Infiniti F50. Manual - part 414

DTC P0300 - P0308 NO. 8 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MIS-

FIRE

EC-297

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DTC P0300 - P0308 NO. 8 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MIS-
FIRE

PFP:00020

On Board Diagnosis Logic

EBS00MDG

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crank-
shaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.

The misfire detection logic consists of the following two conditions.

1.

One Trip Detection Logic (Three Way Catalyst Damage)
On the first trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to over-
heating, the MIL will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions
for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.
If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on.
If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.

2.

Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only
light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sen-
sor signal every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.

Sensor

Input Signal to ECM

ECM function

Crankshaft position sensor (POS)

Engine speed

On board diagnosis of misfire

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0300
0300

Multiple cylinder misfire 
detected

Multiple cylinder misfire.

●

Improper spark plug

●

Insufficient compression

●

Incorrect fuel pressure

●

The injector circuit is open or shorted

●

Fuel injectors

●

Intake air leak

●

The ignition signal circuit is open or 
shorted

●

Lack of fuel

●

Drive plate

●

Heated oxygen sensor 1

●

Incorrect PCV hose connection

P0301
0301

No.1 cylinder misfire 
detected

No. 1 cylinder misfires.

P0302
0302

No. 2 cylinder misfire 
detected

No. 2 cylinder misfires.

P0303
0303

No. 3 cylinder misfire 
detected

No. 3 cylinder misfires.

P0304
0304

No. 4 cylinder misfire 
detected

No. 4 cylinder misfires.

P0305
0305

No. 5 cylinder misfire 
detected

No. 5 cylinder misfires.

P0306
0306

No. 6 cylinder misfire 
detected

No. 6 cylinder misfires.

P0307
0307

No. 7 cylinder misfire 
detected

No. 7 cylinder misfires.

P0308
0308

No. 8 cylinder misfire 
detected

No. 8 cylinder misfires.

EC-298

DTC P0300 - P0308 NO. 8 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MIS-

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DTC Confirmation Procedure

EBS00MDH

CAUTION:

Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driv-
ing.

NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.

 WITH CONSULT-II

1.

Turn ignition switch ON, and select “DATA MONITOR” mode
with CONSULT-II.

2.

Start engine and warm it up to normal operating temperature.

3.

Turn ignition switch OFF and wait at least 10 seconds.

4.

Restart engine and let it idle for about 15 minutes.

5.

If 1st trip DTC is detected, go to 

EC-298, "Diagnostic Procedure"

.

NOTE:
If 1st trip DTC is not detected during above procedure, performing
the following procedure is advised.

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Start engine and drive the vehicle under the similar conditions to (1st trip) Freeze Frame Data for a certain
time. Refer to the table below.
Hold the accelerator pedal as steady as possible.

The similar conditions to (1st trip) Freeze Frame Data means the vehicle operation that the following con-
ditions should be satisfied at the same time.

The time to driving varies according to the engine speed in the freeze frame data.

 WITH GST

Follow the procedure “With CONSULT-II” above.

Diagnostic Procedure

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1. 

CHECK FOR INTAKE AIR LEAK

1.

Start engine and run it at idle speed.

2.

Listen for the sound of the intake air leak.

OK or NG

OK

>> GO TO 2.

NG

>> Discover air leak location and repair.

PBIB0164E

Engine speed

Engine speed in the freeze frame data 

±

 400 rpm

Vehicle speed

Vehicle speed in the feaze frame data 

±

 10 km/h (6 MPH)

Engine coolant temperature 
(T) condition

When the freeze frame data shows lower than 70 

°

C (158 

°

F),

T should be lower than 70 

°

C (158 

°

F).

When the freeze frame data shows higher than or equal to 70 

°

C (158 

°

F),

T should be higher than or equal to 70 

°

C (158 

°

F).

Engine speed

Time 

Around 1,000 rpm

Approximately 10 minutes

Around 2,000 rpm

Approximately 5 minutes

More than 3,000 rpm

Approximately 3.5 minutes

DTC P0300 - P0308 NO. 8 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MIS-

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EC-299

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2. 

CHECK FOR EXHAUST SYSTEM CLOGGING

Stop engine and visually check exhaust tube, three way catalyst (manifold) and muffler for dents.

OK or NG

OK

>> GO TO 3.

NG

>> Repair or replace it.

3. 

PERFORM POWER BALANCE TEST

 With CONSULT-II

1.

Perform “POWER BALANCE” in “ACTIVE TEST” mode.

2.

Is there any cylinder which does not produce a momentary
engine speed drop?

 Without CONSULT-II

When disconnecting each injector harness connector one at a time, is there any cylinder which does not pro-
duce a momentary engine speed drop?

Yes or No

Yes

>> GO TO 4.

No

>> GO TO 7.

4. 

CHECK INJECTOR

Does each injector make an operating sound at idle?

Yes or No

Yes

>> GO TO 5.

No

>> Check injector(s) and circuit(s). Refer to 

EC-653,

"INJECTOR CIRCUIT"

 .

PBIB0133E

PBIB1247E

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EC-300

DTC P0300 - P0308 NO. 8 - 1 CYLINDER MISFIRE, MULTIPLE CYLINDER MIS-

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5. 

CHECK IGNITION SPARK

1.

Disconnect ignition wire from spark plug.

2.

Connect a known-good spark plug to the ignition wire.

3.

Disconnect all injector harness connectors.

4.

Place end of spark plug against a suitable ground and crank engine.

5.

Check for spark.

OK or NG

OK

>> GO TO 6.

NG

>> Check ignition coil, power transistor and their circuits.

Refer to 

EC-641, "IGNITION SIGNAL"

 .

6. 

CHECK SPARK PLUGS

Remove the spark plugs and check for fouling, etc.

OK or NG

OK

>> GO TO 7.

NG

>> Repair or replace spark plug(s) with standard type

one(s). For spark plug type, refer to, 

MA-18, "Changing

Spark Plugs (Platinum-Tipped Type)"

 .

7. 

CHECK COMPRESSION PRESSURE

Check compression pressure. Refer to 

EM-61, "CHECKING COMPRESSION PRESSURE"

 ,.

OK or NG

OK

>> GO TO 8.

NG

>> Check pistons, piston rings, valves, valve seats and cylinder head gaskets.

8. 

CHECK FUEL PRESSURE

1.

Install all removed parts.

2.

Release fuel pressure to zero. Refer to 

EC-48, "FUEL PRESSURE RELEASE"

 .

3.

Install fuel pressure gauge and check fuel pressure. Refer to 

EC-49, "FUEL PRESSURE CHECK"

 .

OK or NG

OK

>> GO TO 10.

NG

>> GO TO 9.

SEF575Q

SEF156I

Standard:

1,320 kPa (13.5 kg/cm

2

 , 191 psi)/300 rpm

Minimum:

1,130 kPa (11.5 kg/cm

2

 , 164 psi)/300 rpm

Difference between each 
cylinder:

98 kPa (1.0 kg/cm

2

 , 14 psi)/300 rpm

At idle:

Approx. 350 kPa (3.57 kg/cm

2

 , 51 psi)