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Home >> Chevrolet >> 2000 >> Tracker 4D Utility, 4WD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0171: Fuel Trim System - Lean (1.6L) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Install scan tool. Start engine. Operate vehicle while loop status indicates CLOSED LOOP. Observe short term fuel trim parameter on scan tool. If scan tool displays 20 percent, go to next step. If scan tool does not display 20 percent, go to step  4.
  3. Turn ignition on, with engine off. Using scan tool, perform clear information function. Operate vehicle within FREEZE FRAME conditions. Observe total fuel trim parameter on scan tool. If scan tool displays less than 43 percent, go to DIAGNOSTIC AIDS . If scan tool displays 43 percent or greater, go to next step.
  4. Visually and physically check the following items:
    • Vacuum hoses for splits, kinks and improper connections.
    • PCV valve for proper installation.
    • Exhaust system for leaks.
    • EGR for proper operation.
    Repair as necessary. After repairs, go to step  11. If no problem(s) exists, go to next step.
  5. Start engine. Warm engine to normal operating temperature. Using scan tool, observe operation of MAP sensor, ECT sensor and TP sensor at idle. Compare sensor readings with scan tool typical data values. Inspect vehicle for cause of any erratic readings. Repair as necessary. After repairs, go to step  11. If no problem(s) exists, go to next step.
  6. Turn ignition off. Install fuel pressure gauge. Start engine. Warm engine to normal operating temperature. Observe fuel pressure at an idle. If fuel pressure is 30-37 psi (2.1-2.6 kg/cm2 ), go to next step. If fuel pressure is not 30-37 psi (2.1-2.6 kg/cm2 ), diagnose fuel system as necessary. See FUEL SYSTEM in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  7. Check fuel for excessive water, alcohol or other contaminates. If fuel is contaminated, go to next step. If fuel is not contaminated, go to step  9.
  8. Replace contaminated fuel. After repairs, go to step  11.
  9. Check fuel injectors for clogging or other restrictions. Replace as necessary. After repairs, go to step  11. If fuel injectors are okay, go to next step.
    10. NOTE: Before replacing HO2S No. 1, inspect sensor for contamination. If contamination is present, determine cause and repair before installing new HO2S No. 1.
  10. Remove HO2S No. 1. Check HO2S No. 1 for damage or contamination. Replace as necessary. After repairs, go to next step. If HO2S No. 1 is not damaged or contaminated, repair by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.
  11. After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
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