94 cobra run rough, cuts off, but runs a little better with MAF unplugged

Discussion in '1994 - 1995 Specific Tech' started by webshot, Mar 23, 2013.


  1. webshot

    webshot Member

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    My 94 cobra is experiencing some weird issues. The car runs rough as it stands and when it warms up it will try to cut off and if it does wont start until car cools off a little. But what is stranger when the MAF sensor is unplugged it will run better, but the end result is the symptom before (shutting off not starting). I notice a good deal of white smoke when I drive it was well. The only mods are, cold air intake, GT40x heads and TFS Stage 1 cam. Any ideas or things I should look at? Any advice, help, tips, links appreciated.

    Update, car does not run when MAF is plugged. I figured out that the MAF sensor is for a stock air box set up, meanwhile I have a PRO-M (pn 14557/14556) Mass air Meter. I also discover that the Throttle body seems to be some off brand and has "65mm" on it. Could these components be the root source of my issues? Here are some pics of the setup.

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    [​IMG]
  2. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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  3. webshot

    webshot Member

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    ooops sorry no codes. As in everything checked out. Actually when the battery is charged I will run again.
  4. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    i would run jrichters "surging idle checklist"
  5. webshot

    webshot Member

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    ok update, with the key on engine not running I get the following codes.

    111
    10
    157

    Now the car will not run at all with the MAF plugged in! So I am not able to get a reading. I start the car with MAF unplugged, plug my scanner in then plug in MAF car instantly dies.
  6. earleys94gt

    earleys94gt Active Member

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    Have you tried to clean the MAF?
  7. webshot

    webshot Member

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    Earleys, yes I have.
  8. webshot

    webshot Member

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    I think I may know why this is messing up. Seems the Mass Air Flow sensor is a stock replacement. But I have a pro-m mass air meter. Could that be causing the issue? Also I have the stock tubing hooked up to it, so it is incomplete. Any ideas if this could be the root of the problem?
  9. webshot

    webshot Member

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    added some pics and additional information to the first post.
  10. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    did it just start doing this?
  11. webshot

    webshot Member

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    Yes.... well kinda. The car has always ran really rough, thus it went into a shop. The shop replaced the MAF sensor with a stock replacement from autozone. I have since taken the car back to my house due to the guy not having time to work on it. I didnt notice the "Pro-M" casting on the Mass Air Meter until just now. The unplugged maf issue is new (since replacing the MAF).

    One thing the shop noticed was a dead injector. They replaced that, and the car does seem to have more power, but still running rough, and shutting off when warm.
  12. toyman

    toyman Active Member

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    I think the Pro-M MAF housing was intended to allow the install of the filter without using the stock air box. However, it may have originally had a MAF sensor specific to that application. IIRC the stock TB had 65 MM casting on it. How long have you had the car and did you ever give it a baseline tune, such as plugs, wires, rotor and cap. Code 111 is a pass code there is no code 10 (all codes are 3 digits) and 157 is a bad MAF.
  13. webshot

    webshot Member

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    I have had the car for a few years. It has been sitting and never really ran right. But I am trying to get it together for the summer. Yes I did change plugs, wires and the cap and rotor. I think the MAF I got is still under warranty from Autozone. Sounds like I should try to swap them out?
  14. revhead347

    revhead347 I have face herpes.

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    It could also be related to the cold air installation. Clear the codes and start it up with a piece of cardboard between the filter and the engine. I've seen open filters like that get messed up from the air coming off the fan. More likely it's a bad MAF though.

    Kurt
  15. webshot

    webshot Member

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    Thanks Kurt, I will try that. So you mean literally place cardboard like around the filter to prevent air from coming off of the electric to the filter? Just making sure I understood ya.
  16. revhead347

    revhead347 I have face herpes.

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    Yeah, that's exactly what I'm talking about. Some of those cold air setups direct air into the MAF at the wrong angle and it messes up the reading. The fan blowing on the filter aggravates the situation. You can also try reclocking the MAF so that the sample tube is at a different location relative to the filter. I would say tap into the MAF to see what reading you are getting, but if it won't run with the MAF plugged in, you really can't do that.

    Kurt
  17. WhiteCobra95

    WhiteCobra95 Member

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    What injectors are you running? (19 lb/hr orange top or 24 lb/hr blue top)

    If I'm understanding your post correctly, the shop pulled the MAF element out of the Pro-M housing and replaced it with a stock MAF sensor element. I'm guessing that the Pro-M MAF the shop pulled out was tweaked for 24 lb/hr injectors, which is why the car ran before but rough. ...just my guess.

    You might also check to see if your ECU was chipped. Someone might have done it correctly and changed the calibration for the Pro-M MAF and injectors (assuming you have higher flow injectors), and now the stock MAF is just incompatible with the cal.

    Also, that 65mm TB looks like a ford racing throttle body. They're the only ones I can remember that cast the size into the body like that.

    Good luck!
  18. webshot

    webshot Member

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    WhiteCobra I will check into the injectors when I get home. I was told it had 24lb injectors, but never verified myself by checking the color. Also how does one check the ECU? I think you are correct on the TB as well, I been researching and found that to be true as well. That being the case is it compatible with my setup? One last question (well 2) to check the injector top color will I need to pull the manifold?

    Side question, what do I need to check or how do I check the fuel pressure? I found a thread here that mentioned something about fuel pressure.

    I really appreciate the help guys.
  19. toyman

    toyman Active Member

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    Injector top color is visible without anything being removed. To test the fuel pressure you need a gauge that will thread onto the schrader valve on the fuel rail, passenger side towards the front.
  20. webshot

    webshot Member

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    Update:

    Got a new MAF, cleared the codes. Car still does not run with MAF plugged in. Car now cranks over, I can keep it running by vigorously pumping the gas pedal. But when I do that I hear backfires coming from under the hood. When I check the codes now I get.

    564, 564
    111, 111.

    Could it be bad timing? I am starting to feel like this car is possessed...smh :(

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