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Mustang Mass Air Conversion Guide

Created by Jeff Jimenez
Last Updated 12/10/2016

Need help converting your 86-88 Speed Density Mustang over to a mass air system? Check out this guide to help you with your swap!

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FOLLOW: mustang , 79 93 mustang , fox body , tech , engine

With the introduction of the fuel injected V8 in 1986, the 5.0L Mustang was an instant success. It quickly became the "Legend" that we know all too well to this day. Fuel injection added a more efficient and reliable aspect to the 5.0L H.O. It also performed exceedingly well with the addition of common bolt-on items like headers, free flowing exhaust and cold air intake (CAI) systems. Even more power could be had by swapping out the cylinder heads and intake manifold. The problem arose when you wanted to add a performance camshaft or higher flow fuel injectors to really tap into the power potential of these motors. The earlier 86-88 cars used a speed density EFI (Electronic Fuel Injection) system which performed well and served its purpose. The drawback to this system is that modifications to the engine could not alter manifold vacuum or fuel supply in order for it to maintain a good idle quality and not have major surging issues or die when pulling up to a stop light. You could remedy this by having a custom chip burned for your application, but it still made modifying your car more difficult. The reason why is that speed desnsity based its engine calibrations off of fixed tables in the PCM and one of the key inputs was the MAP sensor (manifold absolute pressure) which monitored intake manifold vacuum.

Mustang Mass Air Conversion Guide - Mustang Mass Air Conversion Guide

The answer to this dilemma came in 1989 (1988 in California) with the introduction of the mass air meter, A9L processor/ECU, and swapping out the MAP sensor for a BAP sensor (barometric air pressure). Actually, the MAP and BAP are identical. For it to be MAP, a vacuum line connects the sample port of the sensor to an intake vacuum port. To be BAP, the sample port is left open to the atmosphere. With these additions, Mustang enthusiasts were now able to add considerably more aggressive cam profiles to their cars as well as easily compensate for high flow fuel injectors and everything took off from there. Adding a mass air system to the earlier 86-88 5.0L Stang will allow you to improve the overall performance and functionality of your Mustang. Here at LMR.com, we understand the benefits of converting 86-88 Mustangs over to mass air. We offer a full selection of mass air conversion parts to help you with your swap. We carry wiring harness, mass air meters, and intakes.

Our conversion wiring harness allows you to tap into your existing harness. Reducing the need to remove and replace your factory one. We have a full selection of mass air meters available in multiple different sizes and fuel injector calibrations to fit your performance needs. We also have a full selection of cold air intakes to fit your new mass air meter. The only part left to source is a A9L processor “PCM”. Junkyards and Stang salvage yards are going to be your best source for these. If you have any questions about this conversion give any of our Mustang technicians a call!!

What Parts Are Needed For A Fox Body Mustang Mass Air Conversion?

  1. Mass Air Conversion Wiring Harness (PMA-EMAWH See Below)
  2. Computer/ECU
    • Manual Transmission – A9L Code ECU/Computer
    • Automatic Transmission – A9P Code ECU/Computer
  3. Mass Air Meter – See Below
  4. Cold Air Intake – See Below