Mitsubishi Galant 9G. Manual — part 1069

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-576

DTC P0302: Cylinder 2 Misfire Detected

CAUTION

If DTC P0302 has been set, TCL related DTC
U1120 is also set. After P0302 has been diag-
nosed, don't forget to erase DTC U1120.

.

TECHNICAL DESCRIPTION

• If a misfire occurs while the engine is running, the

engine speed changes for an instant.

• The PCM checks for such changes in engine

speed.

.

DESCRIPTIONS OF MONITOR METHODS

Monitor angular acceleration of crankshaft and

detect malfunction when negative variation of the
angular acceleration is large.

.

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)

• Camshaft position sensor

• Mass airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

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DTC SET CONDITIONS

Logic Flow Chart

.

START

MONITORING

CONDITIONS

CALCULATE CRANKSHAFT

ANGULAR ACCELERATION (An)

An < TH

MF

(Ne, v)

MISFIRE

CALCULATE PERCENT MISFIRE (R

MF

)

END

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

YES

GOOD

WITHIN 1000rev

R

MF

> SPECIFIED VALUE

MALFUNCTION

(EXCEED STD ×1.5)

GOOD

MALFUNCTION

(CATALYTIC CONVERTER

IS DAMAGED.)

GOOD

R

MF

> TH

CD

(Ne, v)

CALCULATE PERCENT MISFIRE (R

MF

)

WITHIN 200rev

Ne: ENGINE SPEED
v: VOLUMETRIC EFFICIENCY

AK204053

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-578

Check Conditions

• Engine speed is between 440 and 6,200 r/min.

• Engine coolant temperature is higher than −10°C

(14

°F).

• Barometric pressure is higher than 76 kPa (22.4

in.Hg).

• Volumetric efficiency is at between 30 and 60

percent.

• Adaptive learning is complete for the vane which

generates a crankshaft position signal.

• While the engine is running, excluding gear shift-

ing, deceleration, sudden acceleration/decelera-
tion and A/C compressor switching.

• The throttle deviation is −0.06 V/10 ms to +0.06

V/10 ms.

Judgement Criteria (change in the angular accel-

eration of the crankshaft is used for misfire
detection).

• Misfire has occurred more frequently than

allowed during the last 200 revolutions [when the
catalyst temperature is higher than 950

°C

(1,742

°F)].

or

• Misfire has occurred in 17 or more of the last

1,000 revolutions (corresponding to 1.5 times the
limit of emission standard).

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13B-6

.

.

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

• Ignition system related part(s) failed.

• Low compression pressure.

• PCM failed.

DIAGNOSIS

STEP 1. Check the No.2 cylinder ignition coil spark.
(1) Remove the No.2 cylinder ignition coil.
(2) Remove the No.2 cylinder spark plug and connect to the

ignition coil.

(3) Ground the No.2 cylinder spark plug side electrode

securely.

• When the engine is cranked, the spark plug should

spark.

Q: Did it spark?

YES : Go to Step 3.
NO : Go to Step 2.

AKX00432

SPARK PLUG

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-579

STEP 2. Check the No.2 cylinder spark plugs.

CAUTION

Do not attempt to adjust the gap of the iridium plug. Clean-
ing of the iridium plug may result in damage to the iridium
and platinum tips. Therefore, if carbon deposits must be
removed, use a plug cleaner and complete cleaning within
20 seconds to protect the electrode. Do not use a wire
brush.
Check the plug gap and replace if the limit is exceeded.

Standard value: 0.7

− 0.8 mm (0.028 − 0.031 inch)

Limit: 1.0 mm (0.039 inch)

Q: Is the plug gap at the standard value?

YES : Refer to, INSPECTION PROCEDURE 31

− Ignition

Circuit System

P.13B-1125

.

NO : Replace the No.2 cylinder spark plug. Then go to Step

5.

STEP 3. Check the compression.
Refer to GROUP 11C, On-Vehicle Service

− Compression

Pressure Check

P.11C-11

.

Q: Are there any abnormalities?

YES : Repair or replace it. Then go to Step 5.
NO : Go to Step 4.

STEP 4. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to

Diagnostic Function

− OBD-II Drive Cycle − Procedure 6 −

Other Monitor

P.13B-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0302 set?

YES : Replace the PCM. Then go to Step 5.
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.00-14

.

STEP 5. 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 − Procedure 6 −

Other Monitor

P.13B-6

.

(2) Check the diagnostic trouble code (DTC).
Q: Is DTC P0302 set?

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

AKX01327AB

IRIDIUM
TIP

PLATINUM
TIP