mass air flow

Discussion in 'Fox 5.0 Mustang Tech' started by powermaxx, Mar 18, 2006.

  1. i am going to put a mass air flow computer and sensor on my speed density 5.0.

    what are the best components to use?
    91 mustang computer (5.0) with an aod and stock mass air flow sensor
    95 mustang computer (5.0) with the aod and a stock mass air flow sensor

    does a 95 gt have a larger mass air flow sensor? what type of injectors is it calaborated for?

    this is all for a 89 5.0 truck
  2. I don't know what the size was for a 95 GT, but the injectors shouldn't have changed.

    I think the computer may be less aggressive than the '91s, but I'm just going off of something (basically a rumor) I'd heard years ago.

  3. I've been using the same C&L 73 meter for about 3 years. Still works great even with all the mods I've done.
  4. is a 95 mass air bigger than a 91?
    if so will it work with old 91 computer?
  5. You will need a meter that is calibrated for that computer or has the correct sample tube for the injectors you will be using. I would recommend getting an aftermarket meter that is compatible with that computer. In my opinion its easier to just pay for a new meter than trying to find factory stuff that will work together. And factory meters aren't especially generous with the airflow either.
  6. Also use the earlier computer, they have more aggressive timing tables for better performance. I dont know if the '95 is OBD II, but if it is, I'd avoid it.
  7. so i should go with the 91 computer and a aftermarket 70mm?

    which are the best ones
  8. The 95 computer won't mate electrically to a 93 or earlier computer harness - the pin arrangement is different.

    As for the 94-95 Mustang GT MAF - $40-$100. It is 70 MM instead of the stock 55 MM on regular stangs built prior to 94. It uses a slip on duct on the side that goes to the throttle body and a 4 bolt flange on the other. You need a $25-$35 flange adapter from Pro-M to fit the stock slip on air ducting that goes to the air box. Wiring plugs right in with no changes. I am running one, so I know firsthand that it works good.

    All the Mass Air computers from 89-93 are interchangeable with a few exceptions.You can also use an auto computer in a manual... but not a manual comp in an auto. The odd duck is the 93 Cobra computer, labled X3Z which is interally calibrated for 24 lb injectors. Try and avoid it if you can.

    Look for the A9L sticker on the back cover for a 5 speed that matches your requirements. Example: E9ZF 12A650 AA" with the A9L code.

    A9L - 89-93 5.0L Mustang 5-spd
    A3M - 93 5.0L Mustang 5-spd
    A3M1 - 93 5.0L Mustang 5-spd
    X3Z - 93 5.0L Cobra 5-spd
    A9P - 89-93 5.0L Mustang Auto
    A9S - 88-93 5.0L Mustang California
    C3W - 89-93 5.0L Mustang Auto
    DA1 - 87 5.0L Mustang 5-spd
    J4J1 - 94-95 5.0L SVT Cobra 5-spd
    T4M0 - 94-95 5.0L GT Vert 5-spd
    U4P0 - 94-95 5.0L GT Auto
    W4H0 - 94-95 5.0L GT
    ZA0 - 95 Cobra R
    D9S - Lincoln LSC

    Copied From bbunt302

    Just for reference, here's a list of all the compatible years:

    89 harness should work for 86-89 as long as you're using mass air.
    90 harness will only work in a 90. (B/c of air bags and dual dash connectors)
    91 through early 92 harnesses should be compatible (single dash connector, fuel pump relay under driver's seat)
    Late 92 through 93 harnesses should be compatible (single dash connector, fuel pump relay under the hood)

    MASS air conversion instructions from FREE
    A9L (5 Speed) computer from junkyard $100-$150
    A9P (Auto or in a pinch, 5 Speed) computer from junkyard $100-$150
    70MM MAF from 94-95 Mustang GT - $40-$70
    MASS Air wiring harness kit $30-$85

    The whole thing is probably less than $300 using junkyard parts.

    A9L computers are 5 speed only
    A9P computers are automatic, but will work with a 5 speed.

    Conversion Harness kits & parts
  9. so i can use a 91 mustang computer in my 89 truck and a 70mm meter?
    does a computer need to be caleberated for 70mm meter?
  10. how do you caleberate a computer to 70mm mass air flow and 24lb injectors?
  11. You don't. You calibrate the meter to use the stock EEC setting along with 24 lb injectors.

    In other words (put simply): You calibrate the meter to the injectors. Going to 24s will not require further modifaction the EEC.
  12. so if i buy 24lb injectors and 70mm mass air what do i have to do to make it work properly?
  13. You would buy a meter that is calibrated for use with an A9L and 24 lb injectors. There's a link in my sig for a company that has these.
  14. im new to this mass air stuff so i dont rilly know what im dooing.

    a little help would be apreciated.
  15. The aftermarket MAF's trick the computer so that you can use larger injectors.

