75mm mass air flow meter installed,,wont idle?

Discussion in 'Fox 5.0 Mustang Tech' started by willys1, Jan 31, 2004.


  1. willys1

    willys1 Banned

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    I just installed a 75mm mass air (Pro M) meter,when its cold,it wont idle, it will just stall out!And before I installed it,it had a slight surge(about 75 rpm) now its like 150 rpm.Could sure use some suggestions!!
  2. 5.0Droptop

    5.0Droptop ...all those nights we shared, and you're a dude??

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  3. willys1

    willys1 Banned

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    Its not the idle,once it is warm it idles fine.But when you start it up when its cold it goes up to 1800rpm for a split second,like normal,but on the way down it doesnt stop ,it stalls out?It ran great before I installed the new flow meter.
  4. bmo37

    bmo37 Founding Member

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    first u stated there was a surge before the install and your next post you state the car ran great before the install which is it. A few questions is the maf new, is it calibrated for your injectors? if its not new try cleaning the sensor wires with electrical circuit cleaner to remove oil and dirt from sensor, did you try rotating the sensor (if you have a fender mout cold air kit or any bend in front of the meter than you air path may be directed other than straight on, try disconnecting the battery for 20mins and letting your cars computer reset.

    if none of that stuff works you might of had a problem before you installed the maf and its installation made the problem worse, check for vaccum leaks on the tree, tubing and near the manifold. Another culprit is the iac sensor.
  5. 5.0Droptop

    5.0Droptop ...all those nights we shared, and you're a dude??

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    Did you reset the eec after you instaled the new maf?
  6. willys1

    willys1 Banned

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    **By reseting the eec you mean disconnect the battery? Yes I did that.I just took it out for a drive,it really runs like *****.Even when normal cruising,it bucks and hesitates.WTF?
  7. willys1

    willys1 Banned

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    It would surge once in a while,it wasnt constant.It ran mint before.When I started (Totally cold,overnight) it up it would go to 1800rpm for a moment,then go back down to 1100 for about 25 seconds then down to idle.Now it goes up to 1800,and rite down to zero!! And when driving it,it hesitates,and I dont feel any power increase,it was the stock maf
  8. PRO50SC

    PRO50SC New Member

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    In my opinion the Pro M is a POS. I had the exact same problem. Not only would the car run like crap when it was cold but it also pinged like crazy when it was warm. I put my stock unit back on and no problem. I have read a lot of threads where people have had the same problem. I'm sending mine back. I called their tech line and the guy gave me a bunch of stuff to check, that wasn't any help either. :notnice: :notnice: :notnice:
  9. sixty9boss302

    sixty9boss302 Founding Member

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    What size injectors are your running? Im sure this sounds like a stupid question but u might not have the right MAM thats calibrated for your injectors. Next i would check your IAC and then check the voltage of you TPS. With the car all warmed up you said that it idles correctly right? So maybe with the car warm you should try reseting your idle and then check your TPS....just a couple things...might work!
  10. 88GTStreetRod

    88GTStreetRod Member

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    I am having the exact same problem. I did not change my Mass air meter, but I put on new heads and intake. Once re-installed, I have the idle surge at times as well as the bucking at cruising speeds. I have changed everything from the MSD and coil to new throtle body, rotors, wires, plugs, etc.. Everything is new except for the Mass air censor. I have a cobra mass air and have 24lb injectors. My Mass air is a 19lbs mass air. It worked fine before the head and intake swap . I am thinking there is too much air or not enough with the 19lbs 75mm mass air. I was told by my speed shop that that with the cobra mass air you have to always have one less mass air meter then injectors, hence... 24lbs injectors and 19lbs mass air.

    Any Ideas?



  11. willys1

    willys1 Banned

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    Yup,Its calibrated to my injectors.The motor is 100% stock except headers(shorties).This is such an easy bolt on,why am I having so much trouble
  12. PRO50SC

    PRO50SC New Member

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    Because it's a POS!!!
  13. willys1

    willys1 Banned

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    HUH?
  14. willys1

    willys1 Banned

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    Yeah DUDE,mine pings too--WTF!!!
  15. willys1

    willys1 Banned

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    Then give me some advice on a good brand maf???
  16. bmo37

    bmo37 Founding Member

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    Pro-m is probably the best one out there, for non moddied cars c&l will work if you plan on staying pretty much stock.
  17. 5.0Droptop

    5.0Droptop ...all those nights we shared, and you're a dude??

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    I have a Pro M and it works perfect. I have 24 # calibration for 24# injectors Never a problem.
  18. PRO50SC

    PRO50SC New Member

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    Piece Of *****
  19. PRO50SC

    PRO50SC New Member

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    You must be one of the lucky ones!
  20. 5.0Droptop

    5.0Droptop ...all those nights we shared, and you're a dude??

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    You need to have a 24# meter with 24# injectors. A Cobra maf is a 19# maf and it will not work with 24# injs unless you have the cobra eec..I already went thru this with the FMS tech line and they told me if I want 24# injs I should Buy a Pro m. MAF


    For those who are saying PRO M is Junk I think maybe either someone lied to you about the calibration or something because Pro M is about the Best.

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