Mazda CX-9 Grand Touring. Manual - part 339

 

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Mazda CX-9 Grand Touring. Manual - part 339

 

 

DIAGNOSTIC PROCEDURE 

NO.13 KNOCKING/PINGING-ACCELERATION/CRUISE (MZI-3.7) DIAGNOSTIC PROCEDURE 

material.  

STEP

INSPECTION

RESULTS

ACTION

1

Connect the M-MDS to the DLC-2. 
Access ECT PID. 
Verify ECT PID is less than 116°C 
{241°F}
 during driving. 
Is ECT PID less than specification?

Yes

Go to the next step.

No

Inspect the cooling system for cause of 

overheating.

2

Connect the M-MDS to the DLC-2. 
Access IAT and MAF PIDs. 
Monitor each PID. 
(See PCM INSPECTION [MZI-
3.7]
 .) 
Are PIDs normal?

Yes

Go to the next step.

No

IAT PID:  

Inspect IAT sensor 

MAF PID:  

Inspect MAF sensor

3

Connect the M-MDS to the DLC-2. 
Turn the ignition switch to the ON 
position (engine off). 
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.

4

Is engine compression correct?

Yes

Go to the next step.

No

Inspect for cause.

5

Install fuel pressure gauge between 
fuel pipe and fuel distributor. 
Start the engine and idle it. 
Measure fuel line pressure during 
idle. 
Is fuel line pressure correct during 
idle? 
(See FUEL LINE PRESSURE 
INSPECTION [MZI-3.7]
 .)

Yes

Inspect the ignition timing.

No

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] .)

6

Inspect the knock sensor. 
Is the knock sensor normal?

Yes

Inspect ignition timing.

No

Replace the knock sensor.

7

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 

 

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 62 

© 2005 Mitchell Repair Information Company, LLC. 

NO.14 POOR FUEL ECONOMY [MZI-3.7] 

NO.14 POOR FUEL ECONOMY (MZI-3.7) DETECTION CONDITIONS AND POSSIBLE CAUSES 

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] .) 

14

POOR FUEL ECONOMY

DESCRIPTION Fuel economy is unsatisfactory.

POSSIBLE 

CAUSE 

Contaminated air cleaner element  

Engine cooling system malfunction  

Improper ATF level  

Weak spark  

Poor fuel quality  

Erratic or no signal from CMP sensor  

Improper variable valve timing control system operation  

Improper coolant level  

Inadequate fuel pressure  

Spark plug malfunction  

PCV valve malfunction  

Brake dragging  

Improper valve timing due to jumping out of timing chain  

Contaminated MAF sensor  

Improper engine compression  

Exhaust system clogging 

WARNING:

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

 

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 63 

© 2005 Mitchell Repair Information Company, LLC. 

DIAGNOSTIC PROCEDURE 

NO.14 POOR FUEL ECONOMY (MZI-3.7) DIAGNOSTIC PROCEDURE 

(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.  

STEP

INSPECTION

RESULTS

ACTION

1

Inspect for the following: 

Air cleaner element for 
contamination  

ATF level  

Fuel quality  

Coolant level  

Brake dragging  

 
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

Access ECT PID. 
Drive vehicle while monitoring PID.
(See PCM INSPECTION [MZI-
3.7]
 .) 
Is PID within specification?

Yes

Go to the next step.

No

Inspect for coolant leakage, cooling fan and 

condenser fan operations or thermostat 

operation.

4

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 

according to spark test result.

Install the fuel pressure gauge 

Yes

Go to the next step.

Low:  

 

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 64 

© 2005 Mitchell Repair Information Company, LLC. 

5

between the fuel pipe and the fuel 
distributor. 
Start the engine and idle it. 
Measure fuel line pressure during 
idle. 
Is fuel line pressure correct during 
idle? 
(See FUEL LINE PRESSURE 
INSPECTION [MZI-3.7]
 .)

No

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] .)

6

Inspect for variable valve timing 
control system operation. 
(See ENGINE CONTROL 
SYSTEM OPERATION 
INSPECTION [MZI-3.7]
.) 
Does the variable valve timing 
control system function properly?

Yes

Go to the next step.

No

Repair or 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.

8

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

Yes

Replace the suspected part.

No

Go to the next step.

9

Inspect for contaminated MAF 
sensor. 
Is there any contamination?

Yes

Go to the next step.

No

Inspect for cause.

10

Inspect the MAF sensor for 
contamination. 
Is there any contamination?

Yes

Replace MAF sensor.

No

Go to the next step.

11

Is engine compression correct?

Yes

Inspect the valve timing.

No

Inspect for cause.

12

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] .) 

 

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 65 

© 2005 Mitchell Repair Information Company, LLC. 

 

 

 

 

 

 

 

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