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Extremely Low Idle

Discussion in '80-Series Tech' started by Bradass80, Nov 10, 2003.

  1. Bradass80

    Bradass80

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    While wheeling this past weekend i hit a good size hole which caused the postive battery cable to pop off, after i put it back on my truck now idles at about 300rpm instead of the 600rpm it was at, what would cause this to happen? I have no ideas!! Oh yeah 1992, 3FE w/ turbo, 192,000 miles, TIA, Brad.
     
  2. ppc

    ppc M Go Blue

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    The ECU gets reset and must relearn parameters. After a few normal start/run cycles it should recover. If it doesn't look for loose or broken vacuum lines or the air intake rubber tube may have cracked or broken allowing unmetered air into the engine.
     
  3. IdahoDoug

    IdahoDoug

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    If it does not relearn the idle speed and the big tube from the air cleaner isn't cracked on the bottom of the bellows section (from pushing up on this old tube to change air filters), then consider cleaning your throttle body. I did this simple operation (15 minutes) and the occasional low idle that was happening randomly went away. I found it was because the throttle position sensor expects a certain amount of air to come through based on the throttle plate's position. However, their was accumulated gummy tarlike junk in the valve seat that was not allowing the expected amount through to the engine. The fix was immediate and permanent - has not happened again in 3 years.

    Doug