目录.p65

Engine mechanism - Engine assembly

CO HC Trouble occurrence Possible causes

28

Normal High Unstable idle speed

Low High Unstable idle speed

(HC readings not stable)

High High Unstable idle speed

(black smoke emission)

1. Ignition system malfunction
   Ignition timing incorrect
   Spark plug too dirty, short circuit or clearance
   incorrect


2. Valve clearance incorrect


3. Air inlet and exhaust valve leaky


4. Cylinder leaky


5. Vacuum leak:
   PCV hose
   Intake manifold
   Throttle body
   Idle speed stepping motor
   Vacuum booster and pipelines


6. Fire caused by too thin mixing ratio


7. Air filter core blocked


8. PCV valve blocked


9. EFI system malfunction
   Fuel pressure regulator malfunction
   Water temperature sensor malfunction
   Intake pressure sensor malfunction
   ECU malfunction
   Injection nozzle malfunction
   Throttle position sensor malfunction