I am using the I term, it just looks different. The D term is harder to implement because of the large dt. This problem is odd because of the large resolution of the sensor, the large dt compared to the changes in direction/speed, and the large number of 0's in my variable chg (even at a larger dt than I've chosen). Please show me how to implement the conventional PID within these limits? Are you suggesting my pressure sensor is inappropriate? Then why does it nearly work with only 3 lines of pseudocode? I don't mean to be difficult. Please teach me or show me some untested code that may help?