Rough running 912iS

by Harlan H. Henke in 912iS Technical Questions 3 weeks ago

I have a Van’s RV-12iS that I built with about 125 hours on it since first flight early in 2024. I’ve had no problems with the Rotax 912iS. I’d been flying for about 45 minutes this past Monday and was climbing out from a touch & go. About 700 feet AGL (1650 MSL), it started running rough. I couldn’t tell that it had lost any power. I backed the throttle out a bit, lowered the nose and about 10 to 15 seconds later it smoothed out. Went to full throttle again and climbed to 6500 feet AGL circling the airport with no problems. Flew 45 minutes to my home field and landed with no problems. There were no abnormalities on the engine information screen of my Garmin G3X. No error messages. I downloaded the data file from the G3X and cannot see anything that looks out of place. Looking for a BUDS to look at the Rotax data directly. I’m planning on pulling the spark plugs to inspect and replace. Anyone else experience anything like this? Suggestions?

Re: Rough running 912iS

by Alex Tsai » 3 weeks ago

Alex Tsai

2 2 19

Harlan,

I've ran into times like this before. Felt the roughness for a split second but no warning message nor a warning light.

You might also want to pull the cap and check for corrosion and resistance (about 5 ohms). Corrosion typically build up easier on the ignition cable side (See picture attached) than the side spark plug connects to, but always check both. That's usually what I found when I had slight engine roughness.

Clean the spark plug and check for a good and healthy spark before you replace them especially if you're using Rotax plugs. Not the cheapest. If you run Unleaded gas, your plug shouldn't look too bad with 125 hours on it.

Hope this helps.

44375_2_IMG_3947.jpeg (You do not have access to download this file.)

Thank you said by: Harlan H. Henke

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Re: Rough running 912iS

by Kristof » 3 weeks ago

Kristof

4 44 89

Hello

First don’t change any thing before reading data with BUDS . Canging spark plug is idiot because if one missrun the engine can’t run back well as you say.

Rgds

Kristof

Thank you said by: Harlan H. Henke

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Rough running 912iS

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