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Home >> Chevrolet >> 2003 >> Tracker 2D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 2.0L >> Diagnostic Tests >> DTC P0171: Lean Fuel Trim System >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Start engine. Allow the engine to reach a normal operating temperature. Operate the vehicle until the scan tool indicates Closed Loop. Observe the Short Term FT parameter on the scan tool. Is the scan tool display less than 15%? If yes, go to next step. If no, go to  4.
  3. Turn ignition on, with engine off. Perform the scan tool Clear DTC Information function. Operate the vehicle within the Freeze Frame conditions as noted. Observe the Total Fuel Trim parameter on the scan tool. Was the scan tool display less than the 43% while operating the vehicle within the Freeze Frame conditions? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  4. Turn ignition off. Visually and physically check the following items:
    • Vacuum hoses for splits, kinks and improper connections.
    • PCV valve for proper installation.
    • Exhaust system for leaks near HO2S.
    • EVAP control system for proper operation.
    Repair as necessary. Did any of the checks isolate a condition requiring a repair? If yes, go to step  11. If no, go to next step.
  5. Start engine. Run the engine to normal operating temperatures. Observe the operation of the following sensors at idle, with a scan tool: The MAP sensor, ECT sensor and TP sensor. Compare the observed sensor readings with the Typical Scan Tool Data values located in the engine scan tool data list. See PID VALUE CHARTS - TRUCKS article. Inspect the vehicle for the cause of any errant sensor readings and repair as necessary. Was a repair necessary? If yes, go to step  11. If no, go to next step.
  6. Turn ignition off. Install Fuel Pressure Gauge (J-34730-1A). Start engine. Observe fuel pressure with the engine idling at normal operating temperatures. Is fuel pressure within 36-43 psi (250-300 kPa)? If yes, go to next step. If no, see FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.0L & 2.5L TRACKER article.
  7. Check fuel for excessive water, alcohol or other contaminates. Was fuel contaminated? If yes, go to next step. If no, go to step  9.
  8. Replace contaminated fuel. After repairs, go to step  11.
  9. Check fuel injectors for regular and even fuel discharge, and fuel dispersed in a conical spray pattern. Ensure injector coil resistance is within specification. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.0L & 2.5L TRACKER article. Did the fuel injectors pass all the checks? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  10. Replace faulty fuel injectors. After repairs, go to next step.
  11. Turn ignition off. Remove DOME fuse for 30 seconds (fuse is located in passenger compartment fuse block). Reinstall DOME fuse. Reset radio clock time. Start engine. Operate vehicle within the conditions for running the DTC or until DTC P0171 diagnostic test has run. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  12. Using scan tool, observe the stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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