Mitsubishi Eclipse. Manual — part 418

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-215

.

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the ECM (ter-
minal No. 72) <M/T> or PCM (terminal No. 72)
<A/T> from the output terminal (terminal No. 4) of
the right bank heated oxygen sensor (front).

• Terminal No. 2 of the right bank heated oxygen

sensor (front) is grounded with ECM (terminal
No. 49) <M/T> or PCM (terminal No. 57) <A/T>.

.

TECHNICAL DESCRIPTION

• The right bank heated oxygen sensor (front)

detects the concentration of oxygen in the
exhaust gas; it converts those data to voltage,
and inputs the resulting signals to the ECM
<M/T> or PCM <A/T>.

• When the right bank heated oxygen sensor

(front) begins to deteriorate, the heated oxygen
sensor signal response becomes poor.

• The ECM <M/T> or PCM <A/T> forcibly varies

the air/fuel mixture to make it leaner and richer,
and checks the response speed of the right bank
heated oxygen sensor (front). In addition, the
ECM <M/T> or PCM <A/T> also checks for an
open circuit in the right bank heated oxygen sen-
sor (front) output line.

.

DESCRIPTIONS OF MONITOR METHODS
Right bank heated oxygen sensor (front) circuit is

switched to 5 volts intentionally when oxygen
sensor output is low, and detects the malfunction
if the output voltage changes to equal or greater
than 4.5 volts. The above procedure is repeated
when oxygen sensor is inactive.

.

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)

• Heated oxygen sensor heater (front) monitor

• Misfire monitor

• Fuel system monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.

AK300057

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AB

B-27 (B)

CONNECTOR: B-27

AK300244

CONNECTORS: C-55, C-59 <A/T>

AD

PCM

C-55 (GR)

C-59 (GR)

AK300091

CONNECTORS: C-58, C-62 <M/T>

ECM

AD

C-58 (GR)

C-62 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-216

Logic Flow Chart

.

Check Conditions

• 3 minutes or more have passed since the starting

sequence was completed.

• Right bank heated oxygen sensor (front) signal

voltage has continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Monitoring time: 7 seconds.

Judgment Criteria

• Input voltage supplied to the ECM <M/T> or PCM

<A/T> interface circuit is higher than 4.5 volts
when 5 volts is applied to the right bank heated
oxygen sensor (front) output line via a resistor.

.

START

V

F

> =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK301436

V

F

< 0.2V

10secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-217

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: )

• Right bank heated oxygen sensor (front) deterio-

rated.

• Open or shorted circuit in right bank heated oxy-

gen sensor (front) output line or harness damage.

• Open circuit in right bank heated oxygen sensor

(front) ground line or harness 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

• MD998464: Test Harness

STEP 1. Using scan tool MB991958, check data list item 39:
Heated Oxygen Sensor Bank 1, Sensor 1 (right front).

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

39, Heated Oxygen Sensor Bank 1, Sensor 1 (right front).

• Warming up the engine. When the engine is revved, the

output voltage should be 0.6 to 1.0 volt.

• Warming up the engine. When the engine is idling, the

output voltage should repeat 0.4 volt and 0.6 to 1.0 volt
alternately.

(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

P.00-6

.

NO : Go to Step 2.

AK300810

AB

MB991911

16-PIN

MB991827

MB991824

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-218

STEP 2. Check the sensor output voltage at right bank
heated oxygen sensor (front) connector B-27 by
backprobing.
(1) Do not disconnect the connector B-27.
(2) Start the engine and run at idle.

(3) Measure the voltage between terminal No. 4 and ground by

backprobing.

• Warming up the engine. When the engine is 2,500 r/min,

the output voltage should repeat 0 to 0.8 volt alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?

YES : Go to Step 3.
NO : Go to Step 7.

AK300409

1

2

3

4

RIGHT BANK
HEATED OXYGEN
SENSOR (FRONT)

AB

B-27 (B)

CONNECTOR: B-27

HARNESS CONNECTOR:
COMPONENT SIDE

AKX01541AR

1 2
3 4

B-27 HARNESS
CONNECTOR:
HARNESS SIDE