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Thread: Mass Air added, hesitation off the line

  1. #1
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    Default Mass Air added, hesitation off the line

    88 bird with 5.0L with explorer parts & AOD.

    Vinnie Tbird Mass air computer which was supposed to be an A9P equal, not sure what brand it is,,, says its a Reman.

    Mass meter & injectors from MK8 (blue top injectors)



    We followed the coolcats instructions and got the mass air upgrade done to my sons silver 88bird., he's in for the week and we have a list of things to do and mass air is one.

    No engine light coming on so i assume no codes.
    Difference from SD to Mass Air changes:
    -off the line there is a significant hesitation off the line.
    Fuel presure is fine, fuel pump was upgraded to something around 160LPH year before last.

    Anyone have hesitation on Mass air upgrade and what did you find to be causing it?

    could be a dirty mass air sensor?

    where do we start without any check engine light , meaning no codes ????
    Map sensor vac line is unplugged and capped off.


    we are out working on it now,, 304 772 3411 if you just want to tell us verbally..

    thanks!!

    scott & mason cassity

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    Quote Originally Posted by jcassity View Post

    Mass meter & injectors from MK8 (blue top injectors)

    So the injectors and MAF are from a Mark VIII? If so you CAN NOT USE THE MARK VIII MAF WITHOUT A TUNE. IT IS NOT CALIBRATED TO THE INJECTORS. Injector calibration is done inside the Ford EEC. So to run 24lb injectors on a stock A9P style processor (set up for 19lb injectors) you have two options:

    1. Tune the computer using a tuner, like Moates Quarterhorse: http://www.moates.net/quarterhorse-for-fords-p-199.html

    2. Use an aftermarket MAF calibrated to the injector size. It "tricks" the computer so you can run 24lb injectors with a computer programmed for 19lb injectors: https://lmr.com/item/PMA-12579AE/198...Meter-For-24Lb
    Last edited by thunderjet302; 08-14-2017 at 06:45 PM.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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    What he said. Everything really needs to be on the same page. Moates is definitely good advise if you plan on adding alot of power or changing parameters later on, I wish I went that route. That said, the quick and easy aftermarket MAF does work well.
    2008 Chevrolet Cobalt Sport
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    1988 Thunderbird LX - sold
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    Actually option 3: stick the 19lb injectors back in and run a stock 89-93 Mustang MAF. Then after you either get a tuner (harder option) or calibrated MAF (easier option) put the 24lb injectors back in.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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    Quote Originally Posted by thunderjet302 View Post
    Actually option 3: stick the 19lb injectors back in and run a stock 89-93 Mustang MAF. Then after you either get a tuner (harder option) or calibrated MAF (easier option) put the 24lb injectors back in.
    You must have been reading my mind. Used MAF sensors can often be found on craigslist when people upgrade to turbo's or blowers.
    1986 Thunderbird Elan 5.0 EFI AOD, 3.73:1 SN95 rear, 17" Mustang Bullitts w/Firestone WO Indy 500's. Future plan: 349 stroker, C9 block, forged dish pistons, Scat 9000 crank, 4340 I beam rods, ARP head/main studs, ported explorer intake, 1.72 CC RR, Vortech V2 supercharger, Mr. Freeze Meth Inj, intercooler, TFS 190 11R CNC heads (66CC), BBK shorties with 2.5" duals, 4R70W Transmission, Taurus fan.

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    in your bold print,, i will reword so pls tell me if this is what you meant.....
    you said
    " IT IS NOT CALIBRATED TO THE INJECTORS"

    What i think i take away is " The EEC is not calibrated to the injectors"

    correct?

    Reading the coolcats instructions, there wasnt a warning about the computer matching the maf.
    I was under the impression you need the maf and matching injectors on a car then hook it up to a maf ready computer.

    Im thinking we back down to speed density HO and add the PP intake and stay out of this maf thing. nobody's life seems to be that easy when they go maf anyway.

    oddly the car runs really good.


    I dont know what you mean by "get a calibrated maf",, thought we had that.

    do you mean "get a special maf for 24lb injectors made to trick the eec into thinking they are actually 19lb?

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    Quote Originally Posted by jcassity View Post
    I dont know what you mean by "get a calibrated maf",, thought we had that.

    do you mean "get a special maf for 24lb injectors made to trick the eec into thinking they are actually 19lb?
    That's what's required...






    My other rides (that actually do run & drive)

    1969 Fairlane Cobra 428CJ 4-Speed << New 49th Birthday Picture

    1972 Comet GT - 306 C4

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    from my other stock pile of parts i think i have a calibrated maf for EECIV to run 24lb injectors.. this extra Maf is intended to run on my younger son's (chance) 331 .030 over coug motor but i suppose we could borrow it over to my oldest son "mason" to see if it works.

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    Quote Originally Posted by jcassity View Post
    in your bold print,, i will reword so pls tell me if this is what you meant.....
    you said
    " IT IS NOT CALIBRATED TO THE INJECTORS"

    What i think i take away is " The EEC is not calibrated to the injectors"

    correct?
    No the EEC is "calibrated" to the injectors. An A9P is set up to fire 19lb injectors. No factory Ford MAF is calibrated to an injector size. The same stock MAF from an 89 to 93 5.0 Mustang used with 19lb injectors is also used in 89 to 93 Thunderbird SCs with a supercharged 3.8 V6 and 30lb injectors.

    All the computer knows is the size of the stock injectors and how much air is flowing through the MAF at certain voltage points (i.e. the MAFs transfer function). By putting 24lb injectors and the MAF from a Mark VIII in the EEC is having two issues. First the transfer function of the Mark VIII's MAF is no where close to the stock MAF. The EEC has no idea what to do with the information it is receiving. Second it's dumping too much fuel into the engine, since firing a 24lb injector for the same amount of time as a 19lb injector is going to provide more fuel. Hence why your son's car is running like crap.

    So what an aftermarket MAF that's "calibrated" does is lie to the computer. An aftermarket MAF calibrated for 24lb injectors in a 1990 Mustang that came with 19lb injectors stock outputs a voltage signal to the EEC that is19/24 of the stock MAF. This allows the computer to fire the larger injectors without overfueling.

    Aftermarket MAF calibration is important without a tune. If you're not sure what setup the MAF you have is calibrated for I would suggest buying a new one that is set up for your intake system. A 24lb calibrated MAF for a 89 to 93 5.0 Mustang will not work with 24lb injectors in a 1998 Mustang. The MAF also has to be setup for the stock airbox, a conical filter clamped to the end of the MAF, or a bend in front of the MAF. If you don't know what MAF you have in your 331 parts pile don't use it.

    To run the 24lb injectors grab a stock airbox and the MAF I linked. I bet it solves your problem for good.
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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