Mazda CX-9 Grand Touring. Manual - part 347

INSPECTION [MZI-
3.7] .) 

 
Are all above items normal?



For No.4 cylinder: 2BH  



For No.5 cylinder: 2BB  



For No.6 cylinder: 2BD  

No

Replace the fuel injector.

9

Is the air cleaner element free of 
clogging?

Yes

Go to the next step.

No

Replace the air cleaner element.

10

Perform the spark test. 
(See ENGINE CONTROL 
SYSTEM OPERATION 
INSPECTION [MZI-3.7].) 
Is strong blue spark visible at each 
cylinder?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part.

11

Install the fuel pressure gauge 
between the fuel filter and fuel 
distributor. 
Short check connector terminal 
F/P to body GND using a jumper 
wiring. 
Turn the ignition switch to the ON 
position (Engine off). 
Is the fuel line pressure correct 
with ignition switch at 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 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] .)

12

Inspect the following PIDs: 



ECT  



O2S11 (When engine can be 
started.)  



O2S12 (When engine can be 
started.)  



O2S21 (When engine can be 
started.)  



O2S22 (When engine can be 
started.)  



MAF  

 
(See PCM INSPECTION [MZI-
3.7] .) 
Are PIDs normal?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part.

Perform the purge control 
inspection. 
(When engine can be started.) 

Yes

Go to the next step.

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:10:06 AM

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© 2005 Mitchell Repair Information Company, LLC. 

13

(See ENGINE CONTROL 
SYSTEM OPERATION 
INSPECTION [MZI-3.7].) 
Is the purge control correct?

No

Repair or replace the malfunctioning part.

14

Perform compression inspection. 
(See COMPRESSION 
INSPECTION [MZI-3.7] .) 
Is compression correct?

Yes

Visually inspect for deformed exhaust system part.

No

Repair or replace the malfunctioning part.

15

When the engine cannot be 
started, inspect the intake-air 
system for air leakage. 
When the engine can be started, 
perform intake manifold vacuum 
inspection. 
Is air sucked in from intake-air 
system?

Yes

Repair or replace the malfunctioning part.

No

Go to the next step.

16

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

Yes

Inspect the following PIDs: 



ECT  



O2S11  



O2S12  



O2S21  



O2S22  



MAF 

(See PCM INSPECTION [MZI-3.7] .) 

 
Inspect PCM GND condition.

No

Zero or low:  

Inspect the fuel pump relay and 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] .)



Verify test results. 



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

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

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:10:06 AM

Page 95 

© 2005 Mitchell Repair Information Company, LLC. 

INTERMITTENT CONCERN TROUBLESHOOTING [MZI-3.7] 

VIBRATION METHOD 



If malfunction occurs or becomes worse while driving on a rough road or when the engine is vibrating, 
perform the steps below. 

Inspection Method for Switch Connectors or Wiring Harnesses 

1. Connect the M-MDS to the DLC-2.  

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

3. Access PIDs for the switch you are inspecting.  

4. Turn the switch on manually.  

5. Slightly shake each connector or wiring harness vertically and horizontally while monitoring the PID. 



If PID value is unstable, inspect for poor connection. 

17



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] .) 

NOTE:



There are several reasons vehicle or engine vibration could cause an 
electrical malfunction. Inspect the following: 



Connectors not fully seated  



Wiring harnesses not having full play  



Wiring harnesses laying across brackets or moving parts  



Wiring harnesses routed too close to hot parts  



An improperly routed, improperly clamped, or loose wiring harness 
can cause wiring to become pinched between parts.  



The connector joints, points of vibration, and places where wiring 
harnesses pass such as through the firewall and body panels are the 
major areas to be checked.  

NOTE:



If the engine starts and runs, perform the following steps during idle. 

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:10:06 AM

Page 96 

© 2005 Mitchell Repair Information Company, LLC. 

Fig. 9: Inspection Method For Wiring Harnesses 
Courtesy of MAZDA MOTORS CORP. 

Inspection Method for Sensor Connectors or Wiring Harnesses 

1. Connect the M-MDS to the DLC-2.  

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

3. Access PIDs for the switch you are inspecting.  

4. Slightly shake each connector or wiring harness vertically and horizontally while monitoring the PID. 



If PID value is unstable, inspect for poor connection. 

Fig. 10: Inspection Method For Sensor Connectors 
Courtesy of MAZDA MOTORS CORP. 

Inspection Method for Sensors 

1. Connect the M-MDS to the DLC-2.  

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

NOTE:



If the engine starts and runs, perform the following steps during idle. 

NOTE:



If the engine starts and runs, perform the following steps during idle. 

 

2008 Mazda CX-9 Grand Touring 

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

  

Microsoft 

 

Sunday, November 15, 2009 10:10:06 AM

Page 97 

© 2005 Mitchell Repair Information Company, LLC.