codes wont go away..they just change form **help**

Discussion in 'Fox 5.0 Mustang Tech' started by nitrous_bob, Apr 25, 2012.

  1. ok, after sitting all fall and winter broken its back running

    and running badly, it'll stall with the IAC unplugged, and idle is not in a good range. about 600-900 and bouncing

    i have to give it some throttle to start the KOER tests

    all vac lines look ok, replaced or inspected

    i'll start from the beginning just in case it helps

    KOEO dumped codes 91 and 96
    KOER dumped 12,21, and 91

    i COULD NOT run a cylinder balance just wouldnt stay running

    FP from my rail guage seems high with the stock reg, very bouncy with vac on, 38-45-ish
    and pretty much 45 with vac off

    so... i replaced the battery, ECT, i checked the o2 sensors and cleaned connections, i checked the IAC voltages, tps, and ...think thats it

    reset the computer..... drove about 20 miles mixed road and hiway

    new codes now

    cylinder balance test a 9 (still bouncy idle but no popping etc)

    KOEO = 11 only
    KOER = 12,94,44 (the smog system is removed)

    **EDIT** i should add that the Y pipe is removed, thermactor plugs inserted in heads, and the pipe from the pump to H pipe is closed and cut, all vac lines capped or removed

    will the 94,44 codes cause an issue ???? on 6 stangs this is the first one that i had drivability issues with

    and why cant i get it to idle correctly, what am i missing ???
  2. The 44/94 codes will not affect idle. They are only important if you have catalytic converters which will clog and fail without the extra air provided by the smog pump & controls.

    Your fuel pressure should stabilize at 37-41 PSI at idle, vacuum line to the fuel pressure regulator removed and capped. You may want to adjust the fuel pressure if you have an adjustable regulator. Stock regulators have no adjustment, which means you replace the regulator if the pressure falls outside of the 37-41 PSI limits.

    Code 12 -Idle Air Bypass motor not controlling idle properly (generally idle too low) - IAB dirty or not working. Clean the electrical contacts with non flammable brake parts cleaner at the same time.

    Recommended procedure for cleaning the IAC/IAB:
    Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damages some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. Reassemble and reinstall to check it out.

    Gunk Dip type carb & parts soaker:

    See the checklist below to set the base idle speed and help troubleshoot some of the other idle problems.

    See the "Surging Idle Checklist” for help with all your idle/stall problems. You can guess at the problem and throw parts at it, or you can use the checklist to help you find the problem quickly and inexpensively. It’s free and doesn’t cost anything: at last count there were more than 103,000 visits and still climbing

    The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the fixes & updates. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.