Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Geo >> 1996 >> Metro Base, 2D Hatchback, 1.3 9 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0171 - Fuel Trim System Lean >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to DLC. Start engine and allow to reach normal operating temperature. Operate vehicle while loop status on scan tool indicates CLOSED LOOP. Observe short term Fuel Trim (FT) parameter on scan tool. If display reads 0-20 percent, go to next step. If display reading is not as specified, go to step 3).
  2. Select CLEAR INFORMATION function. Operate vehicle within FREEZE FRAME conditions. Observe long and short term FT parameters and add together. If displayed values are 0-30 percent while operating vehicle within FREEZE FRAME conditions, check for an intermittent problem. See TESTS W/O CODES article. If display values are not as specified, go to next step.
  3. Inspect PCV valve for proper installation. Check exhaust system for leaks. Check EGR system for proper operation. Ensure PCM and sensors are installed properly and grounds are clean and tight. Repair as necessary. If no problems are found, go to next step.
  4. Turn ignition off. Install fuel pressure gauge. Start engine. Check fuel pressure at idle with engine at normal operating temperature. If fuel pressure is 13-20 psi (0.9-1.4 kg/cm2 ), go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST A1-7B in BASIC TESTING article.
  5. Check fuel for excessive water, alcohol, or other contaminants. Repair as necessary. If fuel is okay, check for restrictions in fuel injector. Repair as necessary. Retest system. If no problems are found and lean condition is still present, see BASIC TESTING article.
scientia non olet · About Mike's Workshop Manuals