Mitsubishi Lancer Evolution X. Manual - part 287

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-213

CIRCUIT OPERATION

• 5-volt voltage is applied to the engine coolant 

temperature sensor output terminal (terminal No. 
1) from the ECM (terminal No. 26) via the resistor 
in the ECM. The ground terminal (terminal No. 2) 
is grounded with ECM (terminal No. 27).

• The engine coolant temperature sensor is a neg-

ative temperature coefficient type of resistor. It 
has the characteristic that when the engine cool-
ant temperature rises the resistance decreases.

• The engine coolant temperature sensor output 

voltage increases when the resistance increases 
and decreases when the resistance decreases.

.

TECHNICAL DESCRIPTION

• The engine coolant temperature sensor converts 

the engine coolant temperature to a voltage and 
outputs it.

• The ECM checks whether this voltage is within a 

specified range.

.

DESCRIPTIONS OF MONITOR METHODS

• Engine coolant temperature sensor output volt-

age drops from over 40° C (104° F) to under 40° C 

(104° F) and keeps under 40° C (104° F) for 5 

minutes.

• Engine coolant temperature sensor output volt-

age does not reach close loop enable tempera-
ture within specified period when engine coolant 
temperature sensor output voltage at engine start 
is under 7° C (45° F).

.

MONITOR EXECUTION

Continuous

.

MONITOR EXECUTION CONDITIONS 
(Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor
• Intake air temperature sensor

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-214

DTC SET CONDITIONS <Range/Performance problem − drift>

Logic Flow Chart

.

Check Conditions, Judgement Criteria

• Engine coolant temperature decreases from 

higher than 40° C (104° F) to lower than 40° C 

(104° F).

• Then the engine coolant temperature is lower 

than 40° C (104° F) for 5 minutes.

• However, time is not counted when fuel is shut 

off.

.

End

No

No

Malfunction

Good

300secs have passed 

without fuel cut?

No

 

Over 40˚C (104˚F)

Over 40˚C (104˚F)

Under 40˚C (104˚F)

No

AK900355

Start

Yes

Yes

Yes

Yes

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-215

DTC SET CONDITIONS <Range/Performance problem − low input (Time to reach 
closed loop temperature)>

Logic Flow Chart

Check Conditions, Judgement Criteria

• About 90 − 300 seconds have passed for the 

engine coolant temperature to rise to about 7° C 

(45° F) after starting sequence was completed.

• However, time is not counted when fuel is shut 

off.

.

FAIL-SAFE AND BACKUP FUNCTION

• Control as if the engine coolant temperature is 80 

° C.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 8 

P.13A-9

.

TROUBLESHOOTING HINTS (The most likely 

causes for this code to be set are:)

• Engine coolant temperature sensor failed.
• Harness damage in engine coolant temperature 

sensor circuit or connector damage.

• ECM failed.

End

No

No

Malfunction

Good

Specified time 

has passed without fuel cut after 

engine start?

Engine

coolant

temp.

Closed loop

enable temp.

>

No

AK900354

Start

Yes

Yes

Yes

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-216

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

STEP 1. Using scan tool MB991958, check data list item 6: 
Engine Coolant Temperature Sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode for item 

6, Engine Coolant Temperature Sensor.

• The engine coolant temperature and temperature 

shown with the scan tool should approximately match.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points − How to 

Cope with Intermittent Malfunctions 

P.00-15

.

NO :  Go to Step 2.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB