RPM LOST ON IGNITION CHECK

by WATERINCKX in 912 / 914 Technical Questions 6 years ago

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Re: RPM LOST ON IGNITION CHECK

by Garrett Wysocki » 6 years ago

Garrett Wysocki

1 572 1.45k

Make sure the carburetor piston slides up and down easily. Sometimes they get gummed up and cause similar issues. they have to move freely.

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Re: RPM LOST ON IGNITION CHECK

by Kevin Stewart » 6 years ago

Kevin Stewart

3 400 1.18k

"swapped input coil harnesses and p leads which did lead to opposite switch making the larger drop..."

If swapping the input connector over causes the fault to transfer to the opposite ignition then the fault must be ignition and not carburation. The input connector comprises of the following:
1. two inductive trigger coils
2. the ignition charging coil
3. the kill switch connection

You can measure the resistance on the two charging coils and they should be similar and be within the published limits. I cannot imagine that the kill switch input would give your symptoms unless you had some very odd modulation on that pin. A problem with the trigger coils could give you a timing problem. The ignition module only knows which timing signal to use based on their amplitude. If you have a low output from one of the coils then it is quite possible that the module will think that it is in the cranking phase of engine start and will apply the appropriate ignition timing.

If you have access to an ignition strobe light then you can turn the engine to TDC and paint a white mark on the flywheel and on the crankcase housing. If you observe the timing marks when the engine is running they should appear fixed at all RPM on both ignitions. If they are not then you know that you have a timing issue. The fact that swapping the trigger coils over moves the fault to the opposite circuit says that you probably have low output from one of the coils. You could measure the voltage from each coil with a multimeter set to AC volts. The would identify the problem coil. Alternatively resistance measurements might shed some light on the fault. I would wiggle the wires whilst making the measurement in case there is a wire break.

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Re: RPM LOST ON IGNITION CHECK

by Clayton Dillard » 6 years ago

Clayton Dillard

0 5 0

Delayed reply here, apparently I had a bad ignition module that resulted in the larger drop in one side. After troubleshooting everything else, I borrowed a friend's module and the problem was solved...

Thank you said by: RotaxOwner Admin

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Re: RPM LOST ON IGNITION CHECK

by Wilfred » 5 years ago

Wilfred

0 3 1

I have a similar problem. What aircraft is this engine in? Can you try the test with open engine cowling and see if the problem is still there. Please let me know. It could be heat related issues inside the engine cowling.

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Re: RPM LOST ON IGNITION CHECK

by WATERINCKX » 5 years ago

WATERINCKX

1 5 0

The engine is installed on a CTLS from Flight Design.

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RPM LOST ON IGNITION CHECK

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