TROUBLESHOOTING 3-5
Complaint
Symptom and possible causes
Remedy
Engine runs poorly
in high speed range.
Defective engine internal/electrical parts
• Weakened valve springs
• Worn down camshafts
• Valve timing out of adjustment
• Incorrect spark plug gap
• Ignition not advanced sufficiently due to poorly
working timing advance circuit
• Defective ignition coil/plug cap
• Defective CKP sensor
• Defective ECM
• Clogged air cleaner element
• Clogged fuel hose, resulting in inadequate fuel sup-
ply to injector
• Defective fuel pump
• Defective TP sensor
Defective air flow system
• Clogged air cleaner element
• Defective throttle valve
• Sucking air from throttle body joint or intake pipe
• Defective ECM
Defective control circuit or sensor
• Low fuel pressure
• Defective TP sensor
• Defective CKP sensor
• Defective IAP sensor
• Defective IAT sensor
• Defective ECM
Replace
Replace
Adjust
Replace
Replace
Replace
Replace
Replace
Clean or replace
Clean and replace
Replace
Replace
Clean or replace
Adjust or replace
Retighten or replace
Replace
Repair or replace
Replace
Replace
Replace
Replace
Replace