Mazda 6. Manual - part 171

F–206

TROUBLESHOOTING

End Of Sie

Install fuel pressure gauge between fuel pipe
and fuel distributor.
Connect jumper wire between F/P terminal at
DLC-2 in engine compartment and GND.
Turn ignition switch to ON position.
Is fuel line pressure correct with ignition switch
to ON position?
(See

F–20 FUEL LINE PRESSURE

INSPECTION

)

Yes

Go to next step.

Zero or low:
Inspect for clogged fuel line.
If okay, replace fuel pump unit.
High:
Replace fuel pump unit.

Visually inspect for fuel leakage at fuel injector
O-ring and fuel line.
Service as necessary.
Is fuel line pressure held after ignition switch is
turned off?
(See

F–20 FUEL LINE PRESSURE

INSPECTION

)

Yes

Go to next step.

Inspect fuel injector.
If fuel injector is okay, replace fuel pump unit.

Note

• Following test is for engine stalling with A/

C on. If other symptom exists, go to next
step.

Connect a pressure gauge to A/C low and high
pressure side lines.
Turn A/C on and measure low side and high side
pressure.
Are pressure within specifications?
(See

U–12 REFRIGERANT PRESSURE

CHECK

Yes

Go to next step.

If A/C is always on, go to symptom troubleshooting
"No.24 A/C is always on or A/C compressor runs
continuously".
For other symptoms, inspect following:

• Refrigerant charging amount

• Condenser fan operation

Note

• The following test should be performed for

symptom with cruise control ON. If other
symptoms exist, go to next step.

Inspect cruise control system.
Is cruise control system okay?

Yes

Go to next step.

Repair or replace malfunctioning parts.

Disconnect vacuum hose between purge
solenoid valve and intake manifold from purge
solenoid valve side.
Plug opening end of vacuum hose.
Drive vehicle.
Does engine condition improve?

Yes

Go to next step.
Inspect if purge solenoid valve sticks open
mechanically.
Inspect evaporative emission control system.

Go to next step.

Visually inspect CMP sensor and projections of
camshaft pulley.
Are CMP sensor and projections of camshaft
pulley okay?

Yes

Go to next step.

Replace malfunctioning parts.

Inspect VTCS operation.
(See

F–231 Variable Tumble Control System

(VTCS) Operation Inspection

Is VTCS okay?

Yes

Go to next step.

Replace or replace malfunctioning parts.

Inspect EGR system.
(See

F–233 EGR Control System Inspection

Is EGR system okay?

Yes

Go to next step.

Replace malfunctioning parts.

Is engine compression correct?

Yes

Inspect following:

• Valve timing

• Internal transaxle part (ATX)

• Clutch (MTX)

Inspect for cause.

Verify test results.

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

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

TROUBLESHOOTING

F–207

NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISE

A6E398018881W14

Diagnostic procedure

LACK/LOSS OF POWER — ACCELERATION/CRUISE

DESCRIPTION

Performance is poor under load (e.g., power down when climbing hills).

POSSIBLE CAUSE

• Improper A/C system operation

• Erratic signal or no signal from CMP sensor

• Air leakage from intake-air system parts

• Improper VIS operation (if equipped)

• Improper VTCS operation

• Purge control solenoid malfunction

• EGR valve malfunction

• Brake dragging

• Erratic signal from CKP sensor

• Low engine compression

• Vacuum leakage

• Poor fuel quality

• Spark leakage from high-tension leads

• Engine overheating

• Throttle body malfunction

• Spark plug malfunction

• Air cleaner restriction

• PCV valve malfunction

• Improper valve timing due to jumping out of timing belt

• Improper variable valve timing control operation (if equipped)

• Restriction in exhaust system

• Intermittent open or short in fuel pump related circuit

• Inadequate fuel pressure

• Fuel pump mechanical malfunction

• Fuel line restriction or clogging

• Fuel leakage from fuel injector

• Fuel injector clogging

• Intermittent open or short of MAF sensor, TP sensor and VSS

• ATX malfunction (ATX)

• Clutch slippage (MTX)

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 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.
(See

F–17 BEFORE REPAIR PROCEDURE

(See

F–17 AFTER REPAIR PROCEDURE

Caution

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

Verify following:

• Vacuum connection

• Air cleaner element

• No air leakage from intake-air system

• No restriction of intake-air system

• Proper sealing of intake manifold and

components attached to intake manifold;
such as EGR valve, IAC valve

• Fuel quality (e.g. proper octane,

contamination, winter/summer blend)

Are all items okay?

Yes

Go to next step.

Service as necessary.
Repeat Step 1.

F–208

TROUBLESHOOTING

Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and
KOER DTCs.
If engine stall condition exists, retrieve
continuous memory and KOEO DTCs.
Are there any DTCs displayed?

