Mass Air Computer Rebuild Service

Suspecting a bad ECU? Let us rebuild your computer for you!


Ship us your computer and we will fully inspect it, bench test it with our custom equipment, rebuild it, test it with our monitor, and install it in a running Fox-Body for quality control. This service comes with a one-year replacement warranty provided the seal is not broken and a chip is not added. Matt from the YouTube channel GearHead704 did a video about our rebuild service and you can view that by clicking here.
We are not able to diagnose computer issues prior to receiving your computer. If you need assistance determining whether your computer is not functioning properly, see our ECU testing service below.

Shipping Instructions and Tips


Ship to:

Fox Mustang Restoration
Re: Computer Rebuilds
105 Pine Forest Rd
Locust, NC 28097
*please do NOT package your computer in bubble wrap or other plastic packing material - this can hold a static charge and further damage your computer*

Include in the package:

Return shipping address
Phone Number
ECU Rebuild -or- Testing Service

ECU Rebuild Service - $225


Our rebuild service includes a visual inspection, a processor bench test, new capacitors and repairs to any visual damage we see. From there we will test the computer in our car with our monitor to ensure that each pin of the connector is testing within spec. Sometimes we find out through testing that there are other bad components that don’t have a visual symptom - so some computers may take a little longer and need a second round of repairs. We will contact you to let you know that we received your computer, then we will put it in line for inspection. If it is rebuildable (most of them are), we will then rebuild it and contact you again for payment prior to shipping it back to you. Return shipping is included in the service price.
Please note that the car that we test our computers in is a daily driver and may sometimes not be available for testing. Usually the car is here at the shop at least once a week available for us to test computers in.

Not sure the problem is your computer? We offer ECU testing in addition to our rebuild service!


ECU Testing Service - $60

Upon request, we can put your computer through our usual post-rebuild testing procedures before starting the repairs.
This includes a visual inspection, a standard processor bench test as well as an in car test with our monitor. Please be sure to specify in your contact info if you just want us to test your computer. We will contact you to let you know that we received your computer, then we will put it in line for inspection and testing. Return shipping is included in the service price. We’ll contact you for payment once we’ve tested the computer.
Please fill out this Google Form with the matching information and a tracking number of the computer being sent to us.
*Rebuilds are typically done on Mondays, testing on Wednesdays, and return shipping on Fridays.*
Occasionally, we have rebuilt computers available for purchase for $575. These are rebuilt in the same manner described above and carry the same warranty. If we have any in stock they will be listed (insert link to computer core search on website). If you can’t find the computer you’re looking for on our website, feel free to call (704.888.1278) or email ( us! We may have a core that has not been rebuilt yet.
The A9L computers were originally used in the 5.0 5-speed cars from 1989-93, but if you are doing a mass air conversion on a 1986-88 you will also need an A9L. We can rebuild any 1988-93 computer, regardless of the designation, A9P, A3M, C3W.

Fox Mustang Restoration wants your old computers!

Just ship us your old A9L or A9P (they do not need to be in working condition) and we will pay $150 for A9L, A9P, A3M, C3W’s upon passing our preliminary bench test. *
*Please include in your information that this computer is a core for sale*
If you need more information or have any questions, please email us at or call 704.888.1278.