Grrr....more car problems

Discussion in 'After Hours Lounge (Off Topic)' started by Tim Hoover, Jan 19, 2005.

  1. Tim Hoover

    Tim Hoover Screenwriter

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    Okay, time for the mechanics to speak up again [​IMG]

    My '87 Mustang GT is having idle problems. Basically, it won't idle at all. The engine revs up and down, and then it stalls out. I have to keep constant pressure on the gas pedal to prevent this. I've followed the Chiltons manual for resetting the idle speed, but to no avail. Any thoughts?

    One more thing...the blower speed switch won't work on anything but the highest setting. I thought it was the switch itself, but after replacement it's still doing the same thing. Any thoughts on this as well?
     
  2. Tim Hoover

    Tim Hoover Screenwriter

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    You know, it just occurred to me that I asked this exact same question a few months back...I'll search for my own thread and investigate.
     
  3. Kevin G.

    Kevin G. Second Unit

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    My brother had an 86 F150 that had pretty much the same motor as your GT. His idled like SH#T for a while, Up and down, up and down...scanned it and showed o2 sensor... Changed it and had no more worries.
    Prob. a relay for the blower switch...just guessing here though.
     
  4. Bob Graz

    Bob Graz Supporting Actor

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    Classic leaky vacuum hose symptom. Check the vacuum lines.
     
  5. Karl_Luph

    Karl_Luph Supporting Actor

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    I agree with Bob here, especially on this age of vehicle.It could be one of the vaccum lines that hook up to the a/c heater controller on the dash or a vacuum line under the hood. The rubber vacuum lines get hard and brittle with age,heat,oxidation,fuel,oil etc. and they deteriorate getting cracks and sometimes just turning to mush depending on what they are exposed to. Have someone start the car and keep it running while you look under the hood and listen for a high pitched hiss,sometimes this is easiest to centralize using a section of heater hose pressed to the ear.(Don't laugh, it works!lol) Some mechanics just use gumout and spray around the engine compartment.If there's a leak the engine's rpm's will change when the gumout is sucked in by the vacuum.
     
  6. Eric Kahn

    Eric Kahn Guest

    If it is the multi port 5 liter, you also need to clean the throttle body, easy to do, just disconnect the air feed from the filter and hold it open with your hand and reach in and clean it with a rag that you have sprayed carb cleaner on
    while you are doing that, you can check and see if the throttle plate pivots freely, if not, that could cause your problem since the idle speed motor is constantly adjusting the throttle plate
     
  7. Tim Hoover

    Tim Hoover Screenwriter

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    The vacuum lines under the hood are fine, as they have been replaced very recently. My earlier thread, which I finally found, suggested cleaning the IAC valve...which I will do as soon as I can get the damn thing to actually come off. I'll go ahead and clean the throttle body while I'm at it, since I have to disconnect the big intake hose to reach the screws holding the IAC in place.
     
  8. Tim Hoover

    Tim Hoover Screenwriter

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    Time for an update...I gave the IAC and throttle body a good cleaning, and the idle problem is solved. It's purring like a kitten now.

    However, the problem w/ the blower speed switch remains, and I have absolutely zero clue where to even start. Like I said earlier, I replaced the switch itself w/ no success...
     
  9. Steve Schaffer

    Steve Schaffer Producer

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    Tim,

    If the blower only works on Hi and you've eliminated the switch as a possibility the most likely problem is a little doohickey called a blower motor resistor. Don't know where it is on your car but on most makes it's the most common cause of your problem.

    Typically the resistor has 2 or 3 different resistor coils in it, and the switch selects between them to vary the amount of current going to the motor to vary the speed. Since Hi wants the full available current it does not go thru the resistor, which is why that still works.

    The blower motor resistor on most cars is usually mounted on the blower motor housing, has a connector going to it with something like 4 wires. This housing may be under the hood or behind the glovebox area, depending on make. It's mounted in such a way that air is blown past it for cooling as the resistor coils get hot.
     
  10. Tim Hoover

    Tim Hoover Screenwriter

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    Steve - thx for the info. Looks like I have a small job this weekend [​IMG]
     
  11. Tim Hoover

    Tim Hoover Screenwriter

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    Lovely....Motorcraft part # YH445 blower resistor pack has been declared obsolete by Ford and is no longer available. Is there a way to rebuild these things?
     
  12. Karl_Luph

    Karl_Luph Supporting Actor

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    Have no fear Tim, nowadays junk yards can find used ones in a jiffy. Get two while you're at it[​IMG]
     
  13. Tim Hoover

    Tim Hoover Screenwriter

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    Karl - lol...looks like that's what I'm gonna have to do. I'm stocking up on these bastards as I foresee a good market for them [​IMG]
     
  14. Steve Schaffer

    Steve Schaffer Producer

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    Some makes use separate fuses for hi vs the other speeds, don't know about Ford.
     

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