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Home >> Suzuki >> 2001 >> Swift GA, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected, Or P0301-P0304 Cylinders No. 1-4 Misfire Detected >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. Perform DTC CONFIRMATION TEST . If DTC P0300, P0301, P0302, P0303 or P0304 is set, go to next step. If DTC P0300, P0301, P0302, P0303 or P0304 is not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
  2. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs other than DTC P0171, P0172, P0300, P0301, P0302, P0303 or P0304 is set, repair those DTCs first. If no other DTC is set, go to next step.
  3. Remove spark plugs and check for proper gap. Check for carbon deposits or cracked insulators. Ensure correct spark plugs are installed. Repair or replace as necessary and go to DTC CONFIRMATION TEST . Disconnect all injector connectors. Using a spark tester, ensure a strong, Blue spark is present at each plug wire. If a strong, Blue spark is present at each plug wire, reconnect injector harness connectors and go to next step. If no spark or a weak spark is present, check ignition system components. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article.
  4. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. With key on and engine off, fuel pressure should be 38.4-44 psi (2.7-3.1 kg/cm2 ). With engine running at idle, fuel pressure should be 28.4-34.1 psi (2-2.4 kg/cm2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST B-3: FUEL PRESSURE INSPECTION under SYSTEM TESTS in BASIC DIAGNOSTIC PROCEDURES article.
  5. Inspect fuel injectors and fuel system circuit. Go to CIRCUIT TEST B-1: FUEL INJECTOR CIRCUIT INSPECTION under SYSTEM TESTS in BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary and DTC CONFIRMATION TEST . If fuel system is okay, go to next step.
  6. Disconnect PCV valve from valve cover. Start engine and allow it to idle. Check for vacuum at PCV valve. If vacuum is not present, disconnect PCV valve from hose. If engine runs rough or stalls, replace PCV valve. If engine does not run rough or stall, check for restriction in PCV hose. Repair as necessary and go to DTC CONFIRMATION TEST . If PCV system is okay, go to next step.
  7. Turn ignition off. Allow engine to cool. Disconnect purge hose from EVAP canister purge line located next to EVAP canister purge valve. See Figure. Start engine and allow it to idle. Place finger over end of disconnected hose. If no vacuum exists, go to next step. If vacuum exists, check EVAP canister purge valve. See FUEL EVAPORATION in SYSTEM & COMPONENT TESTING article. Repair as necessary and go to DTC CONFIRMATION TEST .
  8. Check MAP sensor operation. Go to DTC P0106: MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT PERFORMANCE PROBLEM . Repair as necessary and go to DTC CONFIRMATION TEST . If MAP sensor operation is okay, go to next step.
  9. Check ECT sensor operation. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. Repair as necessary and go to DTC CONFIRMATION TEST . If ECT sensor operation is okay, go to next step.
  10. Check engine compression. Engine compression should be a minimum of 156 psi (11 kg/cm2 ) at 250 RPM with a maximum variation of 14 psi. If engine compression is okay, check valve lash and valve timing. Repair as necessary and go to DTC CONFIRMATION TEST . If no problems are found, go to next step.
  11. Check PCM harness connections and grounds for corrosion or loose terminals. Repair as necessary and go to DTC CONFIRMATION TEST . If connections are okay, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article. Repair as necessary and go to DTC CONFIRMATION TEST .
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