Mustang Universal Mass Air Flow EFI Harness 5.0/5.8 Installation Instructions

Pre-Installation Notes:

• This system is designed to install Mass Air Flow based Ford EFI 5.0 & 5.8 engines.
• Make sure that all the components you have are compatible before installing them.
• Intakes are fairly interchangeable, make sure the upper and lower intakes match, and the lower intake has a port for the Air Charge Temp sensor (ACT) sensor.
• The fuel rail will dictate which side the intake faces, make sure you have the correct one. This harness is set up for a passenger side facing intake when in stock form.
• This harness does not include provisions for emissions and is not intended for installation on emission controlled vehicles.
• The distributor should be specific for your engine (5.0L / 5.8L) and have the TFI Ignition Module mounted onto the side.
• This harness is set up for a “High Output” firing order of 1-3-7-2-6-5-4-8 in its stock form. Make sure your camshaft and computer match this order.
• Ford EFI systems were not intended for use with long tube headers. The Oxygen Sensors are less accurate (due to dissipated exhaust heat) when mounted further down stream from the cylinder head. However this harness will work with all exhaust systems.
• Always disconnect the battery when working on vehicles fuel or electrical systems. Any electrical spikes can damage parts of the fuel injection system.
• Use extreme caution if and when welding on any vehicle with a fuel injection system.

Pre-Installation Instructions:

Install the lower intake, fuel injectors, and fuel rail on the engine if not already installed. Remove the upper intake if it is installed and install stock fuel pressure regulator. Plumb fuel lines with appropriately rated line. Use caution when working on fuel system, 40-100 PSI can be held within system. To release fuel pressure, remove fuse or relay to fuel pump(s), then start engine and allow it to stall. Crank starter for several seconds to insure all pressure has been released.

Before installation spread out the harness in a well lighted open area to identify all the connectors and become familiar with what will need to be done.

Connector List:

1. EEC Computer connector
2. Inertia Fuel Cutoff Switch
3. Ignition, Start, Tachometer & Check Engine Light connections
4. Self-Test connectors
5. Transmission ID Plugs
6. Relay Block
7. Fuse Block and Battery connection
8. Mass Air sensor
9. Ground
10. Throttle Position sensor
11. Idle Air Bypass
12. Engine Coolant Temp Sensor
13. Barometric Pressure sensor
14. Injectors
15. Air Charge Temp sensor
16. TFI Distributor connector
17. SPOUT Connector
18. R & L Oxygen sensors
19. Vehicle Speed sensor
20. Fuel Pump Connection
21. Ignition Coil plug
22. Alternator connection

Installation Instructions:

1. Lay the harness into the engine compartment with the relay and fuse blocks on the passenger side.
2. Locate where in the firewall you wish to route the computer plug and other dash connections. Using the grommet supplied, cut the appropriate hole in the firewall.
3. Pass the engine section of the harness through the firewall. Route as much of the harness as possible before mounting the computer or covering the harness. This ensures a quality installation.
4. Remove the last bolt holding the lower intake down on the passenger side. Install #9 engine ground and torque the bolt back down to specifications. This is extremely important and should be the first connections made!
5. Install all eight fuel injector connectors starting with cylinder #1 and working your way around. Connecting the injectors now helps get the majority of the harness into position.
6. Connect #12 Engine Coolant Temp sensor and #15 Air Charge Temp sensor.
7. Route #18 Right & Left O2 sensors, #19 Vehicle Speed sensor, and #20 Fuel Pump power wires down to their locations under vehicle. Route #19 Vehicle Speed sensor and #20 Fuel Pump power connectors along the left frame rail. Keep them away from hot exhaust moving parts like driveshaft.

8. Weld exhaust bungs into both sides of the exhaust approximately 9–12 inches from the last cylinder head exhaust port or 3" from the collector. Clean any debris from oxygen sensor ports and threads.

   A) Use a small amount of anti-seize on the threads when installing Oxygen Sensors. Use SG23 Oxygen sensors with short headers. Use SG40 Oxygen Sensors with long tube headers.

   B) Connect #18, oxygen sensors to their connectors and attach any free harness to the firewall or frame to keep them from falling against the exhaust.

