Quote:
Originally Posted by oneintheory
the speedo reads high, but the ECU knows the actual speed of the car, and the ECU controls the odometer, resulting in accurate mileage. You also get accurate MPG data in spite of the speedo.
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How does the ECU know the actual speed? I mean, it can know the actual number of axle revolutions, but it doesn't know the circumference of the actual tires. That is, if I had 75" cir. tires, and switched them to 77" cir., how would the ECU know about that? Since the ECU is programmable, is that a parameter you can input if you change your tires, perhaps?