MPI – Troubleshooting
13-34
INSPECTION PROCEDURE 22
Too high CO and HC concentration when idling
Probable cause
Abnormal air-fuel ratio is suspected. D Malfunction of the air-fuel ratio control system
D Deteriorated catalyst
Check trouble symptom.
No
Check the ignition timing.
(Refer to GROUP 11 – Engine Adjustments.)*
NG
Check that the crank angle sensor and the timing belt cover are
installed properly.
OK
MUT-II Data list
21 Engine coolant temperature sensor. (Refer to P.13-57.)
NG
Check the engine coolant temperature sensor system.
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13-56.)
NG
Check the intake air temperature sensor system. (Refer to P.13-9,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 13.)
OK
MUT-II Data list
25 Barometric pressure sensor (Refer to P.13-58.)
NG
Check the barometric pressure sensor system. (Refer to P.13-14,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 25.)
OK
MUT-II Data list
11 Oxygen sensor
OK: 600–1,000 mV when racing suddenly
NG
Check the oxygen sensor system. (Refer to P.13-15, INSPECTION
PROCEDURE FOR DIAGNOSIS CODE 31.)
OK
MUT-II Data list
11 Oxygen sensor
OK: Repeat 0–400 mV and 600–1,000 mV alternately when
idling.
OK
NG
Check the fuel pressure. (Refer to P.13-30.)*
OK
NG
Check the following items.
D Check the injectors for operation sound.
D Check the injectors for fuel leakage.
D Check the ignition coil, spark plugs, spark plug cables.
D Check the compression pressure.
D Check the positive crankcase ventilation system.
D Check the evaporative emission control system.
Check the trouble symptom.
NG
Replace the catalytic converter.
Replace the oxygen sensor.
MUT-II Self-Diag code
Are diagnosis codes displayed?
Yes
Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).
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