Mazda CX 7. Manual — part 66

ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–219

01-02

6

VERIFY CURRENT INPUT SIGNAL STATUS
UNDER TROUBLE CONDITION

• Inspect the same PIDs as Step 5 while

simulating FREEZE FRAME DATA condition.

• Is there any signal which causes drastic

changes?

Yes

Inspect the sensor and related wiring harnesses repair or
replace it.
Then go to Step 20.

No

Go to the next step.

7

VERIFY CURRENT INPUT SIGNAL STATUS OF
FRONT HO2S

• Access the O2S11 for P2177 PID using the M-

MDS.

• Check the PID under following accelerator

pedal condition in NEUTRAL.

• Is the PID reading normal?

— –0.1— 0.1 A when idle

— More than 0.25 mA just after release of

accelerator pedal (lean condition).

Yes

Go to the next step.

No

Visually inspect for any gas leakage between the exhaust
manifold and the front HO2S.
Then go to Step 20.

8

VERIFY CURRENT INPUT SIGNAL STATUS OF
MAF SENSOR

• Connect the M-MDS to the DLC-2.

• Start the engine.

• Access the MAF PID.

• Verify that the MAF PID changes quickly

according to engine speed.

• Is the PID normal?

Yes

Go to the next step.

No

Replace the MAF/IAT sensor, then go to Step 20.

9

INSPECT FOR EXCESSIVE AIR SUCTION OF
INTAKE AIR SYSTEM

• Visually inspect for loosen, cracks or damages

hoses on intake-air system.

• Is there any malfunction?

Yes

Repair or replace the source of air suction, then go to Step
20.

No

Go to the next step.

10

INSPECT PURGE SOLENOID OPERATION

• Perform the Purge Control System Inspection.

(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the purge control system work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection result, then go to Step 20.

11

INSPECT FUEL PRESSURE (HIGH-SIDE)

• Access and monitor FUEL_PRES PID.

• Is the FUEL_PRES PID value within the

specified?
(See01-40-6 PCM INSPECTION[L3 WITH
TC].)

Yes

Go to Step 15.

No

Go to the next step.

12

IDENTIFY CAUSE BY FUEL PRESSURE
SENSOR OR HIGH PRESSURE FUEL PUMP

• Is the vehicle accelerate performance

normally?

Yes

Go to the next step.

No

Go to Step 14.

13

INSPECT FUEL PRESSURE SENSOR

• Inspect the fuel pressure sensor.

• Is fuel leakage found?

(See01-40-35 FUEL PRESSURE SENSOR
INSPECTION[L3 WITH TC].)

• Is the fuel pressure sensor normal?

Yes

Go to Step 15.

No

Replace the fuel delivery pipe, then go to Step 20.

14

INSPECT HIGH PRESSURE FUEL PUMP

• 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

Go to Step 20.

No

Go to the next step.

15

INSPECT FUEL PRESSURE (LOW-SIDE)

• Connect the fuel pressure gauge between fuel

pump and high pressure fuel pump.

• Measure the low side fuel pressure.

(See01-14-5 FUEL LINE PRESSURE
INSPECTION[L3 WITH TC].)

• Is the low side fuel pressure within the

specified?

Yes

Go to the next step.

No

Inspect for following:

• Fuel line restriction

• Fuel filter clogging

If okay replace the fuel pump. Then go to Step 20.

STEP

INSPECTION

ACTION

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–220

End Of Sie

DTC P2178[L3 WITH TC]

id010239812400

16

INSPECT IGNITION SYSTEM

• Perform the spark test.

(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• 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, then go to Step 20.

17

INSPECT ENGINE COMPRESSION

• Inspect the engine compression.

(See01-10-9 COMPRESSION
INSPECTION[L3 WITH TC].)

• Is it normal?

Yes

Go to the next step.

No

Implement the engine overhaul for repairs, then go to Step
20.

18

INSPECT VARIABLE VALVE TIMING CONTROL
SYSTEM OPERATION

• Inspect the variable valve timing control system

operation.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the variable valve timing control system

work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection results, then go to Step 20.

19

INSPECT FUEL INJECTOR OPERATION

• Remove the fuel injector.

• Inspect the fuel injector (resistance, injection

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

• Is the fuel injector normal?

Yes

Go to the next step.

No

Replace the fuel injector, then go to the next step.

20

VERIFY TROUBLESHOOTING OF DTC P2177
COMPLETED

• Make sure to reconnect all disconnected

connectors.

• Clear the DTC from the PCM memory using

the M-MDS.

• Perform the PCM Adaptive Memory Produce

Drive Mode.
(See01-02-10 OBD-II DRIVE MODE[L3 WITH
TC].)

• Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.
(See01-40-6 PCM REMOVAL/INSTALLATION[L3 WITH
TC].)

No

Go to the next step.

21

VERIFY AFTER REPAIR PROCEDURE

• Perform the “AFTER REPAIR PROCEDURE”.

(See01-14-4 AFTER REPAIR
PROCEDURE[L3 WITH TC].)

• Are any DTCs present?

Yes

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

No

Troubleshooting completed.

STEP

INSPECTION

ACTION

DTC P2178

Fuel system too rich at off idle

DETECTION

CONDITION

• PCM monitors the short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) during closed loop fuel

control at off-idle. If the LONGFT and the sum total of these fuel trims exceed the preprogrammed criteria,
the PCM determines that fuel system is too rich at off-idle.

Diagnostic support note

• This is a continuous monitor. (Fuel system)

• MIL illuminates if the PCM detects the above malfunctioning condition in two consecutive drive cycles or in

one drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if the PCM detects the above malfunction conditions during the first drive

cycle.

• FREEZE FRAME DATA is available.

