I have a 912ul on a 94 KF model 4.

Went flying today and it was chilly out around 32 degrees at the runway with high levels of moisture and low clouds. I did my normal run up and waited till the plane was warm having little issue. My carb sensor was showing just around 10C (50F). My carb sensor has a yellow arch between +/- 10C. Which I think signifies the spread in which there needs to be consideration for icing.

As I took off the engine had more vibration than usual. It didn't sound rougher just little more vibration (engine related? Rubber stuffer cause of cold?). We did a few patterns and I noticed quickly that the carb sensor was showing an average of 4C. When pulling carb heat it would move again back towards 10C.

We decided to fly off to the next airport and along the trip it was showing 0C and the engine was beginning to sound rougher. I pull carb heat as I know the signs of carb icing. The engine had a little dip in RPM but my carb temps did not rise much past 3C-5C. The increase in temps was not impressive.

The plane gave a small hiccup and I turned around and headed back. As I was pulling carb heat on and off as we flew it was again not increasing carb temps by a considerable amount. It was dropping RPMS tho. At one point I had carb heat half open, then when I pulled it full open the engine gave a cough.

Can all this be attributed to just flying in too cold of weather?
Was there a upgrade on the carb heat that my old 92 doesn't have?
I live in the Pacific northwest. Lots of rain and humidity. Is one of those carb heater kits that works off your coolant recommended?

Am I being a wimp?
  • Re: Engine issues on cold day.

    by » 2 years ago

    Is your Carb Temps Sensor measuring the temp of the Carb Body?, The Intake AirTemperature?, Or the Manifold Air Temperature?
    50° would be a great Manifold Temp but a lousy Intake Air temp.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated.

  • Re: Engine issues on cold day.

    by » 2 years ago


    Thanks for the response. The sensor I have is a threaded sensor that sticks into the intake side of the carb with a cork gasket and silicone. So this should be intake air. I agree very lousy temperature. Outside temp was around 32F, low ceiling, with high humidity. I have a feeling this was purely a icing issue. I am going to make another post about the carb heater kit that uses coolant to warm the carb. Please look out for it.

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