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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 254 (Engine Controls - Trouble Shooting - No Codes - 2.2L) >> Symptoms >> Rough, Unstable Or Incorrect Idle & Stalling >> Sensor/System

Rough, Unstable Or Incorrect Idle & Stalling: Sensor/System

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check for the following that may cause the engine to run rich:
    • Any water intrusion in the HO2S connector.
    • The engine oil contaminated by fuel.
    • An EVAP canister purge condition.
    • Incorrect fuel pressure. Go to FUEL SYSTEM DIAGNOSIS (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
    • A leaking fuel pressure regulator. Go to FUEL SYSTEM DIAGNOSIS (GASOLINE) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
    • Any vacuum hoses that are split, kinked, or improperly connected.
    • An air intake duct that is collapsed or restricted.
    • An air filter that is dirty or restricted.
  2. Check for the following conditions that may cause the engine to run lean:
  3. Check for the following conditions which cause an incorrect idle speed:
    • Any throttle body tampering, excessive deposits, or damage.
    • A restricted air intake system.
    • A large vacuum leak.
  4. Check the Throttle Position (TP) sensor and related wiring. Go to DTC P0105: MANIFOLD ABSOLUTE PRESSURE SENSOR in DIAGNOSTIC TESTS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article.
  5. Check the crankcase ventilation system for proper operation.
  6. Use a scan tool to monitor the Knock Sensor (KS) system for excessive spark retard activity.
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