Help me create the "Surging Idle Checklist"

Discussion in 'Fox 5.0 Mustang Tech' started by jrichker, Apr 10, 2005.

  1. hey 89 Gx maybe i'm not saying this right,what I mean is the compressor cycles on and off on the heat side,I don't mean it's is running the A/C,
    and you'll notice below 9 deg Celsius that your compressor won't cycle in and out and your compressor is basically a pulley then.
    That's what tweaked me to the rough idle,went away when it was below 9 deg.
    Hope you can understand all that.
    getting tired of typing,have a good one.
  2. My car idles around 800 but I have a rpm spike between shifts. any thoughts also what is IAC

  3. IAC= Idle air control. It is the thing that bolts to the front of your throttle body that has wires plug into it.
  4. my car had a pretty bad surge problem. used the checklist and l ceaned my IAC and my throtle body. idols real nice now. thanks
  5. How do you guys clean your throttle body? Doesnt it say not to clean it? Also were is the salt/pepper connector located?

    I bought that IAC adjuster from and it sucks!..used the new gasket that it came with and threw the rest! :nonono:
  6. Some TB's are coated and are marked "Do not clean". If they have no markings, spray them down & use a toothbrush to do the tough places that refuse to come clean. Spray some more and wipe up the mess with a paper towel. The rest will go through the engine with no problems.

    The salt & pepper shakers are the 10 pin connectors on the rear of the upper manifold.
    Photo courtsey of Tmoss & Stang&2birds.


    Attached Files:

  7. What kind of spray are you using to clean with
  8. Will you take a pic and draw on it where the pcv valve is? i dont know where it is. i have a 1990 5.0

    Attached Files:

  9. Still have this bad cold idle

    I have a cold start idle problem that lasts for about 5 mins of driving then is fine or if I shut it off and start it up again couple of times it seems to go away as well. It doesn't do the standard high idle at start anymore, rather it now surges up to 1500 RPM and the down to 100-400 RPM. If you don't give some throttle, it just dies.

    I have replaced the Idle Air Bypass
    Cleaned the ACT, Mass Air filiments
    tested the temp sensor at 180* it reads the right ohms (as per a Chilton manual)
    I should probably check it cold and clean Pin 10 as suggested in this thread.

    What else should I be looking at?
  10. The PCV is almost imposible to see unless you have the engine out of the car, have the intake manifold off, or you are a snail & have an eyeball on a stalk. :D

    The PCV fits in a rubber grommet that plugs in the block at the rear of the lower intake manifold. The rubber grommet is notorious for not fitting tight or sealing like it should. It connects to the upper manifold by a 3/8" vacuum hose coming from the rear of the upper intake manifold. The easiest way to find it is to follow the hose with your hand and pull it out of the rubber grommet. Check the screen below the PCV while you have it & the grommet out if you can get to it.
  11. It's in a tough place to get at, right straight behind the upper intake in the the lower intake. A 3/4 in (approx.) hose goes to it from the upper. Got to reach down in there to get at it.
  12. also, i find it easiest (on a fox) to stand on the driver side to remove it. to get the screen below the grommet and valve out, a magnet works for some; i use a pair of really long needle nose pliers. a curved dental pick would work too. if you buy a new screen ahead of time, you can see what it looks like and how to grab ahold of it.

    good luck.
  13. thanks for the help, i found it. :)

  14. Just a little more on that, my basket was really stuck in there ( I mean really stuck!!!!) I ended up using a tool that I made to get it out. I use a bolt that I welded a screw on the end of it, the screw really digs in on the basket and the bolt head give you something to grab on to. If it helps any one :rolleyes:
  15. good point - i have known of people having luck with the screw method as well. :nice:
  16. Checked the Temp Sender cold and its is open, should show 58k, so says the manual. So I will change and post the results.
  17. Ranchero,

    Can you elaborate on this? I've been fighting a fairly rich/rough idle for a few months now. All sensors are new and less than 30,000 miles old. Even shade tree data logged the ACT and ECT. They looked fine. Engine pulls 19.5 in vac at idle. The problem can be partially solved by resetting the computer. After a few thousand miles of driving, part throttle response and gas milage decrease, and the car once again settles into a rich idle. Where is this fusible link located and how can I fix it?

  18. Although u mention vacuum lines i would specifically mention pcv valve and the pre-formed hose that goes with it because this seems to be an extremely common problem. As others have stated.
  19. Don't know if these 2 would help but...
    1. Replace fuel filter
    2. Dont forget the Seafoam
  20. ........

    I bought a car that wouldn't start until about the third time. Then it would not have the fast idle after it finally started. It turned out to be the computer. It had a Cobra computer. The Cobra computer is set up a little different.