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Home >> Acura >> 1999 >> Integra GS-R, 2D Coupe >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0505: Idle Control System Malfunction
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DTC P0505: Idle Control System Malfunction

NOTE: Trouble shoot DTC P1508, if set, before proceeding.
  1. Start engine and hold at 3000 RPM, with transmission in Park or Neutral, until cooling fan comes on. Allow engine to idle. Using scan tool, ensure throttle position is about 10 percent with throttle fully closed and engine coolant temperature is 176-212°F (80-100°C). If throttle position and engine coolant temperature are within specification, go to next step. If throttle position or engine coolant temperature are not within specification, repair faulty sensor circuit.
  2. Using scan tool, check engine speed at idle with no loads (all accessories off). If idle speed is 700-800 RPM (non-VTEC) or 750-850 RPM (VTEC), problem is intermittent. System is okay at this time. If idle speed is 550 RPM (non-VTEC) or 600 RPM (VTEC) or less, go to next step. If idle speed is not 550 RPM (non-VTEC) or 600 RPM (VTEC) or less, go to step  4.
  3. Disconnect Idle Air Control (IAC) valve 2-pin connector. If engine speed does not drop or engine does not stall, replace IAC valve. If engine speed drops or engine stalls, adjust base idle speed. See ON-VEHICLE ADJUSTMENTS article. If engine speed does not adjust to specification, clean throttle body and ports.
  4. If vehicle is equipped with M/T, go to next step. If vehicle is equipped with A/T, turn ignition off. Remove intake air duct from throttle body. Start engine and let idle. Place finger over hole located next to throttle plate in throat of throttle body. If engine speed does not drop, go to next step. If engine speed drops, check engine coolant level and for air in cooling system. If cooling system is okay, replace fast idle thermovalve.
  5. Place finger on upper port in throttle body. If engine speed drops, adjust idle speed. If engine speed does not drop, check for vacuum leaks. Repair as necessary.
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