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Home >> Ford >> 1991 >> Explorer 2D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Adjustments >> Idle Speed & Mixture >> 4.9L, 5.0L (W/ E4OD), 5.8L (Under 8500 GVW), E250 W/ 0-64K Calibration & All 1991 1/2 5.8L

4.9L, 5.0L (W/ E4OD), 5.8L (Under 8500 GVW), E250 W/ 0-64K Calibration & All 1991 1/2 5.8L

  1. Connect Scan tool to diagnostic connector. Enter KOER self-test. A single-pulse tone indicates entry mode has been successfully entered. Observe "Scan" tool read-out.
  2. If a constant tone, solid light or STO LO is displayed, base idle speed is within range and adjustment is not necessary. Exit self-test.
  3. If a beeping tone, flashing light or STO LO at 8 Hz is displayed, TPS is out of range and adjustment may be required. Perform adjustment and repeat test.
  4. If a beeping tone, flashing light or STO LO at 4 Hz is displayed, base idle speed is too high. Go to step 8).
  5. If a beeping tone, flashing light or STO LO at one Hz is displayed, base idle speed is too low. Go to next step.
  6. DO NOT clean throttle bore. Check throttle plate for presence of throttle plate orifice plug. See Figure. If there is no plug, turn idle adjusting screw CLOCKWISE only to adjust idle speed until conditions in step 2) are obtained. If there is a plug from previous service, remove it and turn screw to obtain conditions in step 2). After adjustment, screw MUST be in contact with lever pad.
  7. Perform a KOEO Self-Test to ensure TPS fault code is not present. Move throttle plate to ensure it is not stuck in bore and linkage is not keeping throttle from closing. On models with automatic overdrive transmissions, check throttle valve adjustment.
  8. If idle speed is too high, turn engine off. Using tape, block off orifice in throttle plate. See Figure.
  9. If orifice is already plugged, go to next step. On mass airflow engines, reconnect air cleaner hose. On all models, restart engine and check idle speed. If engine stalls, crack throttle plate open using throttle plate stop screw. If idle speed is still too high, go to next step. If idle speed drops to specification or drops lower than specification, go to step 11).
  10. Perform KOEO self-test. If fault codes are present, repair as necessary. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section. If TPS fault code is present, check for proper TPS output. See THROTTLE POSITION SENSOR (TPS) . Ensure adjustment screw is in contact with lever pad. If fault codes are not present, see H - TEST W/O CODES article in the ENGINE PERFORMANCE Section.
  11. Turn ignition off. Remove air cleaner hose and remove tape covering throttle plate orifice. Select correct color plug for orifice. Plugs are available in Throttle Plate Plug Kit (FOPE-9F652-AA).
  12. Reconnect air cleaner hose and start engine. Recheck idle speed. If idle speed is not within specification, turn adjusting screw CLOCKWISE to obtain correct idle speed. After adjustment, screw MUST be in contact with lever pad.
  13. On all models, perform a KOEO self-test to ensure TPS fault code is not present. Move throttle plate to ensure it is not stuck in bore and linkage is not keeping throttle from closing. On models with automatic overdrive transmissions, check throttle valve pressure adjustment.
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