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Home >> Oldsmobile >> 1988 >> Cutlass Calais Base, 4D Sedan, 3.0 L >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Ignition System - Direct >> Testing >> Est Performance Check
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Est Performance Check

  1. The ECM will set timing at a specified value when diagnostic test terminal of the ALDL connector is grounded. To check the EST operation, perform the following steps:
  2. Start and run engine at 1500 RPM with the ALDL diagnostic test terminal NOT grounded. Ground test terminal. When ALDL test terminal is grounded there should be a noticeable change in engine RPM. When a fault in the EST system takes place, a code 42 should set.
  3. If a code 42 or 43 is set, use appropriate chart below for diagnosis. If the symptom is engine miss and the direct ignition system is suspected, use CHART C4M - DIS MISFIRE DIAGNOSIS below for proper diagnosis.
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