IC Engine Throttle Servo Problem!

Hi guys! I’m building a fixed wing standart plane with Pixhawk Cube and PX4. Here is my problem. Engine throttle arm and servo are not coherent. When servo reached nearly %80 engine arm is already reaching %100. How can I fix this problem. I changed PWM_MAIN_MAX5, PWM_MAIN_MIN5 parameters but I didn’t understand the logic?