Speedometer Cable; Mass Air Sensor; Oxygen Sensors - Factory Five Racing MK4 ROADSTER Assembly Manual

Speedometer cable

From 1983.5 to 1993 Mustangs used a mechanical speedometer with a cable which had a plastic gear c-
clipped on to its end, which was inserted into the driver side of the transmission. This plastic gear is
designed to translate the proper vehicles speeds that will correspond with the ratio of the gears in the
rear axle. Below is a chart describing which plastic gear is used with the corresponding rear axle gear
ratios. From 1986 to 1993 the mustang still retained a mechanics cable speedometer, and plastic gear on
the transmission end, however an electronic sensor was added on the transmission end to send a signal to
the vehicles computer. From 1994 to 2004 there was only the electronic sensor with plastic gear
attached to the transmission. The speedometer translated the electronic signal to display the vehicles
speed. The 1986 to 1995 cable, sensor and gear assembly will fit into the 1996 to 2004 transmissions.
1983-89 3.27:1(19)
1990-98 3.27:1(21)
*23 Tooth gear may not be completely accurate in the selected application without
changing the transmission drive gear.
1983-98 19 Tooth Pink C0DZ-00017271-B
1983-98 20 Tooth Black C1DZ-00017271-A
1983-98 21 Tooth Red
1983-98 23 Tooth White E6MS-0017271C-M

Mass Air Sensor

Mass air sensors are devices used to measure air flow into the engine for the vehicles computer. These
started to be used in Mustangs in 1989 and are still being used.
1986-1988 engines measured air pressure in the intake to provide information for the computer. Mass
air sensors send more accurate information to the computer than speed density sensors. A speed density
('86-88) controlled vehicle can be converted to mass air by changing the computer, adding the sensor,
and running 4 wires (two to the computer, one positive, and one ground). There is a flexible rubber
elbow that connects the mass air meter to the throttle body, which is required for use in a Factory Five
kit. When a 1996-2003 Mustang is used as a donor for a Roadster kit, the stock air filter and filter box
are required to complete the kit.

Oxygen Sensors

Oxygen sensors are placed in the exhaust to measure the oxygen content of the exhaust. This
measurement is used by the computer to determine whether fuel delivery to the engine needs to be
increased or decreased. From 1986-1995 Ford Mustangs used two oxygen sensors, one in each side of
the exhaust system. From 1996-2004 Mustangs used four oxygen sensors, two per side. At full throttle
the oxygen sensor signals are not used by the computer, because the computer has a built in program to
run the engine rich at wide open throttle. Oxygen sensors will usually be most effective when placed
near the collection point of headers because the exhaust will remain very hot, and an average
3.55:1(20) 3.73:1(21)
3.55:1(23) 3.73:1(23*)
C40Z-00017271-A
www.factoryfive.com
4.10:1(23)
4.10:1(23*)
544
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