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How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

Posted 7/18/2019 by Taylor Ward

How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

Check out our step-by-step instructions and video explaining how to install the MegaSquirt ECU on your Fox Body Mustang for complete custom tuning!

FOLLOW: mustang , 79 93 mustang , fox body mustang , tune

What comes with the MegaSquirt kit:
  • 1 MegaSquirt ECU
  • 6ft of Back Hose
  • Small Plastic T-Fitting
  • 6ft Serial Cable
  • 26 Pin Connector w/26 Leads
  • USB Thumb Drive w/Tuner Studio
  • Optional Equipment: Serial To USB Cable And Supported Wideband Gauges

Also note that the only item that is required for the installation is a modern laptop running a Windows OS. This MegaSquirt will fit 86’-93’ 302 or 351 based Mustangs. Also be aware that these instructions are for the current update and over time steps and processes can be changed with a software update from the developers.


Before installation you will need to print and read over the instruction manual first.
  1. Put vehicle on jack stands or a lift and disconnect the negative battery cable.
  2. Since you will be working under the dash, we recommend removing both front seats to give you more work room.
  3. On the passenger side of the car remove the frontward scuff plate retaining screw followed by the kick panel push pin.
  4. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  5. Pass the kick panel over the scuff plate and pull straight out on the panel to remove from vehicle.
  6. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  7. Locate the factory PCM and it may be in your best interest to disconnect a few electrical connections.
  8. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  9. Loosen the 10 mm bolt that secures the electrical connection to the EEC. Once the bolt is loose, disconnect the connection.
  10. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  11. Loosen and remove the 9/32” EEC cradle hold down bolt and slide the EEC out of the cradle and remove from car.
  12. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  13. Loosen and remove the (2) 7mm glove box hinge retaining screws and open the glove box and squeeze both sides together so that you are able to remove it.
  14. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  15. To remove the AC blower box, you will need to loosen and remove the upper bolt that is just behind the vent tube.
  16. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  17. Loosen and remove the small 7 mm retaining screws located directly underneath the box.
  18. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  19. Before dropping it dislodge the vacuum line and whenever you lower the box dislodge the electrical connection and it’s able to come out of the vehicle.
  20. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)
    How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  21. Dislodge the push pin that secures the sound deadening material and remove from vehicle
  22. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  23. Remove the factory EEC cradle and set aside. (The reasoning for removing all of these pieces is to expose the passenger side firewall grommet)
  24. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  25. Be careful to cut a small slit on the inside and outside of the grommet.
  26. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  27. Tape the provided vacuum hose to a long ¼” extension and carefully push it through the open slit from the last step.
  28. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  29. Once it comes out of the opening you can remove the tape and make sure about 2 ft of the hose is inside the car. (NOTE: use caution when pulling the hose through the grommet)
  30. If you are installing a wideband into the car use this time to cut small openings into the driver side firewall grommet. These cuts will need to be a little large than the passenger side because it will have to pass through an electrical connector.
  31. Tape the end of the wideband connector to the ¼” extension and feed through the opening like you did on the passenger side.
  32. Disconnect whichever oxygen sensor you may be replacing with the wideband sensor. (Note: in this video we are replacing the driver side)
  33. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  34. Loosen the sensor with a 7/8” wrench and remove from the midpipe.
  35. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  36. Take the wideband sensor and apply anti-seize if needed.
  37. Loosely tighten the new sensor because it will have to be removed again to properly calibrate.
  38. Feed the new wire alongside the existing harness.
  39. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  40. Tape the factory connector and secure it out of the way.
  41. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  42. Secure the wideband sensor wire alongside the existing starter wire and tuck out of the way.
  43. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  44. The PCM will need to be opened to configure the pre-installed oxygen sensor jumper and comes easily apart by removing the 4 phillips head screws and 2 hexagonal screws from the serial connection with a 5 mm socket.
  45. Now that the top cover is removed, the only jumper that should be changed is J6 and controls the oxygen sensor connectivity.
  46. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  47. With this jumper is also the pin labeled J8-29 and controls the passenger side bank, but since we are dealing with the driver side in this video, we are removing the jumper labeled J8-43.
  48. Reassemble the PCM and carefully tighten the retaining hardware.
  49. The wideband of choice in this video is an innovate wideband which means we will need to configure the provided 26 pin connector.
  50. The oxygen sensor input connection is located on pin 21 on the connector.
  51. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  52. The lead will install on the side with the larger holes and exit on the side with the smaller holes.
  53. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  54. Position the 2 covers around the connector and use the small hexagonal nuts and small screws to secure the covers as well as the wire holder to fill the remaining hole.
  55. Install the connector into the main port on the PCM.
  56. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  57. Use the small flat rectangular washers and screws to secure the 26-pin connector to the PCM.
  58. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  59. While the PCM is out of the car you will need to strip the wire.
  60. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  61. The PCM cradle requires modification to fit the MegaSquirt and is done so by using 2 pieces of foam tape to prevent metal to metal contact and reduce rattle noise.
  62. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  63. Plug in the factory connector and tighten the 10mm retaining bolt.
  64. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  65. Connect the provided serial cable to the PCM and tighten the thumb screw.
  66. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  67. Install the provided vacuum hose over the plastic barbed fitting.
  68. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  69. Position the PCM in the original location and reconnect any electrical connections that were disconnected for extra working space.
  70. Tuck the connections into the body of the car.
  71. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  72. Pull any slack out of the vacuum hose and route it alongside the existing wiring harness. (Note: make sure the vacuum hose isn’t pinched)
  73. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  74. Since there is a Vortech supercharger in this install we had to tap into an existing vacuum line that was previously ran.
  75. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  76. Wrap the serial cable behind the dash towards whichever side you are working on and safely secure this cable to an existing wiring harness.
  77. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  78. On the PCM remove the harness clip from the relay and position out of the way.
  79. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  80. On this car we are using a pillar pod so we took the time to organize the wiring and temporarily mounted the pod to the car.
  81. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  82. Next we ran the extended analog output wire from the wideband gauge towards the PCM.
  83. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  84. Secure the wire to any existing harness that runs the length of the dash.
  85. Slide a butt connector over the wire from the 26-pin connector and crimp it.
  86. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  87. Route the wire from the wideband towards the butt connector and cut to length.
  88. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  89. Strip the wire and twist.
  90. Insert into the butt connector and crimp. Tuck out of the way. (If needed you can add heat to seal)
  91. How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993) - How To MegaSquirt Your Fox Body Mustang 5.0 (1986-1993)

