What is your MAF voltage at idle????

Discussion in '1994 - 1995 Specific Tech' started by JJ95GTID, May 9, 2008.


  1. JJ95GTID

    JJ95GTID Active Member

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    Just want to know what your MAF voltage is at idle.

    Trying to tune my car with an IST Air Adjuster, idle screw on the throttlebody and a wideband A/F sensor.

    Before the Air Adjuster my car would die at idle and when coming to a stop. Also, at no load/cruising speeds the car would studder really bad. So, the car was running way too lean apparently.

    Okay, so now the car can idle with this adjuster on there but I am not sure about the MAF voltage. And, at idle, the wideband is pegged at 22.4 A/F ratio. Should the car run super lean at idle?:shrug:

    At cruising speeds the car doesn't studder anymore but it seems to hang the rpms at speed for a while before it decides to drop the rpms. Too rich now?:shrug:

    When lightly accelerating the A/F goes between 13.x-15.x.

    At WOT the A/F goes down to 10.9 which also seems good.
     
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  2. The O.G.

    The O.G. Member

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    my idle volts .74 here , 14.6 idle af

    wot 12.8 a/f... most like 12.5 -13.0 for basic n/a.. not power adder:nono:

    10.9 is awfully rich/fat

    22.4 af is a :nono:
     
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  3. The O.G.

    The O.G. Member

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    i have recorded the following


    rpms a/f maf v
    idle 15.0 .74
    1500 14.6 .90
    2000 15.0 1.20
    2500 14.7 1.37
    3000 14.7 1.40
    3500 14.8 1.57
    all free reving in neutral

    wot
    rpms maf v
    2500 2.98
    3000 3.00
    3500 3.69
    4000 3.83
    4500 4.02
    5000 4.14
    5500 4.32
    6000 4.35

    af pretty much 12.75


    these were base tune numbers ,they have been cleaned up some since
    but ballpark numbers

    hope that helped:shrug:
     
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  4. Stanger007

    Stanger007 Founding Member

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    Hey Joe, what wideband and MAF are you using - different MAFs will read varying voltages at idle depending on how they are curved. Got a link to your mods?

    I do not think it is possible to idle a car in the 20s, it would be extremely, extremely rough if it did. I would question the wideband's reading if it appeared to be idling ok during that time.

    Idle/Cruise should cycle around 14.7, + or - about .75AFR.

    WOT N/A should be tuned to around 12.8-13.0.

    Are you running a T5 GT?

    Wes
     
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  5. JJ95GTID

    JJ95GTID Active Member

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    Engine:

    stock rotating assembly
    box stock Y303 heads
    Explorer intake with PP elbow
    stock throttlebody
    stock cam
    1.7:1 Cobra Rockerarms
    FRPP24lb injetors
    Summit 75mm MAF for 24lb inj

    I'm have a SummitRacing digital wideband (made by Innovate Technologies)
    Other gauges are: Cyberdyne fuel pressure, SummitRacing boost and narrowband.

    I know it sounds strange but it actually idles (roughly) with the wideband reading 22.4A/F. Another weird thing is that it doesn't get down to normal A/F until about 2k rpms.

    I installed the stock MAF and got the same results after tuning with the AirAdjuster. Again, the car won't idle without this device at all.
     
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  6. JJ95GTID

    JJ95GTID Active Member

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    Now this is what I would expect but for some reason my car isn't keeping the A/F at the stoic 14.7 ballpark range. :shrug:
     
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  7. JJ95GTID

    JJ95GTID Active Member

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    I would think this too but I have wideband and narrowband gauges. When the wideband reads 12.x-17.x the narrowband follows perfectly. The narrow band doesn't have a reading at idle. But, when crusing at 2k rpm the narrowband does its back and forth thing like it normally did before the 24lb injectors and Summit MAF.

    Yes, I have a T5 in my GT:nice:

    Also, my MAF (either one) voltage at idle is .76
     
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  8. Stanger007

    Stanger007 Founding Member

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    You don't have an exhaust leak around that wideband or a vacuum leak after the MAF do you?

    What's your fuel pressure at idle?

    Something strikes me as off if it was running lean on the 24s and stock MAF. You should have been about 10-20% rich. It should idle decent on the 24lb injectors w/ the "calibrated" MAF.

    That IST looks like it may be bandaiding a problem to me. :shrug:

    On a site note... Did you get a transfer sheet w/ that Summit MAF? I emailed Granatelli to get all their transfers but never heard back.

    Wes
     
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  9. JJ95GTID

    JJ95GTID Active Member

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    I think I got figured it out!!!!!

    Unmetered air! Just happened to be on the same side as the wideband sensor.

    I sprayed some carb cleaner on the passanger side and nothing happened. But, on the driver's side the engine picked up rpms. Using an air compressor I found the #7 lower intake runner leaking air at the intake to head gasket. This makes total sense!
     
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  10. Stanger007

    Stanger007 Founding Member

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    Hey Joe, ever get it resolved?
     
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  11. JJ95GTID

    JJ95GTID Active Member

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    Just got done replacing the intake gaskets and now it runs great :D

    3 of the cylinders were sucking air between the lower intake and heads :nonono:

    The FRPP MLS head gaskets don't have those tabs that hold the intake gaskets in place :notnice:
    So, they must've slid down when I put the engine together last time :notnice:
    This time I used a little dab of sealent to hold them in place :nice:

    Don't even need that IST Air Adjuster :mad: :rolleyes:
    I will still use it when I step up to larger injectors.

    Thanks for everyone's replies. It is greatly appreciated :nice:
    :SNSign:
     
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  12. Stanger007

    Stanger007 Founding Member

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    Cool, good to hear. :nice:

    Wes
     
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