Oscillating idle RPM
in 912iS Technical Questions
5 years ago
Hi
I have a 912 IS Sport motor with 260 hours. Over the last 30-40 hours I've noticed the RPM oscillates up and down (100-200 rpm) at a regular rhythm (every 5-10 seconds) after start-up. Over the following few minutes the magnitude of the RPM variation reduces (frequency of oscillation seems to remain the same) until after 5-10 minutes the motor idle RPM remains essentially constant.
There is no oscillation under load.
The longer it's been since the motor was last operated, the greater the magnitude of initial fluctation.
Fuel filter was replaced 5 hours ago. Indicated fuel PSI remains constant.
Any ideas as to the cause would be much appreciated.
Regards and thanks
George (Australia)
I have a 912 IS Sport motor with 260 hours. Over the last 30-40 hours I've noticed the RPM oscillates up and down (100-200 rpm) at a regular rhythm (every 5-10 seconds) after start-up. Over the following few minutes the magnitude of the RPM variation reduces (frequency of oscillation seems to remain the same) until after 5-10 minutes the motor idle RPM remains essentially constant.
There is no oscillation under load.
The longer it's been since the motor was last operated, the greater the magnitude of initial fluctation.
Fuel filter was replaced 5 hours ago. Indicated fuel PSI remains constant.
Any ideas as to the cause would be much appreciated.
Regards and thanks
George (Australia)