  92. Also, since the MegaSquirt ECU uses speed density as the primary fuel metering method, a mass air flow meter is no longer required and can be removed. (It is also in your best interest to cover the sensor connection and secure out of the way)
  93. Depending on your specific application, you will need to source an appropriate flow tube to fill the void of the mass air meter.
  94. Take this time to calibrate the wideband sensor and load the tuner studio program into your laptop.
  95. Refer to our extensive video that explains everything about the tuning program on the computer.
  96. Once you have a good grasp on tuning your vehicle you can start reinstalling the rest of the interior components.

That’s it! We hope that we could provide a very detailed tutorial on this long process that is easy to understand and follow. Check out our video as well!


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About the Video

86-93 Mustang Megasquirt

Check out our YouTube channel for even more tech tips, installation videos, how-tos, and more. The best place to go for anything Mustang related!

Published on 2019-07-11
MegaSquirt: https://latemodelres.to/FoxMegaSquirt
Innovative Wideband: https://latemodelres.to/Wideband
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PRODUCT DESCRIPTION
MegaSquirt PNP2 Standalone ECU Tuner Kit by DIYAutotune.com
Add serious tuning potential to your 1986-1993 5.0 Mustang with MegaSquirts Plug and Play Gen 2 standalone ECU. Designed with the DIY tuner in mind to give your Mustang all the options of a custom engine management system at a fraction of the cost. Easy to install and setup, this standalone ECU comes with a 5.0 HO base maps is pre-loaded to help your engine start on the first turn of the key. With an average install time under 1 hour, this unit installs in your stock ECU's place making it as streamlined and simple as possible. Combined with a USB to Serial adapter and a Innovate MTX-L Digital Wideband Air/Fuel Gauge will taking your tuning to the next level!

Tuning At Your Fingertips
TunerStudio brings MegaSquirt 2, tuning software unmatched by any other aftermarket EFI controllers at any price. The free version of TunerStudio MS, known as TunerStudio MS Lite is hands down the leading MegaSquirt software, it allows you to fully set up and tune any MegaSquirt controller with a more refined and simpler interface than all previous options.

Tuning Hardware and Software Note
Use of the provided USB to Serial Adapter is recommended to interface modern laptops with the MegaSquirt PNP2 serial port.

Innovate MTX-L Digital Wideband Air/Fuel Gauge
Easily datalog and remotely tune with this Innovate MTX-L digital wideband air/fuel ratio gauge! This 100% digital gauge is the only one of it's kind on the market. Utilizing award-winning and patented DirectDigital™ technology, this gauge is faster and more accurate than the common "UEGO" gauges. This reduces wiring and simplifies your installation. The wideband O2 sensor is compatible with all types of fuel including leaded, unleaded, diesel, methanol, and E85.

Key Features and Full Control
- Fully Plug and Play Installation – No wiring required for basic functionality.
- 5.0 HO base maps are pre-loaded to help your engine start on the first turn of the key.
- Real-time tuning and data logging with a laptop connection.
- Supports most aftermarket wideband sensors.
- Uses internal MAP sensor – can be used on both cars with factory MAF or speed density.
- Mounts in the stock location – case is specifically designed to use factory mounting points.

Product Notes
- Scalable to popular larger engine sizes.
- Due to the custom nature of this product, please be sure to read all installation manuals provided. Please visit DIY Autotune for more detailed instructions and technical articles.

Applications
- Fits 1986-1993 Ford 5.0L Mustang

This product is intended for off-road use only, and is not legal for use in emission restrictive states.
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______________________________________________________

Due to factors beyond the control of LMR.com, we cannot guarantee against the improper use or unauthorized modifications of this information. LMR.com assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Use this information at your own risk. LMR.com recommends safe practices when working on vehicles and or with tools seen or implied in this video. Due to factors beyond the control of LMR.com, no information contained in this video shall create any expressed or implied warranty or guarantee of any particular result. Any injury, damage, or loss that may result from improper use of these tools, equipment, or from the information contained in this video is the sole responsibility of the user and not LMR.com.
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Always reference the product page for the most up-to-date pricing and information as this can change at any time.