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Home >> Nissan-Datsun >> 1975 >> 280Z Automatic Trans >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Transmission Controlled Spark System >> Testing >> Vacuum Switching Valve >> All Other 1979 Models
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All Other 1979 Models

  1. With engine at normal operating temperature, disconnect vacuum switching valve wires at connectors and connect a timing light to engine.
  2. Start engine and adjust engine speed to 1600 RPM on 210 and 310 models, or 2000 RPM on all other models. Check ignition timing.
    NOTE: On 210 models with automatic transmission, place transmission selector lever in "N" or "P" for test.
  3. Connect one of the switching valve wires directly to the battery positive terminal and connect the other wire to ground. Recheck ignition timing.
  4. Vacuum switching valve is okay if ignition timing advances approximately 5° with wire connected to battery voltage. If not, replace vacuum switch valve.
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