• DTCs are stored in the PCM memory.

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–221

01-02

Diagnostic procedure

POSSIBLE

CAUSE

• Misfire

• Front HO2S deterioration

• Front HO2S heater malfunction

• MAF sensor malfunction

• Pressure regulator malfunction

• Fuel pressure sensor malfunction

• Relief valve (built-in fuel delivery pipe) malfunction

• Spill valve control solenoid valve (built-in high pressure fuel pump) malfunction

• High pressure fuel pump malfunction

• Fuel pump malfunction

• EGR valve improper operation

• Variable swirl control improper operation

• Purge solenoid valve improper operation

• Purge solenoid valve malfunction (stuck open)

• Purge solenoid hoses improper connection

• PCV valve malfunction

• Variable valve timing control system improper operation

• PCM malfunction

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA AND
DIAGNOSTIC MONITORING TEST RESULTS
HAVE BEEN RECORDED

• Have the FREEZE FRAME DATA and

DIAGNOSTIC MONITORING TEST RESULTS
(Fuel system related) been recorded?

Yes

Go to the next step.

No

Record the FREEZE FRAME DATA and DIAGNOSTIC
MONITORING TEST RESULTS 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 repair information available?

Yes

Perform the repair or diagnosis according to the available
repair information.

• 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 to off, then to the ON

position (Engine off).

• Verify related pending code or stored DTCs.

• Are other DTCs present?

Yes

If misfire the DTC is present, go to Step 8.
If other DTCs is present, go to the applicable DTC
inspection.
(See01-02-13 DTC TABLE[L3 WITH TC].)

No

If driveability concern is present, go to Step 8.
If not, go to the next step.

4

IDENTIFY TRIGGER DTC FOR FREEZE FRAME
DATA

• Is DTC P2178 on FREEZE FRAME DATA?

Yes

Go to the next step.

No

Go to troubleshooting procedures for DTC on FREEZE
FRAME DATA.

5

VERIFY CURRENT INPUT SIGNAL STATUS
(IGNITION SWITCH TO THE ON POSITION/
IDLE)

• Access the APP1, APP2, ECT, MAF, TP and

VSS PIDs using the M-MDS.

• Is there any signal that is far out of specification

when the ignition switch is at the ON position
and the engine runs?

Yes

Inspect the sensor and excessive resistance in related
wiring harnesses.
Repair if necessary.
Then go to Step 19.

No

Go to the next step.

6

VERIFY CURRENT INPUT SIGNAL STATUS
UNDER TROUBLE CONDITION

• Inspect the same PIDs as Step 5 while

simulating FREEZE FRAME DATA condition.

• Is there any signal which causes drastic

changes?

Yes

Inspect the sensor and related wiring harnesses, repair or
replace it.
Then go to Step 19.

No

Go to the next step.

7

VERIFY CURRENT INPUT SIGNAL STATUS OF
FRONT HO2S

• Access the O2S11 for P2177 PID using the M-

MDS.

• Check the PID under following accelerator

pedal condition in NEUTRAL.

• Is the PID reading normal?

— –0.1— 0.1 A when idle

— More than 0.25 mA just after release of

accelerator pedal (lean condition)

Yes

Go to the next step.

No

Visually inspect for any gas leakage between the exhaust
manifold and the front HO2S.
Then go to Step 19.

DTC P2178

Fuel system too rich at off idle

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ON-BOARD DIAGNOSTIC [L3 WITH TC]

01-02–222

8

VERIFY CURRENT INPUT SIGNAL STATUS OF
MAF SENSOR

• Connect the M-MDS to the DLC-2

• Start the engine.

• Access the MAF PID.

• Verify that the MAF PID changes quickly

according to engine speed.

• Is the PID normal?

Yes

Go to the next step.

No

Replace the MAF/IAT sensor, then go to Step 19.

9

INSPECT PURGE SOLENOID OPERATION

• Perform the Purge Control System Inspection.

(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the purge control system work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection result, then go to Step 19.

10

INSPECT PCV VALVE OPERATION

• Inspect the PCV valve operation.

(See01-16-14 POSITIVE CRANKCASE
VENTILATION (PCV) VALVE INSPECTION[L3
WITH TC].)

• Is the PCV valve normal?

Yes

Go to the next step.

No

Replace the PCV valve, then go to Step 19

11

INSPECT EGR VALVE OPERATION

• Perform the EGR Control System Inspection.

(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the EGR control system work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection result, then go to Step 19.

12

INSPECT VARIABLE SWIRL CONTROL
OPERATION

• Perform the Variable Swirl Control Operation

Inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the variable swirl control work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection result, then go to Step 19.

13

INSPECT VARIABLE VALVE TIMING CONTROL
SYSTEM OPERATION

• Inspect the variable valve timing control system

operation.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)

• Does the variable valve timing control system

work properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to
inspection results, then go to Step 19.

14

INSPECT FUEL PRESSURE (HIGH-SIDE)

• Access and monitor FUEL_PRES PID.

• Is the FUEL_PRES PID value within the

specified?
(See01-40-6 PCM INSPECTION[L3 WITH
TC].)

Yes

Go to Step 18.

No

Go to the next step.

15

IDENTIFY CAUSE BY FUEL PRESSURE
SENSOR OR HIGH PRESSURE FUEL PUMP

• Is the vehicle accelerate performance

normally?

Yes

Go to the next step.

No

Go to Step 17.

16

INSPECT FUEL PRESSURE SENSOR

• 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.

No

Replace the fuel delivery pipe, then go to Step 19.

17

INSPECT HIGH PRESSURE FUEL PUMP

• 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

Go to Step 19.

No

Go to the next step.

STEP

INSPECTION

ACTION

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