Mazda CX 7. Manual — part 86

SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–41

01-03

End Of Sie

NO.11 ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE,
SURGES[L3 WITH TC]

id010339801700

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 Step 15.

No

Replace the delivery pipe.

14

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 the Step 18.

No

Go to the next step.

15

Connect the fuel pressure gauge between the
fuel pump and the high pressure fuel pump.
Measure the fuel pressure line of the low
pressure side.
(See01-14-5 FUEL LINE PRESSURE
INSPECTION[L3 WITH TC].)
Is the fuel pressure within the specification?

Yes

Go to the next step.

No

Inspect for the following:

• Fuel line restriction

• Fuel filter clogging

If normal replace the fuel pump.

16

Inspect the fuel injector for each cylinder.
(See01-14-27 FUEL INJECTOR
INSPECTION[L3 WITH TC].)
Are fuel injectors normal?

Yes

Go to the next step.

No

Replace the suspected fuel injector.
(See01-14-23 FUEL INJECTOR REMOVAL/
INSTALLATION[L3 WITH TC].)

17

Measure the compression pressure for each
cylinder.
(See01-10-9 COMPRESSION INSPECTION[L3
WITH TC].)
Are compression pressures within the
specification?

Yes

Replace the injector driver module.
If the problem remains, overhaul the engine.

No

Inspect for the following:

• Damaged valve seat

• Worn valve stem and valve guide

• Worn or stuck piston ring

• Worn piston, piston ring or cylinder

• Improper valve timing

Service if necessary.

18

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

11

ENGINE STALLS/QUITS (ACCELERATION/CRUISE)
ENGINE RUNS ROUGH (ACCELERATION/CRUISE)
BUCK/JERK (ACCELERATION/CRUISE/DECELERATION)
HESITATION/STUMBLE (ACCELERATION)
SURGES (ACCELERATION/CRUISE)

DESCRIPTION

• Engine stops unexpectedly at beginning of acceleration or during cruise.

• Engine stops unexpectedly while cruising.

• Engine speed fluctuates during acceleration or cruising.

• Engine misses during acceleration or cruising.

• Vehicle bucks/jerks during acceleration, during or deceleration.

• Momentary pause at beginning of acceleration or during acceleration

• Momentary minor irregularity in engine output

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–42

POSSIBLE CAUSE

• A/C system improper operation

• Air leakage from intake-air system

• Intake-air system restriction

• Purge solenoid valve malfunction

• Improper operation of electronic throttle control system

• EGR system malfunction

• Low engine compression

• Turbocharger malfunction

• Improper operation of wastegate control system

• Vacuum leakage

• Poor fuel quality

• Main relay intermittent malfunction

• Throttle body malfunction

• Engine overheating

• Spark plug malfunction

• Variable swirl system malfunction

• Air cleaner restriction

• PCV valve malfunction

• Improper valve timing due to jumping out timing chain

• Exhaust system and/or three-way catalytic converter restriction

• Intermittent open or short circuit in fuel pump circuit

• Incorrect fuel injection timing

• Inadequate fuel pressure (high or low pressure side)

• Fuel pressure sensor or related circuit malfunction

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

• Relief valve malfunction (built-in delivery pipe)

• High pressure fuel pump malfunction

• Fuel injector malfunction

• Improper fuel pump speed control operation

• Fuel pump mechanical malfunction

• Fuel line restriction or clogging

• Improper air/fuel mixture ratio control operation

• Erratic or no signal from CMP sensor

• Erratic signal from CKP sensor

• Front and/or rear HO2S sensor or related circuit malfunction

• Accelerator position sensor or related circuit malfunction

• MAF sensor or related circuit malfunction

• Neutral switch or related circuit malfunction

• ECT sensor or related circuit malfunction

• Manifold absolute pressure (MAP) sensor or related circuit malfunction

• IAT sensor No.1 or related circuit malfunction

• IAT sensor No.2 or related circuit malfunction

• Intermittent open or short circuit MAF sensor, accelerator position sensor, TP sensor and VSS

• ATX malfunction

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

• 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 injury or

death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete
“BEFORE REPAIR ROCEDURE” 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.

11

ENGINE STALLS/QUITS (ACCELERATION/CRUISE)
ENGINE RUNS ROUGH (ACCELERATION/CRUISE)
BUCK/JERK (ACCELERATION/CRUISE/DECELERATION)
HESITATION/STUMBLE (ACCELERATION)
SURGES (ACCELERATION/CRUISE)

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–43

01-03

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1

Inspect for the following:

• Fuel quality (proper octane, contamination,

winter/summer blend)

• Air leakage from intake-air system

• Intake-air system restriction

• Air cleaner element

• Clutch slippage

• Fuel leakage from fuel line

• Vacuum leakage

Are all items normal?

Yes

Go to the next step.

No

Service if necessary.
Repeat Step 1.

2

Perform the self-test function using the M-MDS.
Turn the ignition switch to the ON position.
Retrieve any DTCs.
Is a DTC displayed?

Yes

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

No

No DTC is displayed:
Go to the next step.

3

Access the ECT PID.
Verify that the ECT PID isless than 116

°C

{241

°F} during driving.

