Mitsubishi FUEL Manual page 278

13I-84
INSPECTION PROCEDURE 18
Too high CO and HC concentration when idling
The cause is probably an incorrect air/fuel ratio
MUT-II Self-Diag code
Is a diagnosis code displayed?
Check ignition timing. (Refer to GROUP 11D - Engine Adjustment.)
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13I-98.)
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13I-98.)
MUT-II Data list
25 Barometric pressure sensor (Refer to P.13I-98.)
MUT-II Data list
59 Oxygen sensor (rear)
D Transmission: 2nd gear <M/T>, L range <A/T>
D Driving with throttle widely open
OK: 600 - 1,000 mV
MUT-II Data list
11 Oxygen sensor (front)
OK: 600 - 1,000 mV when the engine is suddenly raced
MUT-II Data list
11 Oxygen sensor (front)
OK: 0 - 400 mV and 600 - 1,000 mV alternates when the
engine is idling (wait for four minutes after the engine
started).
Measure fuel high-pressure between the fuel pump (high pressure)
and injector. (Refer to P.13I-122.)
Check ignition coil spark for each cylinder.
(1) Remove the ignition coil.
(2) Install a new spark plug to the removed ignition coil.
(3) Disconnect the injector intermediate connector.
Caution
Never touch the connector terminal as approx. 100 V is applied to the injector, or you are seriously injured.
(4) Earth the spark plug electrode securely.
(5) Check that the spark plug ignites when the engine is cranked.
Check all the following items:
D Spark plug
D EGR system
D Compression pressure
D Clogged fuel filter or line
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GDI -
No
OK
OK
OK
OK
OK
OK
NG
OK
OK
OK
Troubleshooting
Probable cause
D Malfunction of air/fuel ratio control system
D Deterioration of the catalyst
Yes
(Refer to P.13I-11, INSPECTION CHART FOR DIAGNOSIS
CODES.)
NG
Check that the crank angle sensor and timing belt cover are properly
installed.
NG
Check the engine coolant temperature sensor. (Refer to P.13I-18,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE P0115.)
NG
Check the intake air temperature sensor. (Refer to P.13I-17, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE P0110.)
NG
Check the barometric pressure sensor. (Refer to P.13I-15, INSPEC-
TION PROCEDURE FOR DIAGNOSIS CODE P0105.)
NG
Check the oxygen sensor (rear) system. (Refer to P.13I-28, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE P0136.)
NG
Check the oxygen sensor (front) system. (Refer to P.13I-25, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE P0130.)
OK
Replace the oxygen sensor (front).
Check trouble symptom.
NG
Repair
Replace the ignition coil.
NG
NG