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Replacing fuel injectors – Mustang Cobra

This article describes how to remove and replace your fuel injectors on your 1996-1998 Mustang Cobra.  If you are just replacing injectors 1 or 5, you do not need to remove the upper intake manifold for access.  Just the strut tower brace has to come out for easier access.

Project Time:

A couple of hours

Tools Needed:

  • Socket set with various extensions
  • Sandwich bags to hold removed bolts.  Top tip: I usually just label the bag with a Sharpie indicating what they are from and what size they are.
  • Fuel line removal tool
  • A few extra O-rings just in case you ruin one.
  • A fire extinguisher.  You are dealing with fuel and you want to be able to put out a possible fire if there are fuel leaks.

Removal of injectors

Figure 1
  1. Disconnect the IAT and MAF sensors.  Remove the air intake system as a unit by unbolting the airbox from the body and loosening the clamp at the throttle body.
  2. Remove the strut tower brace.  There are five 10mm bolts.
  3. Be sure to depressurize the fuel system before disconnecting any fuel lines.  You can remove the fuse for the fuel pump while the car is running and let it die.  There is no shrader valve like Turbo Regals.
  4. The upper intake has to come out.  Top tip: Take pictures of everything to ensure you can get it back together correctly.
    1. Mark and disconnect all vacuum hose connections to upper intake manifold components.
    2. Disconnect the throttle body and accelerator cable brackets
    3. Disconnect PCV hose, then remove idle air control valve inlet tube.
    4. Disconnect leads to the EGR, EGR vacuum solenoid, IAC and DPFE sensor.  I may have forgotten something but just take a careful look at the upper and disconnect anything that looks like it needs disconnecting.  The EGR and IAC can remain bolted on, just disconnect the lines.
    5. Remove the bolts for the upper intake.  There are 7 of them as shown in the picture below:

      Figure 2
  5. Remove the upper intake manifold.
  6. Disconnect the fuel chassis inlet and outlet fuel hoses from the fuel supply manifold.  Disconnect the fuel lines by removing the retaining clip and then using the fuel line disconnect tool.
    retaining clip
  7. Remove the four fuel rail retaining bolts.  These are 8mm and are labeled (6) in Figure1 at the top of the article.
  8. Remove the injector harness connectors and label them with tape so you can get them back to the correct cylinder.  Just as a precaution.
  9. Carefully disengage the fuel rail assembly from the fuel injectors by lifting and gently rocking the rail.
  10. Remove the fuel injectors from the intake manifold by lifting while gently rocking them from side to side.  Make sure the O-rings are intact and not left in the manifold or rail.
  11. Place all removed components on a clean surface to prevent contamination by dirt or grease.

To Install

  1. Lubricate the injector O-rings with clean engine oil only.
  2. Install injector by easing it into the fuel rail making sure it seats properly.  You will be able to tell.
  3. Seat the injectors in the manifold and double check that they are seated.
  4. Hold the fuel rail assembly in place and install the 4 retaining bolts finger-tight. Then, tighten the bolts to  71-106 inch lbs. (8-12 Nm) for the 4.6L SOHC and DOHC engines.
  5. Connect the fuel supply and return lines.
  6. Attach the vacuum hose to the fuel pressure regulator.
  7. Connect the fuel injector wiring harness at the injectors.
  8. Install the upper intake, air intake and throttle body assembly.  Inspect the gasket.  It is re-usable but if you need a new one after all of these years, they are  $35 at Autozone
  9. Make sure to tighten the bolts in the sequence below:  Torque them to 8 ft/lbs.

    Intake manifold torque sequence
  10. Connect everything you disconnected in the removal process.  Refer to pictures you took if needed.
  11. Start the car and inspect for leaks very carefully.  Have a fire extinguisher handy just in case.  Every garage should have one.
  12. Test drive the car.

If you are just replacing one injector because it is clogged, it is a good idea to do an injector service because the rest may have been on their way.  It is probably a good time to Seafoam the IMRCs.

And you saved roughly $200 in labor fees