Idle Comes Down With Clutch Pedal Depressed???

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by erniet17, Dec 30, 2013.

  1. erniet17

    erniet17 Member

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    Is it normal for the idle to come down about 150 RPMs when depressing the clutch and the tranny in neutral?

    Thanks in advance!
     
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  2. mikestang63

    mikestang63 Mustang Master

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    Nope . Run the codes. Most likley your IAC, TPS or MAF
     
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  3. Dave2000GT

    Dave2000GT Active Member

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    That is perfectly normal when your neutral gear switch is broken.
    Try to run the codes, and I bet you can't get the engine running codes unless you hold in the clutch the entire time. You can replace it.. or just do what I did and short the wires going to it, tricks it into thinking it's always in neutral and fixes the idle issue. Haven't had any adverse effects yet...
     
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  4. erniet17

    erniet17 Member

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    I did replace the clutch switch with a parts store one a few months ago. I have a brand new Motorcraft TPS that I still need to install but the weather has been terrible.

    I believe you have to keep the clutch down during the KOER test??? Although I have bypassed it in the past but I'm trying to get everything to work a it should.
     
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  5. Mustang5L5

    Mustang5L5 Car used in adult film "Highway Gangbang-InDaButt"
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    Run the codes. That should give you a hint as to the issue. Right now, we are just guessing.

    It is possible to run the codes without holding the clutch down. However, you should hold it down to eliminate the code 67.
     
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  6. erniet17

    erniet17 Member

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    Ok, didn't mean to disappear but my car was without a fuel pump for a month. It's now back up and running. I replaced the TPS with a new OEM one and the idle still drops when I press the clutch.
     
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  7. erniet17

    erniet17 Member

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    Still having this problem. I have gone through the whole Surging Idle Checklist and still have had no luck. Any ideas??
     
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  8. hoopty5.0

    hoopty5.0 Mustang Master

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    So... you get a code 11 when you dump codes?
     
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  9. jrichker

    jrichker StangNet's favorite TOOL
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    Did you just read though it or actually do it step by step?
     
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  10. erniet17

    erniet17 Member

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    I only get the codes regarding the smog stuff that has been removed for years.
     
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  11. erniet17

    erniet17 Member

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    I printed it out and took it outside with me and went down the list.
     
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  12. jrichker

    jrichker StangNet's favorite TOOL
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    Did you do the TPS setting and testing? Check the TPS base setting and then advance the throttle and watch TPS voltage steadily increase?
    Have you checked and cleaned the 10 pin connector pins?

    Have you cleaned the IAC using a Gunk or Berryman soak type cleaner and then set the base idle according to the instructions in the second post?
     
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  13. erniet17

    erniet17 Member

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    The old TPS was good and I replaced it with a new Motorcraft anyways. I tested that one as well and it is good. I have cleaned the 10 pin connectors and put dielectric grease on them. I let the IAC soak and I even used my friends IAC from his car. No improvements.

    One thing I noticed recently was that I had a lot of sucking through my oil fill neck. If I would turn off my engine, and then take off the oil fill cap, it sounded like I was opening a can of beer. I have a TFS fill neck and I didn't have the nipple hooked up to the throttle body. I installed the nipple and hose and the sucking is gone.

    Can that be an indication of a bad lower intake gasket? I have sprayed about 4 cans of brake cleaner and not noticed any changes.
     
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  14. jrichker

    jrichker StangNet's favorite TOOL
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    Put a vacuum gauge on the engine. You should see 16"-18" of vacuum at idle.
     
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  15. erniet17

    erniet17 Member

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    I did that a while back but I honestly do not remember what the numbers were. It was somewhere around 14-16 and the needle was pretty steady. The short block has a ton of miles on it and was turbo'd at one point. It still runs great but not sure if that would affect the vacuum.

    I don't have a gauge but I can get one within a couple of days and I'll post up the numbers.
     
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  16. erniet17

    erniet17 Member

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    I'm just gonna pull the intake off and check those gaskets. I used the 1250s that most people have problems with although I have not had any issues in the past that I'm aware of.
     
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  17. jrichker

    jrichker StangNet's favorite TOOL
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    Test, Diagnose and Think - TDT -it saves time labor and money in the long run.

    It also eliminates the problems created when something you needlessly swapped causes more problems.
     
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  18. erniet17

    erniet17 Member

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    I agree, I just don't know what else to check or change out. I've been having this problem for months now and I have checked every connection and setting. It idles at about 1100-1200 and then comes down to about 950 with the clutch in. It drops a bit more with the a/c on. My gas mileage is horrible too. That's why I'm leaning towards a vacuum leak and I've checked every vacuum line and sprayed several cans of brake cleaner.
     
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  19. 7991LXnSHO

    7991LXnSHO Well-Known Member

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    @Dave2000GT I hope I misunderstand what you did. Bypassing the neutral safety starter interrupt switch will cause a nasty surprise sometime when your wife or kid starts it in gear. I hope you have styrofoam filled boxes in front of where you park.:bang:
     
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  20. erniet17

    erniet17 Member

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    I bypassed it temporarily while troubleshooting. Although my wife and kid don't come near the car, I reconnected it cause I like to have things function as they should. At least most things.
     
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