Mitsubishi Lancer Evolution X. Manual - part 381

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-589

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, read the diagnostic 
trouble code (DTC).

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) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the diagnostic trouble code other than P1238 set?

YES : Refer to, Diagnostic Trouble Code Chart 

P.13A-48

. 

NO :  Go to Step 2. 

STEP 2. Using scan tool MB991958, check data list item 10: 
Mass Airflow Sensor.
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item 

10, Mass Airflow Sensor.

(3) Warm up the engine to normal operating temperature: 80° C 

to 95° C (176° F to 203° F).

• The standard value during idling should be between 

1,350 and 1,670 millivolts.

• When the engine is revved, the mass airflow rate should 

increase according to the increase in engine speed.

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

YES : Go to Step 3.
NO :  Refer to, DTC P0101 − Mass Airflow Circuit 

Range/Performance Problem 

P.13A-126

, DTC P0102 

− Mass Airflow Circuit Low Input 

P.13A-132

, DTC 

P0103 − Mass Airflow Circuit High Input 

P.13A-139

.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-590

STEP 3. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function − OBD-II Drive Cycle − Pattern 16 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P1238 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-11

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 4.

NO :  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

. 

STEP 4. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function − OBD-II Drive Cycle − Pattern 16 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P1238 set?

YES : Retry the troubleshooting.
NO :  The inspection is complete.

DTC P1239: Engine RPM Plausibility

.

TECHNICAL DESCRIPTION

Compares the actual engine speed calculated from 
the crankshaft position sensor signal cycle with the 
estimated engine speed calculated from the number 
of the crankshaft position sensor signal pulses after a 
lapse of the specified time.

.

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)

• Not applicable

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-591

DTC SET CONDITIONS

Logic Flow Chart

Check Condition

• The engine speed monitored with a 180 degree- 

cycle pulse is 500 r/min or more.

Judgment Criterion

• The difference between the engine speed moni-

tored with a 180 degree-cycle pulse and the 
engine speed monitored with a 10 degree-cycle 
pulse is 500 r/min or more.

Check Condition

• The engine speed monitored with a 180 degree- 

cycle pulse is 500 r/min or less.

Judgment Criterion

• The engine speed monitored with a 10 degree- 

cycle pulse is 1,000 r/min or more.

.

FAIL-SAFE AND BACKUP FUNCTION

• Throttle opening degree position is in default 

position.

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 23 

P.13A-9

.

.

TROUBLESHOOTING HINTS (The most 
likely causes for this code to be set are:)

• Crankshaft position sensor system failed.
• ECM failed.

AK604355

Start

End

No

No

No

Yes

Yes

Yes

Yes

No

Malfunction

Good

|Ne (180˚)-Ne (10˚)|

>= 500r/min

Ne (180˚) >= 500r/min

Ne (10˚) > 1000r/min

Continuous

failure for 0.5sec

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-592

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, read the diagnostic 
trouble code (DTC).

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) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the diagnostic trouble code other than P1239 set?

YES : Refer to, Diagnostic Trouble Code Chart 

P.13A-48

. 

NO :  Go to Step 2. 

STEP 2. Using scan tool MB991958, read the diagnostic 
trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the DTC has been deleted, read the DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1239 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-11

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 3.

NO :  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

. 

AC608435

Data link connector

MB991827

MB991824

MB991910

AB