Evolution
FORD 4.6 and 5.4 Liter
17
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.
