Content .. 91 92 93 94 ..

Mazda Protege 5. Manual - part 93

SYMPTOM TROUBLESHOOTING [ENGINE CONTROL SYSTEM (ZM)]

01–03A–25

01–03A

NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [ZM]

A3U010318881W50

Diagnostic procedure

Engine runs rough/rolling idle

DESCRIPTION

•

Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively.

•

Idle speed is too slow and engine shakes excessively.

POSSIBLE

CAUSE

•

Air leakage from intake-air system parts

•

A/C system improper operation

•

Spark leakage from high-tension leads

•

Purge solenoid valve malfunction

•

IAC valve improper operation

•

EGR valve malfunction

•

Erratic or no signal from CMP sensor

•

Low engine compression

•

Erratic signal from CKP sensor

•

Poor fuel quality

•

PCV valve malfunction

•

Air cleaner restriction

•

Restriction in exhaust system

•

Disconnected electrical connectors

•

Inadequate fuel pressure

•

Fuel pump mechanical malfunction

•

Fuel leakage from fuel injector

•

Fuel injector clogging

•

Engine overheating

•

Vacuum leakage

•

Pressure regulator control (PRC) system malfunction

Warning
The following troubleshooting flowchart contains fuel system diagnosis and repair procedures.
Read following warnings before performing 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 01–14–4 BEFORE REPAIR PROCEDURE.)
(See 01–14–5 AFTER REPAIR PROCEDURE.)

STEP

INSPECTION

ACTION

•

Inspect for following:
— External fuel shut off or accessory (kill

switch, alarm etc.)

— Fuel quality: proper octane,

contamination, winter/summer blend

— No air leakage from intake-air system
— Proper sealing of intake manifold and

components attached to intake manifold:
EGR valve, IAC valve

— Ignition wiring
— Electrical connections
— Fuses
— Smooth operation of throttle

•

Are all items okay?

Yes

Go to next step.

Service as necessary.
Repeat Step 1.

•

Connect WDS or equivalent to DLC-2.

•

Turn ignition switch on.

•

Retrieve any DTC.

•

Is “DTC” displayed?

Yes

No DTC is displayed:

•

Go to next step.

DTC is displayed:

•

Go to appropriate DTC test.

•

Is engine overheating?

Yes

Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS - OVERHEATING [ZM]”.

Go to next step.

1712-1U-01G(01-03A).fm 25 ページ２００１年６月２９日金曜日午後４時４５分

SYMPTOM TROUBLESHOOTING [ENGINE CONTROL SYSTEM (ZM)]

01–03A–26

Note

•

Following test is for engine running rough
idle with A/C on concerns. If other
symptoms exist, go to next step.

•

Connect pressure gauge to A/C low and high
pressure side lines.

•

Start engine and run it at idle.

•

Turn A/C switch on.

•

Measure low side and high side pressures.

•

Are reading pressures within specifications?
(See 07–10–3 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/A/C COMPRESSOR RUNS
CONTINUOUSLY [ZM]”.
For other symptoms, inspect following:

•

Refrigerant charging amount

•

Condenser fan operation

•

Start engine and run it at idle.

•

Turn steering wheel right to left.

•

Does engine running rough exist while
turning steering wheel right to left?

Yes

Inspect power steering pressure switch operation and wiring
harness between power steering pressure switch connector
and PCM connector terminal 31.

Go to next step.

•

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.

Gap
0.5—1.5 mm {0.020—0.059 in}

•

Is gap within specification?

Yes

Go to next step.

Adjust CKP sensor.

•

Inspect for cracks on high-tension leads.

•

Are there any cracks on high-tension leads?

Yes

Repair suspected high-tension leads.

Go to next step.

•

Inspect spark plug conditions.

•

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

Yes

Spark plug is wet or covered with carbon:

•

Inspect for fuel leakage from injector.

Spark plug is grayish white:

•

Inspect for clogged fuel injector.

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

•

Start engine and disconnect IAC valve
connector.

