Change In Idle After 3g Swap..

Discussion in 'Fox 5.0 Mustang Tech' started by billison, Aug 18, 2013.

  1. Ok.. Ill start by saying it may be just in my head but it seems like my (92. 5.0 5 speed) idles slightly higher now.

    For the swap. I...
    Used 94 v6 alt,

    Used the premade harness from eBay .

    Ran a 4g fused power wire from the alt to the solenoid.

    Ran a 4g ground wire from the ground by the battery that the computer uses and ran it to front of block.

    The only thing I didn't do was run a new one at the rear to the firewall ( original is in place)

    Like I said.. It may be in my head but it felt different...

  2. 1.) Make sure you didn't knock any vacuum connections loose as a first step.
    2.) Dump the codes and fix them.
    3.) 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 damage 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:

    Setting the base idle speed:
    First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. If you have a wild cam, you may have to raise this figure 100-150 RPM or so. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s. This figure will increase if you have a wild cam, and may end up between 800-950 RPM

    Remember that changing the mechanical idle speed adjustment changes the TPS setting too.

    This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.

    Disconnect the battery negative terminal and turn the headlights on. Leave the battery negative terminal disconnected for 5 minutes or so. Then turn the headlights off and reconnect the battery. This erases the computer settings that may affect idle performance.

    Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. A wild cam may make it necessary to increase the 600 RPM figure to 700 RPM or possibly a little more to get a stable idle speed.
    Changing the mechanical adjustment changes the TPS, so you will need to set it.

    When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads. A wild cam may make this figure somewhat higher.
  3. Just did mine too, it changed some also. The pulleys are a little different size which adds to the mix as well. Basic idle reset fixed mine no prob.
  4. You should swap back the pulley from your old 2G to the new 3G, as it is smaller and will help charging at idle and avoid this problem.

  5. Ok, removed both pullies . The 2g pullie touches the 3G housing. I assume I simply need a very flat washer?
  6. believe i've read where people did that with no issues.
  7. Did what? Used a washer?
  8. yes use a flat washer, sorry for no quotes
  9. Just a quick update. I stopped by my local sears hardware. They had the part I think I needed. I took the 2g spacer and found the same thing only thinner. It's called a "spacer bushing". Ill test fitment tonight.
  10. Worked like a charm.
    Grabbin' Asphalt likes this.
  11. another project done
  12. Yup! Removed the trailer hitch the last guy installed too!
  13. you my friend, are a machine
  14. My 2 year old helped!!
  15. I used a washer for my pulley. Simple 3 cent washer with 5/8" diameter hole is all you need.