idle issue after a tune up

  #1  
Old 03-03-2019, 11:30 AM
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Default idle issue after a tune up

After I did a tune up yesterday cap rotor plugs wires all factory parts and a new air filter and upon first fire the idle is going up and down before becoming normal again
 
  #2  
Old 03-03-2019, 12:23 PM
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well, your idle speed is managed by the idle air controller, which is a sort of shuttle-valve that lets controlled amounts of air bypass the throttle. if the IAC get sticky, you can get erratic idle speeds. on an 88, the engine speed is determined from the hall sensor that feeds the ignition system, the ignition system passes along a cleaned up version of the RPM signal to the ECU, and the ECU monitors the throttle position switch, when it sees the throttle is at idle, it watches the RPM and adds air via the idle air valve to keep it at a steady speed.
 
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