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Home >> Chevrolet >> 2001 >> Tracker 2D Utility, 4WD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0171: Lean Fuel Trim System (2.0L) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Start engine. Operate vehicle while loop status indicates CLOSED LOOP. Using scan tool, observe short term fuel trim parameter. If scan tool displays 15 percent, go to next step. If scan tool does not display 15 percent, go to step  4 .
  3. Turn ignition on, with engine off. Using scan tool, clear DTCs. 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 greater than 43 percent, 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. After repairs, go to step  11 . If problem is found, go to next step.
  5. Start and warm engine to normal operating temperature. Using scan tool, observe operation of MAP, ECT and TP sensors at idle. Compare sensor readings with scan tool typical data values. Check vehicle for cause of any erratic readings. Repair as necessary. After repairs, go to step  11 . If no problem is found, 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 36-43 psi (2.5-3.0 kg/cm2 ), go to next step. If fuel pressure is not 36-43 psi (2.5-3.0 kg/cm2 ), diagnose fuel system as necessary. See FUEL SYSTEMS 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. Turn ignition off. 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 SYSTEM in appropriate BASIC DIAGNOSTIC PROCEDURES article. If problem(s) exists, go to next step. If no problems exist, go to DIAGNOSTIC AIDS  .
  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. See CODE ENABLE CRITERIA  . If DTC runs and passes, go to next step. If DTC resets, 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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