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Home >> GMC >> 1998 >> Forward Control 6.5 F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing - 5.7L >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION >> Exhaust Gas Recirculation (EGR) System Check

Exhaust Gas Recirculation (EGR) System Check

  1. If powertrain OBD system check has been performed, go to next step. If powertrain OBD system check has not been performed, perform powertrain OBD system check. See POWERTRAIN OBD SYSTEM CHECK in TESTS W/CODES - 5.7L article.
  2. Remove heated oxygen sensor. Install exhaust backpressure tester in place of oxygen sensor. Start engine and let idle. If pressure reading is not 1.25 psi or greater, go to next step. If pressure reading is within specification, go to step 4).
  3. Increase engine speed to 2000 RPM on all engines. If pressure reading is greater than 3 psi (.2 kg/cm2 ) on all engines, go to next step. If pressure reading is not within specification, go to step 6).
  4. Check exhaust system for crushed pipe, internal muffler damage or heat distress. If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 6).
  5. Replace catalytic converter and go to next step.
  6. Operate vehicle within conditions under which original symptom was noted. If system operate properly, system is okay at this time. If system does not operate properly, go to step 2).
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