Mitsubishi Eclipse. Manual - part 372

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-31

CIRCUIT OPERATION

• The volume airflow sensor power is supplied from

the MFI relay (terminal No. 4), and the ground is
provided on the ECM (terminal No. 34) <M/T> or
PCM (terminal No. 16) <A/T>.

• 5-volt power is applied to the volume airflow sen-

sor output terminal (terminal No. 3) from the ECM
(terminal No. 61) <M/T> or PCM (terminal No. 65)
<A/T>. The volume airflow sensor generates a
pulse signal when the output terminal and ground
are opened/closed (opened/short).

• 6-9 volts power is applied to the PCM (terminal

No. 19) from the volume airflow sensor (terminal
No. 7).

• The PCM (terminal No. 19) controls the airflow

sensror reset signal by turning the power transis-
tor within the PCM to "ON" and "OFF" position.

TECHNICAL DESCRIPTION

• While the engine is running, the volume airflow

sensor outputs a pulse signal which corresponds
to the volume of air flow.

• The ECM <M/T> or PCM <A/T> checks whether

the frequency of this signal output by the volume
airflow sensor while the engine is running is at or
above the set value.

• When the throttle position sensor output voltage

is low, the ECM <M/T> or PCM <A/T> causes the
power transistor to be "ON" to send an volume
airflow sensor reset signal to the volume airflow
sensor. In response to the reset signal, the vol-
ume airflow sensor resets the filter circuit and
improves the ability of the volume airflow sensor
to measure the amount of air in a small air intake
region.

DESCRIPTIONS OF MONITOR METHODS
Compare load value with volume airflow sensor out-

put voltage.

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)

• Throttle position sensor

AK300121

MFI RELAY

CONNECTOR: A-18X

A-18X

AK300053

CONNECTOR: B-14

VOLUME AIRFLOW
SENSOR

B-14 (B)

AK300091

CONNECTORS: C-51, C-58 <M/T>

ECM

C-51 (GR)

C-58 (GR)

AK300244

CONNECTORS: C-52, C-55 <A/T>

PCM

C-52 (GR)

C-55 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-32

DTC SET CONDITIONS <Range/Performance problem - high input>

Logic Flow Chart

Check Conditions

• Throttle position sensor output voltage is 1.5 volts

or higher.

• Engine speed is higher than 2,000 r/min.

Judgement Criteria

• Volume airflow sensor output frequency has con-

tinued to be 60 Hz or lower for 2 seconds.

START

MONITORING

CONDITIONS

END

YES

MALFUNCTION

GOOD

OUTPUT FREQUENCY

> =800Hz

CONTINUOUS

FAILURE FOR 2 secs

AK301411

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-33

DTC SET CONDITIONS <Range/Performance problem - low input>

Logic Flow Chart

Check Conditions

• Throttle position sensor output voltage is 2 volts

or lower.

• Engine speed is lower than 2,000 r/min.

Judgement Criteria

• Volume airflow sensor output frequency has con-

tinued to be 800 Hz or higher for 2 seconds.

OBD-ll DRIVE CYCLE PATTERN
Refer to, Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 6

− Other Monitor

P.13B-7

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

• Volume airflow sensor failed.

• Open or shorted volume airflow sensor circuit,

harness damage, or connector damage.

• ECM failed. <M/T>

• PCM failed. <A/T>

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

START

MONITORING

CONDITIONS

END

YES

MALFUNCTION

GOOD

OUTPUT FREQUENCY

< =60Hz

CONTINUOUS

FAILURE FOR 2 secs

AK301412

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-34

STEP 1. Using scan tool MB991958, check data list item 12:
Volume 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

12, Volume Airflow Sensor.

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

°C

to 96

°C (176°F to 205°F).

• The standard value during idling should be 10 Hz or

more.

• When the engine is revved, the frequency 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

P.00-6

NO : Go to Step 2.

STEP 2. Check the reset signal voltage at volume airflow
sensor connector B-14 by backprobing.
(1) Do not disconnect the connector B-14.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 7 and ground by

backprobing.

• Voltage should be between 6.0 and 9.0 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 6.0 and 9.0 volts?

YES : Go to Step 5.
NO : Go to Step 3.

AK300810

MB991911

16-PIN

MB991827

MB991824

AK300078

CONNECTOR: B-14

B-14 (B)

HARNESS
CONNECTOR:
COMPONENT SIDE

AKX01515 AG

B-14 HARNESS
CONNECTOR:
HARNESS SIDE

1 2 3 4 5 6 7

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