Will Lightning MAF with PMS?

Discussion in '1994 - 1995 Specific Tech' started by 95 stanger, Apr 4, 2006.


  1. 95 stanger

    95 stanger New Member

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    I just finished installing a Vortech S-Trim, 42lbs. injectors and 90MM Lightning MAF on mostly stock engine other than throttle body and Performer intake. I just got my PMS and faxed the sheet to AFMS to get the intial tune. I got back a sheet from Anderson saying that my MAF wont work and I need to get one calibrated for computer and injectors. Is anyone else running a similiar combo with a Lightning MAF? I really don't want to buy another MAF if I don't need to.
    #1
  2. blksn955.o

    blksn955.o Founding Member

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    I dont have a PMS or know too much about it.

    However, this seemed to be an issue with the PMS as far as no access to the maftransfer to tune. That is one thing I realy didnt like about the PMS and our cars.

    not knocking you just trying to get a answer to why you dont have access to that area?
    #2
  3. nmcgrawj

    nmcgrawj Advanced Member

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    You can access it i believe with the programs avail. for the PMS. The PMS itself does not go into the "brains" of the EEC. It just modifies what signals come out of it...or if any at all(stand alone). Thats how they keep it so simple, easy, and effective to use. Now buy those programs for a laptop and u just walked into the technical world of the tweecer fellas.

    But it was my thinking that a maf is not calibrated for a computer...its calibrated for injectors. So if its calibrated for 42's...and thats what u run, i dont see why it wouldnt work.

    Go to stangtuning.com and search/ask over there. Brian from AFM is on the boards a lot. Also Gary and Troy with a bunch of others know their stuff. They will be able to give u a definate answer and a detailed explaination why.

    Do us a favor and post back when u find out.
    #3
  4. final5-0

    final5-0 Mustang Master

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    Here is some basic stuff to remember about Mafs that may be of some help

    When you see the words calibrated or sample tube .....

    Those words are used by aftermarket maf manufactures to describe their particular method of cheating or lieing to the pcm about air flow. This is done with the intent to allow you to use larger inj's and their maf without needing a tune.

    Works kinda sorta good with Fox Stangs
    but
    rarely works with the same amount of effectiveness on our Stangs

    When you talk about oem mafs like our stocker or say a Lightning maf, they are not calibrated in any way whatsoever like aftermarket mafs. The range of air flow they can accurately report is matched by the values in the pcm. This is the very reason Ford used the exact same maf in the GT & Cobra. The air flow requirements of the Cobra were not beyond what the GT maf could accurately report to the pcm.

    NO cheating or lieing is used with oem mafs

    btw ... The Cobra fuel requirements were greater than what the 19lb GT inj's could supply and Ford told the Cobra pcm that 24lb inj's were being used. This is ABSOLUTELY NOT any kind of calibration thing or as some say on these forums "Ford did the calibration in the computer to make the GT maf and 24lb inj's work together" ...... the whole point of what we are talking about here can be said like this ......

    Inj's don't have anything to do with Mafs
    Mafs are all about air flow

    anyway ...... back to the main topic

    It is true, a Lightning came with a 90mm maf and 42lb inj's
    AND
    Ford put the values in the Lightning pcm to reflect those parts

    Having said all that

    Doesn't it make sense that we CAN NOT put maf/inj's from a Lightning on our car when our pcm thinks we got the stock 94-95 maf/inj's. This is the reason you always see peeps being told you gotta get a tune if you try to use the Lightning maf.

    Don't konw if any of this stuff helps :shrug:
    but
    I tried :)

    Grady
    #4
  5. nmcgrawj

    nmcgrawj Advanced Member

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    That makes perfect sense grady. My confusion is that the PMS should be able to tune around the problems that would arise....maybe the differences would be too great or something :shrug:

    But with AFM saying getting a maf calibrated for your computer and injectors, isnt that saying getting one that is calibrated for 19lb injectors since thats what our computer thinks is there? Or does it mean to get a maf that knows the computer expects 19's but it needs to expect 42's? So i guess, what would the difference in performance be from a Pro-m for 42's and a lightning for 42's?
    #5
  6. final5-0

    final5-0 Mustang Master

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    I'll hit the high points and then I'm gonna give you some info that explains it better than I can.

    Form the pcm's view point, it can only take 0 to 5 volts for its maf input. Makes no difference if we are talkin about a little stocker Stang or a blown Lightning.