Is the ECT PID less than specified?

Yes

Go to the next step.

No

The cause of this concern could be from the cooling
system overheating.
Perform the symptom troubleshooting “NO.17
COOLING SYSTEM CONCERNS - OVERHEATING.”
(See01-03-60 NO.17 COOLING SYSTEM
CONCERNS-OVERHEATING[L3 WITH TC].)

4

Perform the Main Relay Operation Inspection
with wiggle the related harness.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the main relay operate properly?

Yes

Go to the next step.

No

Repair or replace for the intermittent fault.

5

Inspect CMP and CKP sensor for the following;

• Installation condition

(See01-40-45 CAMSHAFT POSITION
(CMP) SENSOR REMOVAL/
INSTALLATION[L3 WITH TC].)
(See01-40-42 CRANKSHAFT POSITION
(CKP) SENSOR REMOVAL/
INSTALLATION[L3 WITH TC].)

• Damaged trigger wheel and camshaft

• Open or short circuit in the wiring harnesses

Is there any malfunction detected?

Yes

Repair or replace the malfunctioning part according to
the inspection results.

No

Go to the next step.

6

Connect the M-MDS to DLC-2.
Access and monitor following PIDs using the
data monitor function while wiggle the harness
and under trouble condition.

• APP

• ECT

• MAF

• IAT

• IAT2

• MAP

• FP

• VSS

• O2S11

• O2S12

• LONGFT1

• SHTFT1

Do the PIDs indicate correct values?
(See01-40-6 PCM INSPECTION[L3 WITH TC].)

Yes

Go to the Step 13.

No

Inspect and repair or replace suspected parts and
related harnesses.
If the malfunction remains, perform the intermittent
concern troubleshooting.
(See01-03-76 INTERMITTENT CONCERN
TROUBLESHOOTING[L3 WITH TC].)
If the MAP PID remains without specified, go to the
next step.

7

Perform the EGR system operation inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does EGR system operate properly?

Yes

Go to the next step.

No

Inspect or replace the malfunctioning parts, according
to the inspection results.

8

Perform the A/C Cut-off Operation Inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the A/C Cut-off Operation work properly?

Yes

Go to the next step.

No

Repair or replace malfunctioning parts, according to
inspection results.

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SYMPTOM TROUBLESHOOTING [L3 WITH TC]

01-03–44

9

Perform the TP sweep inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the electronic throttle control system work
properly?

Yes

Visually inspect the throttle body (damaged/
scratching.) If normal, go to the next step.

No

Inspect or replace the malfunctioning parts, according
to the inspection results.

10

Perform the Variable Swirl Control System
Operation Inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the variable swirl system work properly?

Yes

Go to the next step.

No

Inspect or replace the malfunctioning parts, according
to the inspection results.

11

Perform the Purge Control System Operation
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

Inspect or replace the malfunctioning parts, according
to the inspection results.

12

Perform the Fuel Pump Speed Control
Inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the fuel pump speed control work
properly?

Yes

Go to the next step.

No

Inspect or replace the malfunctioning parts, according
to the inspection results.

13

Perform the Wastegate Control System
Operation Inspection.
(See01-03-78 ENGINE CONTROL SYSTEM
OPERATION INSPECTION[L3 WITH TC].)
Does the wastegate control system work
properly?

Yes

Go to the next step.

No

Inspect or replace the malfunctioning parts, according
to the inspection results.

14

Remove the parts necessary to inspect
turbocharger without removing the turbocharger.
Inspect if turbocharger compressor wheel is
bent, damaged, or interfering with housing on
vehicle.
(See01-13-17 TURBOCHARGER
INSPECTION[L3 WITH TC].)
Is there any problem?

Yes

Replace the turbocharger.

No

Go to the next step.

15

Inspect the turbocharger compressor wheel
locknut is loose or has fallen down inside
turbocharger.
Is there any problem?

Yes

Replace the turbocharger.

No

Go to the next step.

16

Inspect turbocharger compressor wheel by
hand.
Does the wheel turn easily and smoothly?

Yes

Go to the next step.

No

Replace the turbocharger.

17

Inspect the turbocharger turbine wheel is
damaged, cracked or interfering with housing on
vehicle.

Note

• Inspect all fins on each turbine wheel.

Is there any problem?

Yes

Replace the turbocharger.

No

Go to the next step.

18

Is any engine oil found inside turbocharger
turbine housing?

Yes

Excessive amount of oil is found:
Replace the turbocharger.
Small amount of oil is found:
Wipe oil out of vehicle, then go to the next step.

No

Go to the next step.

19

Is any engine oil found inside turbocharger
compressor housing?

Yes

Wipe oil out vehicle and install all removed parts in
Step 14. Then, go to the next step.

No

Turbocharger is normal.
Install all parts removed in Step 14.
Then, go to the next step.

20

Inspect for restriction in the exhaust system and
three-way catalytic converter (TWC).
Is there any restriction?

Yes

Replace the malfunctioning part.

No

Go to the next step.

21

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

Yes

Go to the next step.

No

Replace the PCV valve.

STEP

INSPECTION

RESULTS

ACTION

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