9. Install Vehicle Speed Sensor between the transmission and speedometer cable. Route #19 Vehicle Speed Sensor connector along the left frame rail and plug into the Vehicle Speed Sensor.
10. #20 is a 14Ga pink wire to power your fuel pump(s); you will need to splice this wire if you are using 2 fuel pumps that are not mounted together. Make sure the fuel pump(s) are well grounded.
11. Carefully route #21 Ignition Coil connector along firewall and fender to the coil. Keep Radio power wires and antenna cables away from Ignition Coil to prevent future distortion or interference.
12. #3 is a group of wires under the dash.

Color | Printing | Purpose

• Orange | Keyed Run | Ignition Power Supply
• Purple | Start | Start Signal for ECM
• Green | Tach | Tachometer
• Tan | MIL Check Engine | Check Engine Light Negative
• Red | MIL Check Engine Positive | Check Engine Light Positive

A) Connect the Orange wire marked "Keyed Run" to the keyed ignition switch hot wire. This wire must have +12 volts with the key in run and start positions.

B) Connect the Purple wire marked "Start" to the keyed ignition start wire. This wire must have +12 volts only when the key is in the start position.

C) The Green wire marked 'Tach' is for your tachometer. Connect to your tach. Refer to the tachometer manufacturers information for any additional details.

D) Connect the Tan marked "MIL" and Red marked "MIL Power" to your check engine light. This must be a light that is not self grounding and needs two leads, both power and ground.

13. You can install the upper intake plenum onto the lower intake and install the throttle body to the upper intake. Now would also be a good time to finish the vacuum system.
14. Connect #10 Throttle Position sensor and #11 Idle Air Bypass.
15. Install the Mass Air Flow Meter, air filter and air tubes. Connect the MAF to the harness connection #8.
16. Mount the Barometric Pressure sensor to the firewall or inner fender and connect it to the harness at #13.
17. Before you install the distributor, make sure the engine is at TDC for cylinder #1 and you have mounted the TFI to the side of the distributor. Drop the distributor into position so the rotor is aligned with the 1 molded into the cap. Make sure there is enough room to rotate the distributor in the block 1/8th of a turn. You will need to rotate it to set the base timing to 10 degrees BTDC. Connect #16 to the TFI module on the distributor and make sure that #17 SPOUT connector is connected firmly. Only disconnect the SPOUT to check and set the base timing.
18. Locate #5 the transmission identification terminals near the Self-Test connectors. You need to plug the male terminal into one of the female terminals, depending on which computer type you are using. The male plug is labeled "TRANS" and the female plugs are labeled "AUTO" & "MAN." You need to identify your computer as an automatic or manual transmission computer by its sticker. If you are unsure which computer you have your local Ford dealer should be able to help.

A) If your computer is for an automatic transmission; connect "TRANS" plug to the Black "AUTO" plug.

B) If your computer is for a manual transmission; connect "TRANS" plug to the Gray "MAN" plug.

19. It is advised that you use an inertia switch to turn off the fuel pump(s) in the event of a crash. Under the dash is connector #2 for the Inertia Fuel Cutoff Switch. Mount the Inertia Switch completely upright and connect it to the harness. Mounting the switch any other way or bypassing this switch can cause risk or fire or loss of life. Before continuing, tap the switch until the button on top pops up and reset it. This will confirm its action and get you familiar with how it works.
20. Connector #1 is for the computer, make sure the computer pins are not bent or damaged. Then connect the harness with a 10mm socket. DO NOT use air or power tools to install this connector!
21. Next to the Fuse & Relay blocks is a large 10 Ga red wire connect this 10 Ga Red 3/8" terminal to Battery Positive or the starter solenoid.
22. #22 is ignition power wire for your alternator. It is not meant to charge the vehicle, but to turn the alternator ON when you turn the key to RUN. Consult your alternator installation manual for further instructions.
23. Please take the time to run a Self-Test at #4 prior to starting the engine. This will clue you in to any connections you missed, and give you a base line to compare future tests against.
24. If this is the first fuel injection installation on this vehicle run the fuel pump(s) for 30–60 seconds to create fuel pressure for the injectors. To do this, ground the terminal on the end of the larger Self-Test connector marked ECM 22-->VIP.