    If you put a Lightning maf on a stock Stang, the maf would only send something like say maybe 2 to 2.5 volts to the pcm as the little stocker can't generate near the air flow as the bad boy Lightning.

    The voltage range can never change don't you see :)

    The whole maf/inj thing can be a challenge to grasp :bang: so here is some info that makes more sense than me :rlaugh:

    Basic Maf Theory & ProM's "Cheat" Method Explained


    Assumptions for this document are that you own a TwEECer or EEC-TUNER
    and that you are running larger than stock injectors and/or Mass Air Flow
    meter (MAF).

    First lets start with a little theory. The way the ford EEC series
    processors determine the amount of fuel and calculate load values is by
    measuring the amount of air that is flowing into the engine via the Mass
    Air Flow (MAF) sensor. The MAF sensor works by heating a wire inside the
    sensor. As air flows past the wire it cools the wire. Depending on how
    much the wire cools and the radius of the MAF sensor you can calculate the
    physical volume of air flowing through the sensor. This measurement is
    sent to the EEC processor as a voltage reading between 0 and 5 volts.

    The EEC has a 30 point table pre-programmed into it that references a
    voltage reading to an amount of air in kilograms per hour (KG/HR). For
    simplicity lets pretend it is only a 5 point table and use simple round
    numbers to make calculations easier. For example:

    5 volts = 1000kg/hr
    4 volts = 700kg/hr
    3 volts = 500kg/hr
    2 volts = 350kg/hr
    1 volts = 250kg/hr

    The way the EEC works is to reference the voltage signal to a row in the
    table. If the voltage falls between two readings it calculates a value
    using the surrounding numbers. So if the MAF was sending a signal of 3
    volts you would have 500 kg/hr of air flowing into the engine. If the MAF
    was sending a signal of 2.5 volts you may expect 440 kg/hr (the scale is
    weighted with larger increments in the higher voltage range).

    The EEC then uses this table to calculate the pulse width for each
    injector to supply the proper amount of fuel to feed the measured air.
    This calculation is based on the values in LOW_INJECTOR_SLOPE and
    HIGH_INJECTOR_SLOPE (more on these settings later). For now assume that
    both are set to 20 to represent a 20lb injector.

    Now lets assume you ordered a new MAF meter from Pro-M and had it
    calibrated for 40lb injectors (remember, these are all made up numbers).
    You installed a fresh set of 40lb injectors and bolt on the meter. How
    does the meter make the 40# injectors work with the stock programming? It
    does this by reducing the voltage from the MAF meter to represent a
    physical volume of air equal to the factory injector size divided by the
    new injector size (in this example 20/40 or ½). NOTE: It is NOT reducing
    the voltage by this percentage, this is very important to understand. The
    reduction in voltage is precisely engineered to make the EEC believe it is
    receiving intake air - reduced by this percentage. This means that if
    1000 kg/hr of air is actually flowing through the meter it will signal the
    EEC with 3 volts (from our table above). This tells the EEC that 500 kg/hr
    of air is flowing into the engine and the EEC opens the injectors (that it
    still thinks are 20# injectors) for long enough to feed 500 kg/hr of air.
    Since the injectors are actually bigger (twice in this case) the amount of
    fuel injected is actually proper for the 1000 kg/hr that is flowing
    through the meter.

    You can also do the math in reverse. At the same voltage reading from the
    stock MAF and the new MAF your actual airflow will be new injectors
    size/old injector size (in our example 40/20 or 2). So, if the voltage is
    3 volts from the new MAF which corresponds to 500 kg/hr of airflow when
    you look at the stock transfer table at 3 volts you would see 250 kg/hr of
    airflow.

    This works fine for most tuning needs but does mess with other
    calculations in the EEC like load values. You also don’t have the ability
    to accurately scale fuel unless your MAF table accurately represents the
    meter and if you plan on data logging it is nice to have the log show you
    actual airflow.

    For all these reasons and more it is recommended you tell
    your EEC what is actually going on by entering actual flow numbers and
    actual injector sizes using the TwEECer or EEC-Tuner.