    The 70 MM's OEM Ford MAF's are 19 LB units. The 94-95 Mustang GT is a 70 MM that is a direct swap if you get an adapter to mate the bolt on flange mount to the rubber slip tube ducting. You don't change any wiring or do anything with the computer except to disconnect the battery for 10-20 minutes so that it re-learns the settings.

    The stock 19 LB tan/orange injectors are good to 300 flywheel HP. Don't go with 24 LB injectors unless you are running aftermarket heads/intake/cam (H/C/I) or they are sitting in your garage waiting to be installed. They just aren't needed on a stock engine.
  16. Fox Fuel Injection overview

    Let's list the basic components:

    Computer/EEC/ECU: (A9L, A3M, A3M1, D3D1, X3Z, S0Z, A9M, A9P, C3W, C3W1, A9S, 8LD)
    Applications aren't real important for this discussion and we'll be concerned with the A9L, A9P, and A9M for now.


    EEC/Fuel Injection Harness:

    Mass Air Meter: (these come in all shapes, sizes, and calibrations)

    Fuel Injectors: (Sizes rage from 19lb/hr to 55lb/hr in low impedance form)

    Low impedance injectors are generally what we use and are what our fuel injector systems are setup to use. Really High HP applications may require larger than 55lb/hr injectors. That's where the high impedance injectors come in. Additional hardware is required to run these injectors but it's not important to this discussion.

    Our fuel injection system in OEM form uses an EEC, Mass air meter, Harness, and injectors to accomplish fuel metering and control delivery. The EEC is programmed to use Ford's Mass air meter, and 19lb/hr injectors to deliver the appropriate amount of fuel for the stock engine to make power all the way through it's usable rpm range. It juut so happens that 19lb/hr injectors are small enough to offer GREAT drivability and are also larger than what is required to support the HP from a stock 5.0 HO.

    Elevated HP levels often require larger fuel injectors. There are a few ways this can be tackled.

    The first is most popular and generally the least inexpensive:
    Changing the mass air meter. A "calibrated" mass air meter fools the EEC into thinking it's running an OEM meter and stock injectors. These meters are calibrated to give the EEC a specific output signal to compensate for larger injectors by "lying" to the EEC so that it meters injector pulsewidth to meet power production demands of the motor. This typically works great for injectors up to 36lbs/hr. Injectors larger than that tend to differ too much in size for the OEM fuel ramps in the EEC to be efficient or work very well. 42 lb injectors and larger usually require modification to the EEC program in order to function efficiently.

    The second method is a programmable ECU or EEC tuner:
    These modify the actual EEC programming. Some give you the abilty to load the transfer curve for the mass air meter to the EEC then let you specify an injector size. Others allow you to simply add or subract fuel at given loads and RPM. This latter type (add/subtract) still requires a "calibrated" meter. Either way, this second method allows allot more control and tunability and allows you to tailor your fuel delivery to meet the demands of your modifications.

    When a meter is said to be calibrated for X size injector, it's an oversimplified, general statement. The meter is not actually calibrated for a specific sized injector. The OEM meter is not calibrated for 19lb injectors (regardless of what many people think). Instead, the computer is programmed to meter the proper fuel for a given meter signal and specific sized injector. these "calibrated" meters are COMPUTER and INJECTOR SIZE specific, not just injector specific. Their signal putouts are modified so that the EEC's OEM programming coincides with the required injector pulsewidth. Injectors larger than 36s are often a problem because the EEC's lack of ability to trim differences in excess of a set tolerance. Imagine a computer that's programmed to open a 19 lb injector for .5 seconds for a postion stroke holding a 42 lb injector open for the same stroke. The more power you produce and the higher yougo into the RPM range, the wider the gap gets between the amount of fuel the EEC "thinks" it's putting out and the amount of fuel that's actually being sprayed into the cylinder. The minimum and maximum duration for a given injector also varies greatly. the larger the differences are in injector size over stock, the more trouble you'll have with trying to adjust without modifying the EEC.

    I'm sure I've left something out.... If so, ask more questions. There's a few folks on this board that are awesome tuners and know this stuff backwards and front. Michael Yount, Hissin50, TMOSS, and JRichker, are a few. There are others that have more specific knowledge about particular EEC Tuners or Meters (because they run them).

    Good Luck

    Attached Files:

  17. i am converting my sd truck to mass air there is a good article on fordmuscle about this but what am i supposed to do with the harness?
    and what type of ford trucks have 24lb injectors?
  18. Visit this site:

    They will have you covered for pretty much any mass air conversion need you may have. I purchased a conversion harness from them and was very pleased with the quality and good instructions.
  19. how do i know if a mass air meter is caleberated for 24lb injectors?

    do i change my injector harness?