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Home >> Mercedes Benz >> 1990 >> 560SEC >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Ignition System (EZL Ignition) >> Engine Running
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Engine Running

  1. Run engine at idle (operating temperature). Check ignition timing for 7-11 degrees. If timing is not 7-11 degrees, go to next step. If timing is 7-11 degrees, go to step 4).
  2. Pull plug from throttle valve switch connector. Test resistance of throttle valve switch on connector. Reading between terminal Nos. 1 and 2, (idle speed position) about zero ohms; between terminal Nos. 2 and 3, (full load position) about zero ohms; between terminal Nos. 1 and 2 and Nos. 2 and 3, (partial load) infinity. If readings are not as specified, adjust or replace throttle valve switch. If okay, replace ignition control module.
  3. Run engine at 3200 RPM. Check ignition timing (vacuum line connected) for 40-44 degrees ATDC at 3200 RPM. If timing is not as specified, go to next step. If okay, go to step 6).
  4. Check vacuum line from intake manifold to ignition control module for leaks. If no leaks are present, check resistance of reference resistor (EZL). Pull sensor signal input plug on ignition control module (Brown/Yellow Green/ Black wire). Check resistance with ohmmeter between connector terminal No. 3 and ground.
  5. Resistance should be 750 ohms. If okay, replace ignition control module. If resistance is not as specified, check wire for open or replace connector. Go to next step.
  6. Pull vacuum line from ignition control module and run engine at 3200 RPM. Check ignition timing for 27-31 degrees at 3200 RPM. If okay, go to step 8). If timing is incorrect, go to next step.
  7. Unplug coolant temperature sensor. Test resistance from sensor terminal to ground. Test resistance at 2 different temperatures. See Figure . If not within specifications, replace sensor. If values are okay, go to next step.
  8. Run engine at 3200 RPM (vacuum line connected). Check dwell angle for 24-53 degrees. If dwell angle is not correct, replace ignition control module. If okay, test is complete.
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