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Home >> Mazda >> 1989 >> B2600i Base >> Repair and Diagnosis >> Engine Performance >> System >> System/Component Tests - CARBURETED >> Emission Systems & Sub-Systems >> EGR System >> System Inspection
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System Inspection

  1. Check vacuum hoses for correct routing, clogging or leakage. Repair or replace as necessary. Warm engine to normal operating temperature and allow to idle. Disconnect vacuum hose from EGR control valve and plug hose. If engine does not run smooth, check EGR control valve.
  2. Connect vacuum gauge to hose removed from EGR control valve. Verify gauge shows no vacuum with engine at idle speed. Accelerate engine and verify gauge shows vacuum. Decelerate engine. Verify gauge again shows no vacuum. If problem is found, check duty solenoid valve and "2L" and "2K" terminals of ECU. See PIN VOLTAGE CHARTS article.
  3. With vacuum hose connected to EGR control valve, "T" vacuum gauge into hose. Accelerate engine and note amount of vacuum. Disconnect vacuum hose from EGR valve and plug it. Accelerate engine. If gauge does not show higher vacuum reading, check EGR position sensor, duty solenoid valve and "1F" terminal of ECU. See PIN VOLTAGE CHARTS article.
  4. Disconnect vacuum hose from EGR control valve and plug hose. Disconnect electrical connector from coolant temperature switch. Jumper connector. See Figure . Accelerate engine. If gauge shows vacuum, check duty solenoid valve and "1Q" terminal of ECU. See PIN VOLTAGE CHARTS article. Reconnect temperature switch electrical connector and EGR vacuum hose.
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