Buggy Engine Sound (pitch)

Hello!

My engine sound works great for the first gear, but the pitch gets buggy once the car reaches second gear. Can anybody find what is causing the issue?

It has worked in the past, but adding the turbo functionality messed it up.

 void EngineSound ()
     {
         int gears = gearRatio.Length;
         int i;
 
         for (i = 0; i < gears; i++) {
             if (gearRatio [i] > currentSpeed) {
                 break;
             }
         }
         float gearMinValue = 0.00f;
         float gearMaxValue = 0.00f;
 
         if (i == 0) {
             gearMinValue = 0;
         } else {
             gearMinValue = gearRatio [i - 1];
         }
 
         // Turbo
         if (turboOn == false && currentSpeed < topSpeed) {
             gearMaxValue = gearRatio [i];
         } else {
             gearMaxValue = gearRatio [3];
         }
         if (started) {
             float enginePitch = ((currentSpeed - gearMinValue) / (gearMaxValue - gearMinValue)) + 1;
             GetComponent<AudioSource> ().mute = false;
 
             // Turbo
             if (turboOn == false && currentSpeed < topSpeed) {
                 GetComponent<AudioSource> ().pitch = enginePitch;
             } else {
                 GetComponent<AudioSource> ().pitch = 1.7f;
             }
         } else { 
             GetComponent<AudioSource> ().mute = true;
         }
     }

Thanks a lot in advance!