Fuel System Checks

Determine if a rich or lean system can cause the condition. Drive the vehicle at the speed of the complaint. Monitoring the Fuel Trim may help identify the problem.
- Lean
  
  The Long Term Fuel Trim will be more than 20 percent.
- Rich
  
  The Long Term Fuel Trim will be less than -20 percent.
Check the fuel injectors. Perform the following procedures:
- Fuel Injector Coil Test. See FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C) or FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE OUTSIDE 50-95°F (10-35°C) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.
- Fuel Injector Balance Test. See FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.
Check the fuel pressure while the condition exists. See FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.