El primer error que tienes es este
tm1637.set(BRIGHT_TYPICAL);//BRIGHT_TYPICAL = 2,BRIGHT_DARKEST = 0,BRIGHTEST = 7;
tm1637.init();
Que debe ir al revés.
El resto del código tmb esta mal armado.
Este es un código que muestra en el TM1637 RPM hasta 9999
#include "TM1637.h"
#define CLK 2 //pins definitions for TM1637 and can be changed to other ports
#define DIO 3
const int hardwareCounterPin = 5;
const int samplePeriod = 1000; //in milliseconds
const float pulsesPerMile = 4000; //This value is different for different vehicles
const float convertMph = pulsesPerMile/3600;
unsigned int count;
float mph;
unsigned int imph;
int roundedMph;
int previousMph;
int prevCount;
int8_t TimeDisp[] = {0x00, 0x00, 0x00, 0x00};
TM1637 tm1637(CLK,DIO);
void setup()
{
tm1637.init();
tm1637.set(BRIGHT_TYPICAL); //BRIGHT_TYPICAL = 2,BRIGHT_DARKEST = 0,BRIGHTEST = 7;
Serial.begin(9600);
Serial.println("Startup...");
TCCR1A = 0; //Configure hardware counter
TCNT1 = 0; // Reset hardware counter to zero
}
void loop() {
unsigned long tmp;
bitSet(TCCR1B, CS12); // start counting pulses
bitSet(TCCR1B, CS11); // Clock on rising edge
delay(samplePeriod); // Allow pulse counter to collect for samplePeriod
TCCR1B = 0; // stop counting
count = TCNT1; // Store the hardware counter in a variable
TCNT1 = 0; // Reset hardware counter to zero
mph = (count/convertMph)*10; // Convert pulse count into mph.
imph = (unsigned int) mph; // Cast to integer. 10x allows retaining 10th of mph resolution.
Serial.println(imph);
TimeDisp[0] = imph / 1000;
tmp = (imph - TimeDisp[0]*1000);
Serial.println(tmp);
TimeDisp[1] = tmp/100;
tmp = (tmp - TimeDisp[1]*100);
Serial.println(tmp);
TimeDisp[2] = tmp/10;
tmp = (tmp - TimeDisp[2]*10);
TimeDisp[3] = tmp%10;
tm1637.display(TimeDisp);
}