Mazda CX-9 Grand Touring. Manual — part 256

DIAGNOSTIC PROCEDURE

DTC P0301, P0302, P0303, P0304, P0305, P0306, P0316 (MZI-3.7) DIAGNOSTIC PROCEDURE

DTC P0305

P0305: Cylinder No.5 misfire detected

DTC P0306

P0306: Cylinder No.6 misfire detected

DTC P0316

P0316: Misfire detected on startup (first 1000 revolutions)

DETECTION

CONDITION



The PCM monitors the crankshaft position sensor input signal interval time. The
PCM calculates the change of the interval time for each cylinder. If the change of
interval time exceeds the pre-programmed criteria, the PCM detects a misfire in
the corresponding cylinder, when the engine is running, the PCM counts the
number of misfires that occurred at 200 crankshaft revolutions and 1,000
crankshaft revolutions and calculates the misfire ratio for each crankshaft
revolution. If the ratio exceeds the pre-programmed criteria, the PCM determines
that a misfire, which can damage the catalytic converter or affect emission
performance, has occurred.

POSSIBLE

CAUSE



Spark plug malfunction



Ignition system malfunction



Ignition coil malfunction



Fuel injector malfunction



Air suction in intake air system (between dynamic chamber and cylinder head)



Inadequate engine compression due to engine internal malfunction



Related connector or terminal malfunction



Related wiring harness malfunction

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN
RECORDED



Has FREEZE FRAME DATA been recorded?

Yes Go to the next step.

No

Record FREEZE FRAME DATA on the

repair order, then go to the next step.

2

VERIFY RELATED REPAIR INFORMATION
AVAILABILITY



Verify related Service Bulletins and/or on-line
repair information availability.



Is any related Service Bulletins available?

Yes

Perform repair or diagnosis according to
the available Service Bulletins.



If the vehicle is not repaired, go to
the next step.

No

Go to the next step.

3

VERIFY RELATED PENDING CODE OR
STORED DTCs



Turn the ignition switch off then to the ON
position (Engine off).



Verify related pending code or stored DTCs.



Are other DTCs present?

Yes

Go to the appropriate DTC
troubleshooting. (See DTC TABLE
[MZI-3.7].)

No

Go to the next step.

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

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4

VERIFY CURRENT INPUT SIGNAL STATUS
(KEY TO ON/IDLE)



Access APP1, APP2, APP3, ECT, IAT, MAF,
RPM TP_REL and VSS PIDs using the M-
MDS. (See PCM INSPECTION [MZI-
3.7] .)



Is there any signal that is far out of
specification when the ignition switch is in
the ON position and the engine runs at idle?

Yes

Inspect the suspected circuit or part or
both according to inspection results.
Then go to Step 13. (See PCM
INSPECTION [MZI-3.7] .)

No

Go to the next step.

5

VERIFY CURRENT INPUT SIGNAL STATUS
UNDER TROUBLE CONDITION



Inspect the same PIDs as in Step 4 when
simulating the FREEZE FRAME DATA
condition.



Is there any signal which causes drastic
changes?

Yes

Inspect the suspected circuit or part or
both according inspection results. Then
go to Step 13. (See PCM INSPECTION
[MZI-3.7] .)

No

Go to the next step.

6

INSPECT SPARK PLUG CONDITION



Turn the ignition switch off.



Remove the spark plug from the suspected
cylinder.



Check the spark plug condition:



Cracks



Excess wear



Gap



Wet



Is any problem found on the spark plug?

Yes



If the spark plug is wet, fuel
flooding is suspected. Go to Step
9.



If the spark plug has a crack,
excess wear or improper gap,
replace the malfunctioning spark
plug. Then go to Step 13.

(See CRUISE CONTROL
SWITCH INSPECTION [MZI-
3.7] .)

No

Go to the next step.

7

INSPECT IGNITION SYSTEM OPERATION
FOR SUSPECTED CYLINDER



Perform the spark test for the suspected
cylinder. (See ENGINE CONTROL
SYSTEM OPERATION INSPECTION
[MZI-3.7] .)



Are the results of the spark test normal?

Yes Go to the next step.

No

Replace or replace the malfunctioning

part according to the spark test results,

then go to Step 13.