Codes 33, 44, 81, 82, 84, 85 and 94 are what's called "soft" codes and do not affect the engine fuel or spark programming. These codes will set due to the smog solenoids CANP, EGR, TAB and TAD being removed. Soft codes harmlessly stay dormant in the computer. Their purpose is to help aid in the repair of those systems. Soft codes will not turn on the Check Engine Light.

There is a resistor pack already installed in this harness for the EGR Valve Position Sensor. No other resistors are required.

Using the Check Engine Light:

The check engine light performs just the same as it would in any newer car, when the key is turned on (engine not running) the light will stay on till the engine starts. When the check engine light comes on during engine operation, it is an indication of a fault in the system. It will be necessary to have the computer perform a self test diagnostic procedure. The self test is divided into three specialized tests:

KEY ON ENGINE OFF SELF TEST: For this test the fault must be present at the time of testing. For intermittent problems refer to continuous memory codes.

ENGINE RUNNING SELF TEST: The sensors are checked under operating conditions and at normal operating temperatures.

CONTINUOUS MEMORY CODES: These codes are issued as a result of information stored while the vehicle was in normal operation.

READING THE CHECK ENGINE LIGHT: A service code is reported by a flash of the check engine light. All service codes are two digit numbers, such as 2-3. The light will display two flashes, then, after a two second pause, the light will flash three times. All self test codes (if any) will be displayed and then a delay of six seconds, a single half second separator flash and another six second delay and then the continuous memory codes will be flashed.

If the light remains on after the engine is running then follow the procedures below to have the check engine light flash trouble codes. Locate the V.I.P self test connectors and connect a jumper wire between the grey wire (VIP->CTS SPL) located in the large VIP connector and the tan wire (ECM 48->VIP) located in the single connector as shown in the drawing to the right.

Trouble Codes:

11 System PASS
12 High RPM
13 Low RPM
14 PIP circuit failure
15 ECG memory failure
16 RPM low for EGO test
18 SPOUT /IDM circuit failure
19 ECG internal voltage failure
21 ECT out of test range
22 MAP /BP out of test range
23 TP out of test range
24 ACT of test range
26 MAF out of test range
29 Vehicle speed sensor problem
31 EVP voltage below minimum
32 EVP voltage below closed limit
33 EGR valve opening not detected

34 EVP voltage above closed limit
35 EVP voltage above maximum
41 HEGO (R) sensor lean or defective
42 HEGO (R) sensor rich
44 Thermactor air system defective (R)
45 Thermactor air upstream during self test
46 Thermactor air not bypassed during self test
51 ECT indicated -40NF/open circuit
53 TP circuit above maximum voltage
54 ACT indicated -40NF/circuit open
56 MAF circuit above max voltage
61 ECT indicated 254NF/circuit grounded
63 TP circuit below minimum voltage
64 ACT indicated 254NF/circuit grounded
66 MAF circuit below minimum voltage
67 Neutral drive switch circuit open

74 Brake on/off circuit open during self test
75 Brake on/off circuit closed/ ECG input open
77 Brief WOT not sensed during self test
79 A/C on defrost on during self test
81 Air management 2 circuit failure
82 Air management 1 circuit failure
84 EGR Vacuum Regulator circuit failure
85 Canister purge circuit failure
87 Fuel pump primary circuit failure
91 HEGO (L) sensor lean or defective
92 HEGO (L) sensor rich
94 Thermactor air system inoperative (L)
95 Fuel pump secondary circuit failure
96 Fuel pump secondary circuit failure
98 Hard fault present FMEM mode

No codes = unable to indicate self test | Code not listed = Not applicable to this engine

The following diagram shows some of the sensor locations on a typical Ford 5.0 engine. The sensors not shown are mounted remote (off the engine) on the stock vehicle application. Your installation may require these items not to be mounted in the same location as on a factory installation. The numbers before the sensor names correspond to the numbers shown in the drawing.

1. Air Charge Temperature Sensor
2. Shorting Plug
3. TFI Ignition Module
4. Coolant Temperature Sensor
5. Idle Speed Control
6. Mass Air Flow Sensor
7. Throttle Position Sensor
8. Right O2 Sensor
9. EGR Valve Position Sensor
10. Injectors
11. Left O2 Sensor