Yes

DTC is displayed:
Go to appropriate DTC test.

No DTC is displayed:
Go to next step.

Is engine overheating?

Yes

Go to symptom troubleshooting "No.17 Cooling system
concerns - Overheating".

Go to next step.

Connect WDS or equivalent to DLC-2.
Access RPM, MAF, TP and VSS PIDs.
Drive vehicle while monitoring PIDs.
Are PIDs within specifications?
(See

F–45 PCM INSPECTION

Yes

Go to next step.

RPM PID:
Inspect CKP sensor and related wiring harness for
vibration and/or intermittent open/short circuit.
MAF PID:
Inspect for intermittent open circuit of MAF sensor and
related wiring harness.
TP PID:
Inspect if TP sensor output increases smoothly.
VSS PID:
Inspect for intermittent open circuit of VSS and related
wiring harness.

Visually inspect CKP sensor and teeth of
crankshaft pulley.
Are CKP sensor and teeth of crankshaft pulley
okay?

Yes

Go to next step.

Replace malfunctioning parts.

Measure gap between CKP sensor and teeth of
crankshaft pulley.

Specification

0.5—1.9 mm {0.020—0.075 in}

Is gap within specification?

Yes

Go to next step.

Adjust CKP sensor.

Inspect spark plug condition.
Is spark plug wet, covered with carbon or
grayish white?

Yes

Spark plug is wet or covered with carbon:
Inspect for fuel leakage from fuel injector.
Spark plug is grayish white:
Inspect for clogged fuel injector.

Install spark plugs on original cylinders.
Go to next step.

Remove and shake PCV valve.
Does PCV valve rattle?

Yes

Go to next step.

Replace PCV valve.

Inspect for restriction in exhaust system.
Is there any restriction?

Yes

Inspect exhaust system.

Go to next step.

F–20 FUEL LINE PRESSURE

INSPECTION

)

Yes

Go to next step.

Zero or low:
Inspect for clogged fuel line.
If okay, replace fuel pump unit.
High:
Replace fuel pump unit.

Inspect VTCS operation.
(See

F–231 Variable Tumble Control System

(VTCS) Operation Inspection

Does VTCS work properly?

Yes

Go to next step.

Repair or replace malfunctioning parts.

Note

• The following test should be performed for

vehicles with VIS. Go to next step for
vehicles without VIS.

Inspect VIS operation.
(See

F–230 VIS Operation Inspection

Does VIS work properly?

Yes

Go to next step.

Repair or replace malfunctioning parts.

STEP

INSPECTION

RESULTS

ACTION

TROUBLESHOOTING

F–209

End Of Sie

Note

• Following test is for engine stalling with A/

C on concern. If other symptoms exist, go
to next step.

Connect pressure gauge to A/C low and high
side pressure lines.
Turn A/C on and measure low side and high side
pressures.
Are pressures within specifications?
(See

U–12 REFRIGERANT PRESSURE

CHECK

Yes

Go to next step.

If A/C is always on, go to symptom troubleshooting
"No.24 A/C is always on or A/C compressor runs
continuously".
For other symptoms, inspect following:

• Refrigerant charging amount

• Condenser fan operation

Inspect for A/C cut-off operation.
(See

F–234 A/C Cut-off Control System

Inspection

Does A/C cut-off work properly?

Yes

Go to next step.

Inspect A/C cut-off system components.

Disconnect vacuum hose between purge
solenoid valve and intake manifold from purge
solenoid valve side.
Plug opening end of vacuum hose.
Drive vehicle.
Does engine condition improve?

Yes

Inspect if purge solenoid valve is sticks open
mechanically.
Inspect evaporative emission control system.

Go to next step.

Visually inspect CMP sensor and projections of
camshaft pulley.
Are CMP sensor and projections of camshaft
pulley okay?

Yes

Go to next step.

Replace malfunctioning parts.

Inspect EGR system.
(See

F–233 EGR Control System Inspection

Is EGR system okay?

Yes

Go to next step.

Replace malfunctioning parts.

Note

• The following test should be performed for

vehicles with variable valve timing control
system. Go to next step for vehicles
without variable valve timing control
system.

Inspect variable valve timing control system
operation.
(See

F–239 Variable Valve Timing Control

System Operation Inspection

Does variable valve timing control system work
properly?

Yes

Go to next step.

Repair or replace malfunctioning parts.

Is engine compression correct?

Yes

Inspect following:

• Valve timing

• Internal transaxle components (ATX)

• Clutch (MTX)

• Brake system for dragging

Inspect for cause.

Verify test results.

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

• If malfunction remains, replace PCM.

STEP

INSPECTION

RESULTS

ACTION

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