Mitsubishi Lancer Evolution X. Manual - part 302

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-273

STEP 13. Replace the injector.
(1) Replace the injector.
(2) Carry out a test drive with the drive cycle pattern. Refer to 

Diagnostic Function − OBD-II Drive Cycle − Pattern 21 

P.13A-9

.

(3) Check the diagnostic trouble code (DTC).
Q: Is DTC P0171 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 14.

NO :  The inspection is complete.

STEP 14. 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 21 

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is the DTC P0171 set?

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

DTC P0172: System too Rich

.

Fuel Trim Circuit

• Refer to DTC P0201 − Injector Circuit-Cylinder 1 

P.13A-298

, DTC P0202 − Injector Circuit-Cylinder 

2 

P.13A-308

, DTC P0203 − Injector Circuit-Cylin-

der 3 

P.13A-318

, DTC P0204 − Injector Cir-

cuit-Cylinder 4 

P.13A-328

.

.

CIRCUIT OPERATION

• Refer to DTC P0201 − Injector Circuit-Cylinder 1 

P.13A-298

, DTC P0202 − Injector Circuit-Cylinder 

2 

P.13A-308

, DTC P0203 − Injector Circuit-Cylin-

der 3 

P.13A-318

, DTC P0204 − Injector Cir-

cuit-Cylinder 4 

P.13A-328

.

.

TECHNICAL DESCRIPTION

• If a malfunction occurs in the fuel system, the fuel 

trim value becomes too small.

• The ECM checks whether the fuel trim value is 

within a specified range.

.

DESCRIPTIONS OF MONITOR METHODS

Air/fuel learning value (long time fuel trim) and 

air/fuel feedback integral value (short time fuel 
trim) are too rich.

.

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)

• Misfire monitor

Sensor (The sensor below is determined to be 

normal)

• Mass airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
• Throttle position sensor

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-274

DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• Under the closed loop air/fuel ratio control.
• Engine coolant temperature is higher than 76° C 

(169° F).

• Mass airflow sensor output is 13 g/sec or more.

Judgement Criterion

• Long-term fuel trim has continued to be −12.5 per-

cent or lower for 5 seconds.

or

• Short-term fuel trim has continued to be −10.2 

percent or lower for 5 seconds.

Check Conditions

• Under the closed loop air/fuel ratio control.
• Engine coolant temperature is higher than 76° C 

(169° F).

• Mass airflow sensor output is less than 13 g/sec.

Judgement Criterion

• Long-term fuel trim has continued to be −12.5 per-

cent or lower for 5 seconds.

or

• Short-term fuel trim has continued to be −15.2 

percent or lower for 5 seconds.

End

No

No

No

No

No

No

Malfunction

Good

AK604328

Start

Yes

Yes

Yes

Yes

Yes

Yes

Continuous

failure for 5secs

Monitoring
conditions

K

LRN

 >= K0

K

LRN

 <= K2

K

I

 >= K1

K

I

 <= K3

K

LRN

: Long-term trim

K

I      

: Short-term trim

K0   : Maximum limit of long-term trim

K2   : Minimum limit of long-term trim

K1   : Maximum limit of short-term trim

K3   : Minimum limit of short-term trim

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-275

Check Conditions

• Engine coolant temperature is higher than 76° C 

(169° F).

• Under the closed loop air/fuel ratio control.

Judgement Criteria

• Long-term fuel trim has continued to be −12.5 per-

cent for 2 seconds.

or

• Short-term fuel trim has continued to be −

 25.0 

percent for 2 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 21 

P.13A-9

.

.

TROUBLESHOOTING HINTS (The most likely 

causes for this code to be set are:)

• Mass airflow sensor failed.
• Injector failed.
• Incorrect fuel pressure.
• Engine coolant temperature sensor failed.
• Intake air temperature sensor failed.
• Barometric pressure sensor failed.
• Manifold absolute pressure sensor failed.
• ECM failed.

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 10: 
Mass Airflow 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) Start the engine and run at idle.
(3) Set scan tool MB991958 to the data reading mode for item 

10, Mass Airflow Sensor.

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

to 95° C (176° F to 203° F).

• When idling, between 1,300 and 1,650 millivolts.
• When 2,500 r/min, between 1,620 and 2,100 millivolts.

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

YES : Go to Step 2.
NO :  Refer to DTC P0101 − Mass Airflow Circuit 

Range/Performance Problem (sensor 1) 

P.13A-126

, 

DTC P0102 − Mass Airflow Circuit Low Input (sensor 

1) 

P.13A-132

, DTC P0103 − Mass Airflow Circuit High 

Input (sensor 1) 

P.13A-139

.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-276

STEP 2. Using scan tool MB991958, check data list item 5: 
Intake Air Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 

5, Intake Air Temperature Sensor.

• The intake air temperature and temperature shown with 

the scan tool should approximately match.

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

YES : Go to Step 3.
NO :  Refer to DTC P0111 − Intake Air Temperature Circuit 

Range/Performance Problem 

P.13A-166

, DTC P0112 

− Intake Air Temperature Circuit Low Input 

P.13A-172

, 

DTC P0113 − Intake Air Temperature Circuit High 

Input 

P.13A-176

.

STEP 3. Using scan tool MB991958, check data list item 6: 
Engine Coolant Temperature Sensor.
(1) Turn the ignition switch to the "ON" position.
(2) 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.

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

YES : Go to Step 4.
NO :  Refer to DTC P0116 − Engine Coolant Temperature 

Circuit Range/Performance Problem

P.13A-182

, DTC 

P0117 − Engine Coolant Temperature Circuit Low 

Input 

P.13A-188

, DTC P0118 − Engine Coolant 

Temperature Circuit High Input 

P.13A-193

.