int cutoff=90;   // Set Engine Cutoff time (If you're using relay, do not set timing under 40ms)
int dly=50;       // Set Delay time before next Upshift
int i;
const int MIN_CUTOFF = 60;
const int MAX_CUTOFF = 110;

void setup() {
  pinMode(2, INPUT_PULLUP);   // Sensor pin
  pinMode(5, OUTPUT);         // Relay Pin
  pinMode(6, OUTPUT);         // LED pin
  pinMode(3, INPUT);         //Increase cutoff time +
  pinMode(4, INPUT);         //Decrease cutoff time -
  digitalWrite(5, LOW);      // Set Relay on low State
  digitalWrite(6, HIGH);      // Turn on LED
  digitalWrite(3, HIGH);
  digitalWrite(4, HIGH);
}

void loop() 
{
  int snsrstate=digitalRead(2);
  int Increase=digitalRead(3);
  int Decrease=digitalRead(4);
//================================
  if (Increase == LOW && Decrease != LOW) 
  {
    if (cutoff + 10 <= MAX_CUTOFF) 
    {
        cutoff += 10;
    } 
    else 
      {
        cutoff = MAX_CUTOFF;
      }
  } else if (Decrease == LOW && Increase != LOW)
  {
    if (cutoff - 10 >= MIN_CUTOFF) 
    {
        cutoff -= 10;
    } 
    else 
      {
        cutoff = MIN_CUTOFF;
      }
  }
//===============================
  if (snsrstate==HIGH) 
  {
    i=0;
    delay(50);
  }
  if (snsrstate==LOW && i==0) 
  {
    i+=1;
    digitalWrite(5, HIGH);
    digitalWrite(6, HIGH);
    delay(cutoff);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
    delay(dly);
  }
 
}