8

INSPECT FUEL INJECTOR WIRING
HARNESS



Remove the intake air system parts.



Disconnect the fuel injector connector on the
suspected cylinder.

Yes Go to the next step.

Inspect the fuel injector wiring harnesses.

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

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Sunday, November 15, 2009 10:08:36 AM

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

Connect the noid light to the fuel injector
connector terminals.



Verify the light dimness during cranking.



Does the noid light illuminate?

No

Repair or replace if necessary, then go to

Step 13.

9

INSPECT FUEL INJECTOR OPERATION



Remove fuel injector from the suspected
cylinder. (See FUEL INJECTOR
REMOVAL/INSTALLATION [MZI-3.7] .)



Swap the fuel injector with one from another
cylinder.



Start the engine and run it at idle.



Is there the misfire DTC for the cylinder
which has a suspected fuel injector?

Yes

Replace fuel injector, then go to Step 13.
(See FUEL INJECTOR
REMOVAL/INSTALLATION [MZI-
3.7] .)

No

Go to the next step.

10

INSPECT FOR AIR SUCTION AT INTAKE
AIR SYSTEM



Inspect for air leakage at the following:



Around the connection of the dynamic
chamber and the intake manifold



Around the connection of the intake
manifold and the cylinder head



Is air leakage found?

Yes

Repair or replace the suspected part, then
go to Step 13.

No

Go to the next step.

11

INSPECT SEALING OF ENGINE COOLANT
PASSAGE

WARNING:



Never remove the cooling system cap or
loosen the radiator drain plug while the
engine is running, or when the engine and
radiator are hot. Scalding engine coolant
and steam may shoot out and cause
serious injury. It may also damage the
engine and cooling system.



Turn off the engine and wait until it is cool.
Even then, be very careful when removing
the cap. Wrap a thick cloth around it and
slowly turn it counterclockwise to the first
stop. Step back while the pressure
escapes.



When you are sure all the pressure is gone,
press down on the cap using the cloth, turn
it, and remove it.

Yes

Air penetrates due to poor sealing of the
head gasket or other areas between the
combustion chamber and the engine
coolant passage. Repair or replace
malfunctioning parts, then go to Step 13.

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:36 AM

Page 159

© 2005 Mitchell Repair Information Company, LLC.

DTC P0315 [MZI-3.7]

DTC P0315 (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES



Remove the radiator cap.



Implement the procedure to bleed air from the
engine coolant, then run the engine at idle.



Are there any small bubbles which make the
engine coolant white at filling opening?

NOTE:



Large bubbles are normal since they
are remaining air coming from the
engine coolant passage.

No

Go to the next step.

12

INSPECT ENGINE COMPRESSION



Inspect the engine compression. (See
COMPRESSION INSPECTION [MZI-
3.7] .)



Is the engine compression normal?

Yes Go to the next step.

No

Overhaul the engine, then go to the next

step.

13

VERIFY TROUBLESHOOTING OF MISFIRE
DTC HAS BEEN COMPLETED



Verify that all disconnected connectors are
reconnected.



Turn the ignition switch to the ON position
(Engine off).



Clear the DTC from the PCM memory using
the M-MDS.



Start the engine and run it at idle.



Retrieve DTCs using the M-MDS.



Is the PENDING CODE for this DTC
present?

Yes

Replace the PCM, then go to the next
step. (See PCM
REMOVAL/INSTALLATION [MZI-
3.7] .)

No

Go to the next step.

14

VERIFY AFTER REPAIR PROCEDURE



Perform the "AFTER REPAIR
PROCEDURE". (See AFTER REPAIR
PROCEDURE [MZI-3.7].)



Are any DTC present?

Yes

Go to the applicable DTC inspection.
(See DTC TABLE [MZI-3.7].)

No

Troubleshooting completed.

DTC P0315

CKP system variation not learned

DETECTION

CONDITION



The PCM is unable to learn and correct for mechanical inaccuracies in the
crankshaft pulse wheel tooth spacing. This DTC disables the misfire

2008 Mazda CX-9 Grand Touring

2008 ENGINE PERFORMANCE On-Board Diagnostic (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:08:36 AM

Page 160

© 2005 Mitchell Repair Information Company, LLC.