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Mazda CX 7. Manual - part 94

SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–73

01-03

End Of Sie

NO.29 SPARK PLUG CONDITION[L3 WITH TC]

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Diagnostic procedure

Verify test results.

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

• If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform the

repair or diagnosis.

— If the vehicle is repaired, troubleshooting is completed.

— If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later

calibration is available. Retest.

STEP

INSPECTION

ACTION

SPARK PLUG CONDITION

DESCRIPTION

Incorrect spark plug condition

POSSIBLE CAUSE

Note

• Inspecting the condition of the spark plugs can determine whether a problem is related to a

specific cylinder or possibly all cylinders.

Wet/carbon stuck on specific plug:

• Spark— Weak, not visible

• Air/fuel mixture— Excessive fuel injection volume

• Compression— No compression, low compression

• Malfunctioning spark plug

Grayish white with specific plug:

• Air/fuel mixture— Insufficient fuel injection volume

• Malfunctioning spark plug

Wet/carbon is stuck on all plugs:

• Spark— Spark weak

• Air/fuel mixture— Too rich

• Compression— Low compression

• Clogging in intake/exhaust system

Grayish white with all plugs:

• Air/fuel mixture— Too lean

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 REPAIR PROCEDURE” and “AFTER REPAIR PROCEDURE” described in this
manual.
(See01-14-4 BEFORE REPAIR PROCEDURE[L3 WITH TC].)
(See01-14-4 AFTER REPAIR PROCEDURE[L3 WITH TC].)

Caution

• Disconnecting/connecting the quick release connector without cleaning it may possibly

cause damage to the fuel pipe and quick release connector. Always clean the quick release
connector joint area before disconnecting/connecting, and make sure that it is free of
foreign material.

STEP

INSPECTION

RESULTS

ACTION

Remove all the spark plugs.
Inspect the spark plug condition.
Is the spark plug condition normal?

Yes

Troubleshooting completed.

Specific plug is wet or covered with carbon:
Go to the next step.
Specific plug looks grayish white:
Go to Step 9.
All plugs are wet or covered with carbon:
Go to Step 11.
All plugs look grayish white:
Go to Step 19.

Is the spark plug wet/covered with carbon from
engine oil?

Yes

Inspect all areas related to oil.

Go to the next step.

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–74

Inspect the spark plugs for the following:

• Cracked insulator

• Heat range

• Air gap

• Worn electrode

Is the spark plug normal?

Yes

Go to the next step.

Replace the spark plug.

Inspect the compression pressure at the
suspected malfunctioning cylinder.
Is the compression pressure correct?
(See01-10-9 COMPRESSION INSPECTION[L3
WITH TC].)

Yes

Go to the next step.

Repair or replace the malfunctioning parts.

Install all the spark plugs.
Perform the spark test at the suspected
malfunctioning cylinder.
Is a strong blue spark visible?
(Compare with normal cylinder.)

Yes

Go to the next step.

Repair or replace the malfunctioning parts.

Access and monitor the FUEL_PRES PID.
Is the FUEL_PRES PID value within the
specification?
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Yes

Inspect the suspected cylinders fuel injector for the
following:

• Open or short circuit in the fuel injector

(See01-14-27 FUEL INJECTOR INSPECTION[L3
WITH TC].)

Go to the next step.

Inspect the fuel pressure sensor.
(See01-40-35 FUEL PRESSURE SENSOR
INSPECTION[L3 WITH TC].)
Is the fuel pressure sensor normal?

Yes

Go to the next step.

Replace the delivery pipe.

Inspect the high pressure fuel pump.
(See01-14-19 HIGH PRESSURE FUEL PUMP
INSPECTION[L3 WITH TC].)
Is the high pressure fuel pump normal?

Yes

Replace the delivery pipe.
Retest Step 6
If the FUEL_PRES PID indication is other that the
specification, replace the high pressure fuel pump.

Replace the high pressure fuel pump.

Inspect the spark plug for the following.

• Heat range

• Air gap

Is the spark plug normal?

Yes

Go to the next step.

Replace the spark plug.

Perform the KOER self-test function using the M-
MDS.
(See01-02-10 KOEO/KOER SELF TEST[L3
WITH TC].)
Is the suspected cylinder injector circuit related
DTC (P0201, P0202, P0203 or P0204) present?

Yes

Go to appropriate the DTC test.
(See01-02-13 DTC TABLE[L3 WITH TC].)

