & it deteriorates.
One of the symptoms is spluttering at idle, & can cause flameouts when the throttle is opened quickly.

Regards
Old 04-06-2006, 11:32 PM
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Default RE: Sputtering at idol

Hi erapoza,

I can't say for sure, but Jim may have the right track on this one. It could just be a bad batch... If it were a fuel vaporisation problem, you'd likely notice much more than just sputtering at idle. Clogging one or more of the 12 injector nozzles, or any damage to the combustion chamber / atomizer tubes would cause much more erratic behaviour and uneven combustion. Such damage is very unlikely, particularly with the injectors since the engine incorporates on-board filters as a 'last chance' debris trap.

The oil mixture is really just a line drawn in the sand on all the turbines today, and you'd likely find that you can deviate it a few percent without affecting things much. I'd have a hard time telling if fuel was 5.5% vs. 4.5% based on how an engine runs. I've never deviated a full percentage point, but I doubt you'd notice it. PST does however maintain that the warranty is only valid with a 5% mixture, +/- a reasonable amount for measuring inaccuracy only... Basically take a 20L jug and pour in a quart and slosh it around thoroughly. You'll be fine and warranty will cover you, even though its not bang on 5%.

Back to the idle question. I've seen other brands do this, which will remain nameless, and its nothing out of the ordinary. If it really bothers you, try manually calibrating the idle speed 2 or 3K higher. The ECU recalibrates the idle speed each time it starts, and again if you select the idle adjustment while running. To set a new idle speed and expect the calibration routine to target that level (58K for example as apposed to 55K), you'll need to set the idle speed to 58K in the setup menu while the engine's not running.

Kelly
Old 04-09-2006, 12:35 AM
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Default RE: Sputtering at idol

Thanks for all your help! I am pretty sure it was moisture in the fuel. I tried some fresh fuel from another container and the problem went away. On another note, the ramping setting you gave me worked like a charm. It has much better throttle response now.

Thanks.

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