Diagnostic Aids
WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport and 2002 Isuzu Rodeo. However, it is still accessible from the selected car via links, so may be relevant.
Scan tool message MISFIRE CUR. #1-4 is helpful for determining if only a single cylinder is affected by misfire. If scan tool displays MISFIRE CUR. #1-4, inspect ignition coil for cracks or damage. If problem is present, substitute a known-good ignition coil, or swap ignition coils cylinder-to-cylinder. If misfire follows coil, replace suspect ignition coil.
If misfire is random check following:
- Check PCM and system grounds. Ensure that all grounds are clean and secure. See WIRING DIAGRAMS article.
- Check MAF sensor. See SYSTEM & COMPONENT TESTING article.
- Check for disconnected or damaged vacuum hoses. Incorrectly installed or faulty PCV valve. Check for vacuum leaks at EGR valve, throttle body and intake manifold.
- Perform FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article. Check for faulty fuel pump, plugged fuel filter or suspect fuel pressure regulator.
- Check fuel injectors. Perform FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. Also check condition of fuel injector "O" ring seals.
- Check EGR valve. Check for leaking valve, adapter and feed pipes. See SYSTEM & COMPONENT TESTING article.
- Check fuel quality. Fuel with wrong octane rating may cause driveability issues.
- Excessive engine vibration may falsely set DTC P0300.