Inspect the suspect cylinder fuel injector for the
following:

• Resistance

(See01-14-27 FUEL INJECTOR INSPECTION[L3
WITH TC].)

Is the air cleaner element free of blockage?

Yes

Go to the next step.

Replace the air cleaner element.

Perform the spark test.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Is a strong blue spark visible at each cylinder?

Yes

Go to the next step.

Repair or replace the malfunctioning parts.

Access and monitor the FUEL_PRES PID.
Is the FUEL_PRES PID value within the
specification?
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Yes

Go to step 16.

Go to the next step.

Inspect the fuel pressure sensor.
(See01-40-35 FUEL PRESSURE SENSOR
INSPECTION[L3 WITH TC].)
Is the fuel pressure sensor normal?

Yes

Go to the next step.

Replace the delivery pipe.

Inspect the high pressure fuel pump.
(See01-14-19 HIGH PRESSURE FUEL PUMP
INSPECTION[L3 WITH TC].)
Is the high pressure fuel pump normal?

Yes

Replace the delivery pipe.
Retest Step 13.
If the FUEL_PRES PID indication is other that the
specification, replace the high pressure fuel pump.

Replace the high pressure fuel pump.

STEP

INSPECTION

RESULTS

ACTION

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–75

01-03

End Of Sie

Inspect the following PIDs:

• ECT

• O2S11 (When engine can be started)

• MAF

(See01-40-6 PCM INSPECTION[L3 WITH TC].)
Are the PIDs normal?

Yes

Go to the next step.

Repair or replace the malfunctioning parts.

Perform the purge control inspection.
(When engine can be started)
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Is the purge control correct?

Yes

Go to the next step.

Repair or replace the malfunctioning parts.

Perform the compression inspection.
Is the compression correct?

Yes

Inspect for clogging in the exhaust system.

Repair or replace the malfunctioning parts.

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

Yes

Repair or replace the malfunctioning part.

Go to the next step.

Access and monitor the FUEL_PRES PID.
Is the FUEL_PRES PID value within the
specification?
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Yes

Inspect for the following PIDs:

• ECT

• O2S11

• O2S12

• MAF

(See01-40-6 PCM INSPECTION[L3 WITH TC].)
Inspect the PCM ground condition.

Go to the next step.

Is vehicle accelerate performance normally?

Yes

Go to the next step.

Go to Step 13.

Inspect the fuel pressure sensor.
(See01-40-35 FUEL PRESSURE SENSOR
INSPECTION[L3 WITH TC].)
Is the fuel pressure sensor normal?

Yes

Go to the next step.

Replace the delivery pipe.

Replace the high pressure fuel pump.
Monitor FUEL_PRES PID.
Is the FUEL_PRES PID value within the
specified?
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Yes

Troubleshooting is completed.
Go to Step 16.

Inspect following PIDs.

• ECT

• O2S11

• O2S12

• MAF

(See01-40-6 PCM INSPECTION[L3 WITH TC].)
Inspect PCM ground condition.

Verify test results.

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

• If a malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform the

repair or diagnosis.
— If the vehicle is repaired, troubleshooting is completed.

— If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later

calibration is available. Retest.

STEP

INSPECTION

RESULTS

ACTION

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–76

INTERMITTENT CONCERN TROUBLESHOOTING[L3 WITH TC]

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Vibration Method

• If a malfunction occurs or becomes worse while driving on a rough road or when the engine is vibrating,

perform the steps below.

Note

• There are several reasons why the vehicle or engine vibration could cause an electrical malfunction.

Check the following:

— Connectors are not fully seated.

— Wiring harnesses do not have full play.

— Wires laying across brackets or moving parts.

— Wires routed too close to hot parts.

• An improperly routed, improperly clamped, or loose harness can cause a wiring harness to become

pinched between parts.

• The connector joints, points of vibration, and places where the wiring harnesses pass through the firewall

and body panels are the major areas to be checked.

Inspection Method for Switch Connectors or Wires

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

Note

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

3. Access the 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 the PID value is unstable, check for a poor

connection.

Inspection Method for Sensor Connectors or Wires

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 idling.

3. Access the PIDs for the switch you are inspecting.
4. Slightly shake each connector or wiring harness

vertically and horizontally while monitoring the
PID.

• If the PID value is unstable, check for poor

connection.

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