•

Does rpm drop or engine stall?

Yes

Go to next step.

Inspect IAC valve and wiring harness.

•

Install fuel pressure gauge between fuel filter
and fuel distributor.

•

Start engine and run it at idle.

•

Measure fuel line pressure at idle.

•

Is fuel line pressure correct at idle?

Fuel line pressure
210—250 kPa {2.1—2.6 kgf/cm

, 30—36 psi}

Yes

Go to next step.

Zero or low:

•

Inspect fuel pump circuit.

•

Inspect for open fuel pump relief valve.

•

Inspect for fuel leakage inside pressure regulator.

•

Inspect for clogged main fuel line.

•

Inspect PRC solenoid valve and related vacuum hose
and harness.

High:

•

Inspect pressure regulator for high pressure cause.

•

Inspect for clogged fuel return line.

•

Visually inspect for fuel leakage at fuel
injector, O-ring, and fuel line.

•

Service as necessary.

•

Does fuel line pressure hold after ignition
switch is turned off?
(See 01–14–28 Operation Inspection.)

Yes

Go to next step.

Inspect pressure regulator diaphragm condition.

•

If condition is okay, inspect fuel injector.

•

If condition is not okay, replace pressure regulator.

•

Connect WDS or equivalent to DLC-2.

•

Start engine and run it at idle.

•

Access LONGFT1 PID.

•

Measure LONGFT1 PID at idle.

•

Is PID value between –25% and +25%?

Yes

Go to next step.

LONGFT1 PID is out of specification.

Less than specification (too rich):

•

Inspect evaporative emission control system.

•

If system is okay, go to Step 15.

Greater than specification (too lean):

•

Inspect for air leakage at intake-air system components.

•

If system okay, go to next step.

STEP

INSPECTION

ACTION

1712-1U-01G(01-03A).fm 26 ページ２００１年６月２９日金曜日午後４時４５分

SYMPTOM TROUBLESHOOTING [ENGINE CONTROL SYSTEM (ZM)]

01–03A–27

01–03A

End Of Sie

NO.9 FAST IDLE/RUNS ON [ZM]

A3U010318881W51

Diagnostic procedure

End Of Sie

•

Disconnect vacuum hose between purge
solenoid valve and intake manifold from
purge solenoid valve side.

•

Plug opening end of vacuum hose.

•

Start engine.

•

Does engine condition improve?

Yes

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

Go to next step.

•

Remove and shake PCV valve.

•

Does PCV valve rattle?

Yes

Go to next step.

Replace PCV valve.

•

Is there any restriction in exhaust system?

Yes

Inspect exhaust 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 engine condition while tapping EGR
valve housing.

•

Does engine condition improve?

Yes

Replace EGR valve.

Go to next step.

•

Is engine compression correct?

Yes

Inspect valve timing.

Inspect for causes.

•

Verify test results.
— If okay, return to diagnostic index to service any additional symptoms.
— If malfunction remains, refer to related Service Bulletins and perform repair or diagnosis.

•

If vehicle is repaired, troubleshooting completed.

•

If vehicle is not repaired or additional diagnostic information is not available, replace PCM.

STEP

INSPECTION

ACTION

Fast idle/runs on

DESCRIPTION

•

Engine speed continues at fast idle after warm-up.

•

Engine runs after ignition switch is turned off.

POSSIBLE

CAUSE

•

ECT sensor malfunction

•

Air leakage from intake-air system

•

Throttle body malfunction

•

Accelerator cable free play misadjustment

•

Cruise control cable misadjustment

STEP

INSPECTION

ACTION

•

Connect WDS or equivalent to DLC-2.

•

Access ECT PID.

•

Start and warm-up engine to normal
operating temperature.

•

Is ECT PID reading between 82—112

°°°°

{180—234

°°°°

F}?

Yes

Go to next step.

ECT PID is higher than 112

°°°°

C {233.6

°°°°

F}:

•

Go to symptom troubleshooting “NO.17 COOLING
SYSTEM CONCERNS — OVERHEATING [ZM]”.

