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Home >> GMC >> 1995 >> Forward Control 4.3 Z, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments - 4.3L. >> Ignition Timing >> 4.3L With Distributor
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4.3L With Distributor

  1. Set parking brake, block drive wheels and place transmission in Neutral or Park. Warm engine to normal operating temperature. Turn A/C off (if equipped). Ensure Malfunction Indicator Light (MIL) is off.
  2. Disconnect Tan/Black Electronic Spark Timing (EST) by-pass connector wire. DO NOT disconnect 4-wire connector at distributor.
  3. On models where engine computer is located underhood, on right fenderwell, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness near engine computer harness connectors.
  4. On models where engine computer is located in passenger compartment under right side of instrument panel, by-pass connector which is a single Tan/Black wire, breaks out of wiring harness where heater box and carpet meet on passenger side floor. Pull back carpet to expose single Tan/Black wire and connector on outside of control module harness.
  5. On all models, connect timing light to No. 1 spark plug wire. Check timing and adjust if necessary. See IGNITION TIMING . Reconnect EST by-pass connector. Clear Diagnostic Trouble Code (DTC).
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