Mazda CX-9 Grand Touring. Manual — part 329

DIAGNOSTIC PROCEDURE

NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK (MZI-3.7)
DIAGNOSTIC PROCEDURE

POSSIBLE

CAUSE



Spark plug malfunction



Air leakage from intake-air system



Erratic signal from CKP sensor



Erratic signal from CMP sensor



Improper air/fuel mixture ratio control



Air cleaner restriction



Improper operation of electronic throttle control system



PCV valve malfunction



Inadequate fuel pressure



Purge solenoid valve malfunction



MAF sensor contamination



Incorrect MAF sensor GND voltage



Restriction in exhaust system



Pressure regulator malfunction (built-in fuel pump unit)

WARNING:

The following troubleshooting flow chart contains the fuel system diagnosis
and repair procedures. Read the following warnings before servicing the fuel
system:



Fuel vapor is hazardous. It can easily ignite, causing serious injury
and damage. Always keep sparks and flames away from fuel.



Fuel line spills and leakage are dangerous. Fuel can ignite and cause
serious injuries or death and damage. Fuel can also irritate skin and
eyes. To prevent this, always complete "BEFORE SERVICE
PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this
manual.

(See BEFORE SERVICE PRECAUTION [MZI-3.7] .)

(See AFTER SERVICE PRECAUTION [MZI-3.7] .)

CAUTION:



Disconnecting/connecting quick release connector without cleaning it
may cause damage to fuel pipe and quick release connector. Always
clean quick release connector joint area before
disconnecting/connecting, and make sure that it is free of foreign
material.

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:04 AM

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© 2005 Mitchell Repair Information Company, LLC.

STEP

INSPECTION

RESULTS

ACTION

1

Inspect for the following:



Vacuum leakage



Proper fuel quality (such as proper
octane, contamination,
winter/summer blend)



Loose bands on intake-air system



Cracks on intake-air system parts



Intake-air system restriction (such
as air cleaner element, fresh air
duct.)

Are all items normal?

Yes

Go to the next step.

No

Service if necessary.

Repeat Step 1.

2

Connect the M-MDS to the DLC-2.
Turn the ignition switch to the ON
position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?

Yes

DTC is displayed:
Go to the appropriate DTC inspection.
(See DTC TABLE [MZI-3.7] .)

No

No DTC is displayed:

Go to the next step.

3

Is engine overheating?

Yes

Go to symptom troubleshooting "No. 17
Cooling system concerns-Overheating".
(See NO.17 COOLING SYSTEM
CONCERNS-OVERHEATING [MZI-
3.7].)

No

Go to the next step.

4

Inspect the ignition coil related wiring
harness condition (intermittent open or
short circuit) for all cylinders.
Are wiring harness conditions normal?

Yes

Go to the next step.

No

Repair the wiring harnesses.

5

Inspect the spark plug conditions.
Is spark plug wet, covered with carbon or
grayish white?

Yes

Spark plug is wet or covered with carbon:

Inspect for fuel leakage from fuel injector.
Spark plug is grayish white:
Inspect the fuel injector for clogging.

No

Install the spark plugs on original cylinders.

Go to the next step.

6

Visually inspect the CKP sensor and
teeth of crankshaft pulley.
Are the CKP sensor and teeth of
crankshaft pulley normal?

Yes

Go to the next step.

No

Replace the malfunctioning part.

7

Remove and shake the PCV valve.
Does the PCV valve rattle?

Yes

Go to the next step.

No

Replace the PCV valve.

Inspect the electronic throttle control system

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:04 AM

Page 23

© 2005 Mitchell Repair Information Company, LLC.

8

Attempt to start engine at part throttle.
Does engine run smoothly at part
throttle?

Yes

operation.
(See ENGINE CONTROL SYSTEM
OPERATION INSPECTION [MZI-3.7].)

No

Go to the next step.

9

Install the fuel pressure gauge between
the fuel pipe and fuel distributor.
Short check connector terminal F/P to
body GND using a jumper wiring.
Turn the ignition switch to the ON
position.
Is fuel line pressure correct with ignition
switch ON?
(See FUEL LINE PRESSURE
INSPECTION [MZI-3.7] .)

Yes

Go to the next step.

No

Zero or low:

Inspect the fuel pump relay and the fuel

pump circuit.

Inspect the fuel line for clogging.

If there is no malfunction, replace the fuel

pump unit.

(See FUEL PUMP UNIT

REMOVAL/INSTALLATION [MZI-

3.7] .)
High:

Replace the fuel pump unit.

(See FUEL PUMP UNIT

REMOVAL/INSTALLATION [MZI-

3.7] .)

10

Is the fuel line pressure held after ignition
switch is turned off?
(See FUEL LINE PRESSURE
INSPECTION [MZI-3.7] .)

Yes

Go to the next step.

No

Inspect the fuel injector.

(See FUEL INJECTOR INSPECTION

[MZI-3.7] .)

If the fuel injector is normal, replace the fuel

pump unit.

(See FUEL PUMP UNIT

REMOVAL/INSTALLATION [MZI-

3.7] .)

11

Disconnect a vacuum hose from purge
solenoid valve and plug opening end of
vacuum hose.
Start engine.
Is starting condition improved?

Yes

Inspect if the purge solenoid valve is stuck
open.

No

Go to the next step.

12

Inspect the MAF sensor for following:



Contamination



MAF sensor terminal B voltage
(GND circuit)

Is there any contamination?

Yes

Repair or replace the malfunctioning part.

No

Go to the next step.

13

Visually inspect the exhaust system part.
Is there any deformed exhaust system
part?

Yes

Replace the suspected part.

No

Go to the next step.

Inspect the starting system.

Yes

Inspect for loose connectors or poor

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:04 AM

Page 24

© 2005 Mitchell Repair Information Company, LLC.

NO.5 ENGINE STALLS-AFTER START/AT IDLE [MZI-3.7]

NO.5 ENGINE STALLS-AFTER START/AT IDLE (MZI-3.7) DETECTION CONDITIONS AND
POSSIBLE CAUSES

14

(See STARTER INSPECTION [MZI-
3.7] .)
Is starting system normal?

terminal contact.

No

Repair or replace components as required.

15



Verify test results.



If normal, return to diagnostic index to service any additional symptoms.

(See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].)



If malfunction remains, inspect related Service Bulletins and/or On-line Repair
Information and perform repair or diagnosis.



If vehicle is repaired, troubleshooting completed.



If vehicle is not repaired or additional diagnostic information is not available,
Replace the PCM.

(See PCM REMOVAL/INSTALLATION [MZI-3.7] .)

5

ENGINE STALLS-AFTER START/AT IDLE

DESCRIPTION



Engine stops unexpectedly.



A/C system operation is improper



Air leakage from intake-air system parts



Purge solenoid valve malfunction



Improper operation of electronic throttle control system



No signal from CKP sensor due to sensor, related wire or wrong installation



Vacuum leakage



Engine overheating



Low engine compression



Erratic signal to ignition coil



Poor fuel quality



PCV valve malfunction



Air cleaner restriction



Restriction in exhaust system



Electrical connector disconnection



Open or short circuit in fuel pump body and related wiring harness



No battery power supply to PCM or poor GND



Inadequate fuel pressure



Fuel pump body mechanical malfunction

2008 Mazda CX-9 Grand Touring

2008 ENGINE Symptom Troubleshooting (MZI-3.7) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:10:05 AM

Page 25

© 2005 Mitchell Repair Information Company, LLC.