ECT PID is less than 82

°°°°

C {180

°°°°

F}:

•

Go to symptom troubleshooting “NO.18 COOLING
SYSTEM CONCERNS — RUNS COLD [ZM]”.

•

Connect WDS or equivalent to DLC-2.

•

Turn ignition switch on.

•

Retrieve any DTC.

•

Is “DTC” displayed?

Yes

DTC is displayed:

•

Go to appropriate DTC test.

No DTC is displayed:

•

Go to next step.

•

Is there air leakage felt or heard at intake-air
system components while racing engine to
higher speed?

Yes

Repair or replace parts as necessary.

Inspect accelerator cable free play.
(See 01–13A–13 ACCELERATOR CABLE INSPECTION/
ADJUSTMENT [ZM].)

•

Verify test results.
— If okay, return to diagnostic index to service any additional symptoms.
— If malfunction remains, refer to related Service Bulletins and perform repair or diagnosis.

•

If vehicle is repaired, troubleshooting completed.

•

If vehicle is not repaired or additional diagnostic information is not available, replace PCM.

1712-1U-01G(01-03A).fm 27 ページ２００１年６月２９日金曜日午後４時４５分

SYMPTOM TROUBLESHOOTING [ENGINE CONTROL SYSTEM (ZM)]

01–03A–28

NO.10 LOW IDLE/STALLS DURING DECELERATION [ZM]

A3U010318881W52

Diagnostic procedure

End Of Sie

Low idle/stalls during deceleration

DESCRIPTION

•

Engine stops unexpectedly at beginning of deceleration or recovery from deceleration.

POSSIBLE

CAUSE

•

Vacuum leakage

•

IAC valve malfunction

•

Air leakage from intake-air system

•

TP sensor or related circuit malfunction

•

MAF sensor or related circuit malfunction

•

Brake switch or related circuit malfunction

•

Neutral/clutch switch or related circuit malfunction (MTX)

STEP

INSPECTION

ACTION

•

Does engine idle rough?

Yes

Go to symptom troubleshooting “NO.8 ENGINE RUNS
ROUGH/ROLLING IDLE [ZM]”.

Go to next step.

•

Inspect for following:
— Proper routing and no damage of vacuum

lines

— IAC valve is connected properly.
— No air leakage from intake-air system

•

Are all items okay?

Yes

Go to next step.

Service as necessary.
Repeat Step 2.

•

Connect WDS or equivalent to DLC-2.

•

Turn ignition switch on.

•

Retrieve any DTC.

•

Is “DTC” displayed?

Yes

DTC is displayed:

•

Go to appropriate DTC test.

No DTC is displayed:

•

Go to next step.

•

Does idle speed drop or stall when
disconnecting IAC valve?

Yes

Go to next step.

Inspect following:

•

Circuit from IAC valve to PCM connector terminal 54 or
83 for open and short

•

IAC valve for sticking
— If okay, go to next step.

•

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 evaporative emission control system.

Go to next step.

•

Connect WDS or equivalent to DLC-2.

•

Access TP, MAF, VSS PIDs.

•

Monitor each PID while driving vehicle.

•

Are PIDs okay?

Yes

Go to symptom troubleshooting “NO.29 INTERMITTENT
CONCERNS [ZM]”.

TP PID:

•

Inspect TP sensor.

MAF PID:

•

Inspect MAF sensor.

VSS PID:

•

Inspect VSS.

•

Verify test results.
— If okay, return to diagnostic index to service any additional symptoms.
— If malfunction remains, refer to related Service Bulletins and perform repair or diagnosis.

•

If vehicle is repaired, troubleshooting completed.

•

If vehicle is not repaired or additional diagnostic information is not available, replace PCM.

1712-1U-01G(01-03A).fm 28 ページ２００１年６月２９日金曜日午後４時４５分

Content .. 91 92 93 94 ..