Infiniti Q45. Manual - part 429

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

FIRE

EC-355

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

PFP:00000

On Board Diagnosis Logic

NBS001W0

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 fuel injector circuit is open or 
shorted

●

Fuel injector

●

Intake air leak

●

The ignition signal circuit is open or 
shorted

●

Lack of fuel

●

Drive plate

●

A/F 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-356

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

FIRE

DTC Confirmation Procedure

NBS001W1

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-357, "Diagnostic Procedure"

.

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

a.

Turn ignition switch OFF and wait at least 10 seconds.

b.

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.

PBIB0164E

Engine speed

Engine speed in the freeze frame data 

±

 400 rpm

Vehicle speed

Vehicle speed in the freeze 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 MULTIPLE CYLINDER MISFIRE, NO. 1 - 8 CYLINDER MIS-

FIRE

EC-357

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Diagnostic Procedure

NBS001W2

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.

3.

Check PCV hose connection.

OK or NG

OK

>> GO TO 2.

NG

>> Discover air leak location and repair.

2. 

CHECK FOR EXHAUST SYSTEM CLOGGING

1.

Stop engine

2.

Turn ignition switch OFF

3.

Visually check exhaust tube, three way catalyst (manifold) and muffler for dents.

OK or NG

OK (With CONSULT-II)>>GO TO 3.
OK (Without CONSULT-II)>>GO TO 4.
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?

Yes or No

Yes

>> GO TO 4.

No

>> GO TO 10.

PBIB0133E

EC-358

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

FIRE

4. 

CHECK FUNCTION OF FUEL INJECTOR-I

 Without CONSULT-II

1.

Turn ignition switch OFF.

2.

Disconnect harness connectors F21, F201 (bank 1) and F41, F221 (bank 2).

3.

Turn ignition switch ON.

4.

Check voltage between the following;
harness connector F21 terminal 5 and ground,
harness connector F41 terminal 5 and ground
with CONSULT-II or tester.

5.

Turn ignition switch OFF.

6.

Disconnect ECM harness connector.

7.

Check harness continuity between the following terminals.

8.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 5.

NG

>> Perform trouble diagnosis for 

EC-706, "FUEL INJECTOR"

 .

Voltage: Battery voltage

Cylinder

Harness connector terminal

ECM terminal

1

F21 terminal 3

23

3

F21 terminal 2

22

5

F21 terminal 1

21

7

F21 terminal 6

44

2

F41 terminal 3

42

4

F41 terminal 2

41

6

F41 terminal 1

40

8

F41 terminal 6

63

Continuity should exist.

PBIB2438E

PBIB0180E