Evolution FORD 4.6 and 5.4 Liter
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The numbers on this screen represent the circumference (in mm) of your tire
size. The default value the Evolution displays is the current value stored in
the PCM. Adjust the tire size by pressing the [UP] and [DOWN] arrow keys.
The following table will help you determine your tire circumference by
matching your tire size with the common sizes listed. For example, if your
tire size is 285/ 65-18, the value (circumference) you enter into the Evolution
is 2600. You may also use the formula provided to determine your
approximate tire circumference. Finally, you may also measure your tire’s
circumference by marking your tire and rolling it one complete revolution
and measuring the distance in inches or millimeters. If you measure in
inches, multiply the distance by 25.4 to convert to mm. (ex. 91.3 inches x
25.4 = 2319 mm). The range of change is from 2000mm to 3500mm in
increments of 1mm.
Width Ratio Rim Circumference Tire Size
265 70 16 2441mm 33 2632mm
275 70 16 2485mm 35 2792mm
305 70 16 2617mm 37 2951mm
215 75 16 2289mm 38 3031mm
245 75 16 2430mm
265 75 16 2524mm Circumference Equation:
285 75 16 2618mm [(width * ratio * 0.02) + (rim * 25.4)] * 3.1415
295 75 16 2666mm Steps:
305 75 16 2713mm 1. Multiply Width, Ratio and 0.02
315 75 16 2760mm 2. Multiply Rim and 25.4
325 75 16 2807mm 3. Add Step #1 with Step #2
265 70 17 2521mm 4. Multiply Step #3 with 3.1416
285 75 17 2698mm 5. The result will be the circumference of your tire in mm.
315 75 17 2840mm
275 65 18 2559mm
285 65 18 2600mm
285 60 18 2510mm
325 60 18 2660mm
Caution: When adjusting the following values, it is highly advised to make
gradual changes as opposed to aggressive changes. This will help avoid
possible powertrain damage.
Idle Speed
This adjustment modifies the base Idle Speed of the engine. Select the RPM
you would like to add to the base idle speed. For example, if the normal base
idle is 600 RPM and you want 725 RPM, set the option value to 125 RPM.
(600 + 125 = 725) This option will only raise the base idle, not lower it.
WARNING Idle speeds above 800 RPM may cause vehicles with
automatic transmissions to "creep" when stopped while in gear, requiring
additional pressure on the brake pedal in order to keep the vehicle
stationary.
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