94 Gt Wont Idle Down

Discussion in '1994 - 1995 Specific Tech' started by stanger9410, Apr 30, 2013.


  1. stanger9410

    stanger9410 Member

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    Before i start i want to say that i have looked at the surging idle checklist, and performed most of the items I believe to apply.

    So I have a 94 GT, cobra upper and lower, 24lb injectors, 24lb cobra MAF, adjustable regulator, 255lph fuel pump, BBK equal length shorties, bassani x-pipe and mufflers, MAC Cold air, a SCT chip with a Brenspeed tune, Smog pump delete with pulley.

    After we installed everything but the x-pipe and mufflers and cold air i lost the computer, when i replaced the computer it ran good for a few months then it started to not want to idle down to correct idle speed at about 8-900 RPM. Also when i push in the clutch between 2-3000 RPM it revs up about 500RPM and then slowly idles down. It doesnt do any of this until the temp needle moves, the second it moves the slightest it will start having a poor idle. When i replaced the computer i was sure to match it with the correct T4MO for my car so i know i have the correct one. I have replaced the IAC, TPS, and cleaned my MAF, I have also tried putting a MAF that i know to be in good working order on my car and still no change. I have also checked multiple times for vacuum leaks using carb cleaner while the motor is running. Yesterday i pulled codes and got 511, 10, and 157, with the KOEO, with the KOER i got a CYL 8 and a 111. I know that 511 means Read Only memory test failure, but im not sure exactly what that means. I could not find 10 on my sheet, and 157 was Manifold Air Flow sensor low voltage. Im assuming that is the mass air? which puzzles me because i already checked it. I dont know what the CYL 8 Means either, and the 111 means system pass. So im stumped here, i would appreciate anyones advice, and im willing to try anything at this point.
     
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  2. ratio411

    ratio411 Founding Member

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    I would point out that you need to check that the MAF itself is calibrated for 24# injectors.

    I know in 93 that the Cobra was calibrated in the ECM for 24#ers, NOT the MAF.
    So, if you use 24# injectors and Cobra MAF with a non-Cobra ECM, you are then NOT calibrated for 24s.
    I am not sure, but I believe the same is true for the 94/95 Cobras... and if that is the case, you are running 24s on a 19# calibration.
    If the car is getting too much fuel, and your o2 sensors are good, the ECM will add air (RPMs) to burn off the extra fuel, instead of letting the engine load up (run rich).

    There are 2 ways to calibrate for 24s...
    1: Aftermarket MAF calibrated for 24s and non-Cobra ECM.
    2: Cobra ECM (or custom tuned ECM) with stock MAF.

    Ford used the 2nd method, preferring to calibrate the ECMs, not the MAFs.


    Edit:
    I might have misread your original post.
    Did you continue to use your custom tuned chip?
    If so, then nevermind... you should be good to go if they calibrated you properly.
     
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  3. Chythar

    Chythar Well-Known Member

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    94-95 Cobra MAF's are the same as the GT MAF. The Cobra computer compensates for the calibration difference. The 511 code is standard when you have an aftermarket chip plugged into the computer; only worry about the 511 code when you do NOT have a chip plugged in.

    Our computers only give out 3-digit codes, so either you miscounted blinks or your code reader isn't set up for our computers. I suggest re-reading the codes before you try to look into the code 157 - you may have read the code wrong.

    HOWEVER, according to our own Venom351R on another forum, code 10 is a separator code. Don't remember seeing it, but I think he's trustworthy. :D Your code 157 may be accurate then.

    http://sn95forums.com/showthread.php?32408-OBDI-EEC-IV-Diagnostic-Codes
     
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  4. stanger9410

    stanger9410 Member

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    I believe my MAF is good because I have swapped mine with my brothers that I know is calibrated for 24lb injectors. I bought a code reader so I know I got the 157 code. I am still running my chip, I'm going to be calling my tuner this week and checking into what all that tune sets. Thanks for your input guys, I'm seriously stuck here. I'm having the motor smoked this weekend so I can either find a vacuum leak or rule it out completely
     
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