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Home >> Toyota >> 1990 >> Tercel DX, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 4-CYL CARBURETED >> Timing Control Systems >> Spark Control (SC) System Preliminary Inspection >> Tercel
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Spark Control (SC) System Preliminary Inspection: Tercel

  1. Disconnect vacuum hose at distributor sub-diaphragm (inboard hose). See Figure. Connect a vacuum gauge to sub-diaphragm. Ensure coolant temperature is below 77°F (25°C). Start engine and note vacuum reading while increasing and decreasing engine RPM.
  2. Vacuum reading should remain steady. Operate engine until coolant temperature exceeds 106°F (41°C). Operate engine and note vacuum reading while increasing and decreasing engine RPM.
  3. Reading should vary with manifold vacuum. Remove vacuum gauge and reinstall vacuum hose.
  4. On M/T models, disconnect main diaphragm (outer) vacuum hose and connect to vacuum gauge. With coolant temperature below 104°F (40°C), start engine.
  5. Note that vacuum gauge indicates no vacuum. Warm engine to 129°F (54°C). Accelerate engine to 2500 RPM and note that vacuum is indicated. Remove vacuum gauge and reinstall vacuum hose.
  6. On all models, remove distributor cap, rotor and dust cover. Apply vacuum to both diaphragms and note that distributor advance moves. Repair as necessary if no movement exists. If system operation is not as described, test individual components. Test BVSV "A", BVSV "B" (M/T), restrictor and check valve.
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