Mitsubishi Evolution X. Manual — part 283

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-109

DTC SET CONDITIONS <Range/Performance problem

− high>

Logic Flow Chart

Check Conditions

• Throttle position sensor output voltage is 1.0 volt

or lower.

• Mass airflow sensor output voltage is 4.9 volts

(corresponding to an air flow rate of 387 g/sec) or
lower.

Judgement Criterion

• Mass airflow sensor output voltage has continued

to be 3.5 volts (corresponding to an air flow rate
of 119 g/sec) or higher for 2 seconds.

.

End

No

No

No

Malfunction

Good

Output voltage

>= 3.5V

AK604308

Start

Yes

Yes

Yes

Continuous
failure for 2secs

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-110

DTC SET CONDITIONS <Range/Performance problem

− low >

Logic Flow Chart

Check Conditions

• Engine speed is 1,500 r/min or higher.

• Throttle position sensor output voltage is 1.5 volts

or higher.

• Mass airflow sensor output voltage is 0.2 volt

(corresponding to an air flow rate of 0 g/sec) or
higher.

Judgement Criterion

• Mass airflow sensor output voltage has continued

to be 1.8 volts (corresponding to an air flow rate
of 10 g/sec) or lower for 2 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Pattern 6

P.13A-9

.

.

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

• Mass airflow sensor failed.

• Mass airflow sensor circuit harness damage, or

connector damage.

• ECM failed.

End

No

No

No

Malfunction

Good

Output voltage

<= 1.8V

AK604309

Start

Yes

Yes

Yes

Continuous
failure for 2secs

Monitoring
conditions

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-111

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).

• The standard value during idling should be between

1,300 and 1,650 millivolts.

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

increase according to the increase in engine speed.

(5) 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.

STEP 2. Check harness connector A-07 at mass airflow
sensor and harness connector A-34X at MFI relay for
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 8.

STEP 3. Check for harness damage between MFI relay
connector A-34X (terminal No. 2) and mass airflow sensor
connector A-07 (terminal No. 2).
Q: Is the harness wire in good condition?

YES : Go to Step 4.
NO : Repair it. Then go to Step 8.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-112

STEP 4. Check harness connector B-10 at ECM for
damage.
Q: Is the harness connector in good condition?

YES : Go to Step 5.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 8.

STEP 5. Check the continuity at mass airflow sensor
harness side connector A-07.
(1) Disconnect the connector A-07 and measure at the harness

side.

(2) Check for the continuity between terminal No. 4 and

ground.

• Continuity (2 ohms or less)

Q: Does continuity exist?

YES : Go to Step 6.
NO : Repair harness wire between mass airflow sensor

connector A-07 (terminal No. 4) and ECM connector
B-10 (terminal No. 88) because of harness damage.
Then go to Step 8.

STEP 6. Check for harness damage between mass airflow
sensor connector A-07 (terminal No. 3) and ECM connector
B-10 (terminal No. 87).
Q: Is the harness wire in good condition?

YES : Go to Step 7.
NO : Repair it. Then go to Step 8.

STEP 7. Replace the mass airflow sensor.
(1) Replace the mass airflow sensor.
(2) Carry out a test drive with the drive cycle pattern. Refer to

Diagnostic Function

− OBD-II Drive Cycle − Pattern 6

P.13A-9

.

(3) Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 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-12

or GROUP 42C, ID Codes

Registration Judgment Table <Vehicles with WCM>

P.42C-9

. Then go to Step 8.

NO : The inspection is complete.

STEP 8. 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 6

P.13A-9

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0101 set?

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

AK704236

2 1

3

4

A-07 harness
connector:
component side

AB