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Home >> Buick >> 1980 >> Skyhawk Base, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Electronic Spark Control & Electronic Module Retard Ignition System >> Testing >> Electronic Spark Control >> Engine Detonation
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Engine Detonation

  1. Check engine coolant for proper level and concentration. Be sure detonation sensor connector is properly installed. Check initial timing against emissions label. Reconnect vacuum advance hose after timing check.
  2. If problems still exist, check ESC system by operating engine until warm. Turn air conditioner off and install tachometer. Set throttle fast idle cam on high step of cam. Engine RPM must be above 1800 RPM.
  3. Using a steel rod, tap front of intake manifold rapidly with medium-to-heavy taps. Observe engine speed drop of 200 or more RPM. Original RPM should be restored within 20 seconds after tapping stops.
  4. If RPM does not drop as noted, proceed to step  5). If RPM drops as noted, disconnect 4-wire connector to distributor. Insert jumper wire on distributor side of connector, between terminals "A" and "C". If engine does not run, check distributor as described under instructions for HEI is this section, If distributor checks OK, reconnect distributor to ESC controller. Check carburetor, turbocharger, or other systems.
  5. If RPM did not drop and return to normal in 20 seconds, check detonation sensor for physical damage, improper installation or wrong torque.
  6. Disconnect detonation sensor connector at cowl. On sensor side of harness, connect positive lead of an ohmmeter to connector terminal attached to center conductor of sensor. Connect negative ohmmeter lead to ground. Reading should be 175-375 ohms. If not, replace sensor.
  7. If reading is within specifications, remove sensor and substitute a known good sensor to connector. With engine running at 1800 RPM, hold sensor in hand and tap lightly on threaded end. Check for a 200 RPM or more drop. If correct, install new detonation sensor.
  8. If RPM did not drop in step  7) remove 10-pin connector at ESC controller. Install a jumper wire between terminals "A" and "B" of controller. Disconnect cowl sensor connector. Check continuity of sensor wire at cowl sensor connector.
  9. If there was no continuity, repair detonation sensor wire. If continuity exists, replace sensor and sensor harness between cowl and sensor. If trouble still exists, replace ESC controller.
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