    Grady
    #6
  7. nmcgrawj

    nmcgrawj Advanced Member

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    I gotcha grady....i did some searching over on stangtuning. Found a couple useful threads....

    http://stangtuning.com/showthread.php?t=2455&highlight=lightning maf
    http://stangtuning.com/showthread.php?t=3067&highlight=lightning maf

    The pms can modify the transfer functions, but only when its under "standalone" http://www.stangtuning.com/showthread.php?t=2455&highlight=maf transfer


    In the threads, a guy had a Pro-M bullet MAF(77 i think?) and 30lb injectors. He wanted to get 42's so he can run a bigger shot of nitrous, so he bought 42lb injectors and a LMAF. Then he found out the LMAF wont work without modifying the TF, so then he was informed to use his 42lb injectors, his old bullet maf calibrated for 30's, and to use the Global Fuel function in the PMS to dial back the extra fuel. Cause he only needs the extra fuel for the juice.

    I also found out that the lightning calibration is equal to a 30lb calibration for a 96-97 Mustang GT. I never knew that....

    Good discussion fellas :nice:
    #7
  8. final5-0

    final5-0 Mustang Master

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    As always Nate .......... its good to share info as we all can learn from it :banana:

    If you will allow me to be a bit bold and make an observation about you and your attitude you seem to put across on this forum :hail2: :cheers:

    I do appreciate your willingness :)shrug: is that a word :rlaugh:) to get involved in discussions where everything is not known

    AND

    You seem to have the confidence to ask questions

    OR if you will

    You don't seem to be afraid to let it be made known you don't always have an understanding about various things.

    One of the great things about 94-95 :SNSign: is when peeps ask a question ... they may get told to search out the answer if it has been covered many times before

    but

    for the most part, I'd like to think peeps feel free to get involved without fear of being made fun of or having to deal with some sort of intimidation thing from other members.

    I know I myself certainly do not understand a lot of things about our hobby

    but

    if more peeps would get more involved like you do in these discussions :nice:

    I could learn more :banana:

    I guess that shows that my motivation for paying you a compliment is purely selfish :rlaugh:

    Grady
    #8
  9. nmcgrawj

    nmcgrawj Advanced Member

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    lol haha thanks man, nice to hear that coming from a guy like you. Your writing style always cracks me up....its short and to the point and its much easier to read than long paragraphs. Plus the perfect use of smilies in the right places...it gives a good laugh :lol:

    I dont have a problem speaking up...even if im purely guessing and completely wrong. Its not a contest. It wont change anything except my knowledge and others reading knowledge of the subject. Like in that Flopro's turbo thread when we were discussing his boost problem...i "thought" i knew what was wrong, was i confident? hell no :lol: i just took a stab at it. And what do ya know...i came out right :banana:

    So yea, its always been my nature to ask questions to see how things work. A bigger part of doing that, especially like with you is there are guys who are willing to explain it in a way thats understandable. And its not questions like "what rear gear is best" or "what do i need to do for 500hp" kinda questions. They are usually fairly detailed and technical. Searching could work in most cases, but sometimes active conversation answers the question better, giving a better understanding of the subject. And with this tuning section being so new...there is really nothing to search for. Yea, we could just run over to stangtuning and not talk about it here but then u take away from the point of this section:SNSign:
    #9
  10. final5-0

    final5-0 Mustang Master

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    I kinda thought you might feel that way :cheers:

    If we keep this stuff up ............

    You will know how to tweec
    and
    I'll know how to pms .......................

    on second thought ...................................

    Well .......... you know what I mean :D

    Grady
    #10
  11. final5-0

    final5-0 Mustang Master

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    Is it proper forum etiquette to quote one's self :shrug:

    I'm gonna do it anyway :D


    Now that Don is starting to cruise over here from time to time

    Maybe we can twist his arm a bit and learn some juicy tid bits about self tuning SCT style :banana:

    Grady
    #11
  12. Starman

    Starman New Member

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    for what its worth....

    I run a 90mm Lightning MAF and 42lb injectors. I don't run a PMS, but a Speedbrain. I tell it that I'm running 42lb injectors and I use the '03 Cobra MAF transfer function from the twEECer software/boards. I did do a little tweaking of my own to the transfer function using a wideband O2.

    I tried the Lightning transfer function but it ran super rich, probably because they're 5.4l ??
    #12
  13. 95 stanger

    95 stanger New Member

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    Thank you for your help everyone. :hail2: I guess I didn't research enough before I bought the Lightning MAF and the PMS. Anyway, I have a new 90mm Lightning MAF and pigtail for our cars for sale if anyone is interested.:D
    #13

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