Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement page 520

INSPECTION PROCEDURE 22
Too high CO and HC concentration when idling
Abnormal air-fuel ratio is suspected.
MUT-II Self-Diag code
Are diagnosis codes displayed?
Check the ignition timing.
(Refer to GROUP 11A – On-vehicle Service.)
MUT-II Data list
21 Engine coolant temperature sensor. (Refer to P.13B-49.)
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13B-48.)
MUT-II Data list
59 Oxygen sensor (rear) (Refer to P.13B-51.)
Transmission: 2nd gear
Driving with throttle widely open
OK: 600 – 1,000 mV
MUT-II Data list
11 Oxygen sensor (front) (Refer to P.13B-48.)
OK: 600 – 1000 mV when racing suddenly
MUT-II Data list
11 Oxygen sensor (front) (Refer to P.13B-48.)
OK: Repeat 0 – 400 mV and 600 – 1,000 mV alternately
when idling.
Check the fuel pressure. (Refer to P.13B-67.)
Check the following items.
Check the injectors for operation sound.
Check the injectors for fuel leakage.
Check the ignition coil, spark plugs, spark plug cables. (Refer to GROUP 16 – On-vehicle Service.)
Check the compression pressure. (Refer to GROUP 11A – On-vehicle Service.)
Check the positive crankcase ventilation system. (Refer to GROUP 17 – Emission Control System.)
Check the purge control system. (Refer to GROUP 17 – Emission Control System.)
Check the EGR control system. (Refer to GROUP 17 – Emission Control System.)
Check the trouble symptom.
Replace the catalytic converter.
MPI –
No
OK
OK
OK
OK
OK
NG
OK
NG
Troubleshooting
Probable cause
Malfunction of the air-fuel ratio control system
Deteriorated catalyst
Yes
Refer to P.13B-9, INSPECTION CHART FOR DIAGNOSIS
CODES.
NG
Check that the distributor is installed properly.
NG
Check the engine coolant temperature sensor system.
(Refer to P.13B-13, INSPECTION PROCEDURE FOR DIAGNO-
SIS CODE 21.)
NG
Check the intake air temperature sensor system. (Refer to
P.13B-11, INSPECTION PROCEDURE FOR DIAGNOSIS CODE
13.)
NG
Check the oxygen sensor (rear) system. (Refer to P.13B-19, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE 59.)
NG
Check the oxygen sensor (front) system. (Refer to P.13B-10, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE 11.)
OK
Replace the oxygen sensor.
Check trouble symptom.
13B-39
NG