NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [MZ-CD 1.6 (Y6)]

8	ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION	• The engine speed fluctuates between the specified idle speed and a lower speed and the engine shakes excessively. • The idle speed is too slow and engine shakes excessively.
POSSIBLE CAUSE	• Poor fuel quality • Air leakage from intake-air system • Intake-air system restriction • Incorrect idle speed • Engine overheating • Cooling fan system malfunction • A/C system improper operation • EGR system improper operation • EGR water cooler malfunction • Fuel leakage • Inadequate fuel pressure • Fuel pressure sensor or related circuit malfunction • Fuel metering control system malfunction • Fuel pressure limiter malfunction • Fuel filter clogging • Fuel line restriction • Incorrect fuel injection timing • Erratic signal from CKP sensor • Erratic signal from CMP sensor • ECT sensor or related circuit malfunction • Idle switch misadjustment • Idle switch or related circuit malfunction • Accelerator pedal position sensor or related circuit malfunction • MAF/IAT sensor malfunction • Clutch pedal position switch or related circuit malfunction • Supply pump malfunction • Fuel injector malfunction • Low engine compression • Improper valve timing • Engine compression excessive unbalance for each cylinder • Unbalanced fuel injection amount for each cylinder • Diesel particulate filter system malfunction (High power-Euro 4) Предупреждение 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 injury 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.

ENGINE RUNS ROUGH/ROLLING IDLE

DESCRIPTION

• The engine speed fluctuates between the specified idle speed and a lower speed and the engine shakes excessively.

• The idle speed is too slow and engine shakes excessively.

POSSIBLE CAUSE

• Poor fuel quality

• Air leakage from intake-air system

• Intake-air system restriction

• Incorrect idle speed

• Engine overheating

• Cooling fan system malfunction

• A/C system improper operation

• EGR system improper operation

• EGR water cooler malfunction

• Fuel leakage

• Inadequate fuel pressure

• Fuel pressure sensor or related circuit malfunction

• Fuel metering control system malfunction

• Fuel pressure limiter malfunction

• Fuel filter clogging

• Fuel line restriction

• Incorrect fuel injection timing

• Erratic signal from CKP sensor

• Erratic signal from CMP sensor

• ECT sensor or related circuit malfunction

• Idle switch misadjustment

• Idle switch or related circuit malfunction

• Accelerator pedal position sensor or related circuit malfunction

• MAF/IAT sensor malfunction

• Clutch pedal position switch or related circuit malfunction

• Supply pump malfunction

• Fuel injector malfunction

• Low engine compression

• Improper valve timing

• Engine compression excessive unbalance for each cylinder

• Unbalanced fuel injection amount for each cylinder

• Diesel particulate filter system malfunction (High power-Euro 4)

Предупреждение

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 injury 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.

STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Fuel quality (e.g.: including water contamination, winter/summer blend) • Fuel line/fuel filter clogging • Loose bands on intake-air system • Cracks on intake-air system parts • Intake-air system restriction • Vacuum leakage • Cooling fan system operation Are all items normal?	Yes	Go to the next step.
No	Service if necessary Repeat Step 1.
2	Is the engine overheating?	Yes	Go to symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS—OVERHEATING.”
No	Go to the next step.
3	Connect the M-MDS to the DLC-2. Turn the engine switch to the ON position. Retrieve any DTC. Are DTCs displayed?	Yes	DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for the following: • Open circuit between PCM control relay and PCM terminal 236 or 231 • Open circuit between PCM control relay and PCM terminal 241 • PCM control relay stuck open • Open or poor ground circuit (PCM terminal 307, 308 or 332) • Poorly connected vehicle body ground
No	No DTC is displayed: Go to the next step.
4	Примечание • The following test should be performed on vehicles with the A/C system. If the following test cannot be performed due to engine stalling, go to the next step. • Go to the next step for vehicles without the A/C system. Connect the pressure gauge to the A/C line. Turn the blower and A/C switches on. Is the pressure within the specification?	Yes	Go to the next step.
No	A/C is always on: Go to symptom troubleshooting “NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”. Other symptoms: Inspect the following: • Refrigerant charging amount • Cooling fan operation
5	Depress the accelerator pedal slightly. Crank the engine. Does the engine start now?	Yes	Inspect idle speed.
No	Go to the next step.
6	Connect the M-MDS to the DLC-2. Access the following PID. • APP Verify that the PID value when the accelerator pedal is depressed and/or released. Is PID value normal?	Yes	Go to the next step.
No	Inspect and repair or replace the following parts: • Accelerator pedal position sensor
7	Inspect the clutch pedal position switch. (See CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [MZ-CD 1.6 (Y6)].) Is the clutch pedal position switch normal?	Yes	Go to the next step.
No	Replace the clutch pedal position switch.
8	Inspect for fuel leakage from fuel pipe. Is any fuel leakage found on the fuel pipe?	Yes	Repair or replace if necessary.
No	Go to the next step.
9	Visually inspect the CKP sensor and the teeth of the pulse wheel. Are the CKP sensor and the teeth of the pulse wheel normal?	Yes	Go to the next step.
No	Replace malfunctioning parts.
10	Measure the gap between the CKP sensor and the teeth of the pulse wheel. Specification 1.5—2.5 mm {0.059—0.098 in} Is the gap within the specification?	Yes	Go to the next step.
No	Adjust the CKP sensor position.
11	Visually inspect the CMP sensor and the teeth of the pulse wheel. Are the CMP sensor and the teeth of the pulse wheel normal?	Yes	Inspect the following PIDs: (See PCM INSPECTION [MZ-CD 1.6 (Y6)].) • ECT • IAT • MAF • RPM If the PID value is not as specified, repair or replace malfunctioning parts. If the PID value is normal, go to the next step.
No	Replace malfunctioning parts.
12	Inspect fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [MZ-CD 1.6 (Y6)].) Is fuel pressure normal?	Yes	Go to the next step.
No	Replace the common rail.
13	Inspect fuel metering valve. (See ПРОВЕРКА ДОЗИРУЮЩЕГО КЛАПАНА [MZ-CD 1.6 (Y6)].) Is fuel metering valve normal?	Yes	Go to the next step.
No	Replace the fuel pump. (See СНЯТИЕ И УСТАНОВКА ТНВД [MZ-CD 1.6 (Y6)].)
14	Is the engine compression correct?	Yes	Go to the next step.
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.
15	Inspect fuel injector. (See ПРОВЕРКА ТОПЛИВНЫХ ФОРСУНОК [MZ-CD 1.6 (Y6)].) Is the fuel injector normal?	Yes	Go to the next step.
No	Repair or replace if necessary.
16	Inspect EGR system operation. Is the EGR system operation normal?	Yes	Go to the next step.
No	Repair or replace the malfunctioning parts according to the EGR system operation results.
17	Inspect the EGR water cooler for following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is the EGR water cooler normal?	Yes	Remove and inspect the supply pump and common rail. (High power-Euro 4) Go to the next step.
No	Service if necessary.
18	Check scheduled maintenance for following: • Fuel additive • Diesel particulate filter Are these scheduled maintenances properly?	Yes	Go to the next step.
No	Carry out the scheduled maintenance properly.
19	Inspect the fuel additive amount. Are there any fuel additives in fuel additive tank?	Yes	Go to the next step.
No	Inspect and repair or replace for following: • Fuel additive hose (Fuel additive tank - fuel additive pump - fuel tank) • Fuel tank level sensor
20	Remove the diesel particulate filter. Visually inspect for damaged at diesel particulate filter. Are there detected any damaged?	Yes	Replace the diesel particulate filter.
No	Go to the next step.
21	Perform cooling air bypass valve operation inspection. Does the cooling air bypass valve operation properly?	Yes	Go to the next step.
No	Repair or replace malfunctioning part, according to inspection result.
22	Access following PIDs using the M-MDS. • CABVDC • CABVP • DPF_DIF • POST_CAT Monitor the PIDs. Are there any problems detected?	Yes	Inspect the suspect PID related wiring and components. If okay inspect the fuel level sensor.
No	Remove and inspect the supply pump and the common rail.
23	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZ-CD 1.6 (Y6)].) • If the malfunction remains, inspect related Service Information and perform repair or diagnosis. ― If the vehicle is repaired, troubleshooting is completed. ― If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZ-CD 1.6 (Y6)].)

STEP

INSPECTION

RESULTS

ACTION

Inspect the following:

• Fuel quality (e.g.: including water contamination, winter/summer blend)

• Fuel line/fuel filter clogging

• Loose bands on intake-air system

• Cracks on intake-air system parts

• Intake-air system restriction

• Vacuum leakage

• Cooling fan system operation

Are all items normal?

Yes

Go to the next step.

Service if necessary

Repeat Step 1.

Is the engine overheating?

Yes

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

Go to the next step.

Connect the M-MDS to the DLC-2.

Turn the engine switch to the ON position.

Retrieve any DTC.

Are DTCs displayed?

Yes

DTC is displayed:

Go to appropriate DTC test.

Communication error message is displayed:

Inspect for the following:

• Open circuit between PCM control relay and PCM terminal 236 or 231

• Open circuit between PCM control relay and PCM terminal 241

• PCM control relay stuck open

• Open or poor ground circuit (PCM terminal 307, 308 or 332)

• Poorly connected vehicle body ground

No DTC is displayed:

Go to the next step.

Примечание

• The following test should be performed on vehicles with the A/C system. If the following test cannot be performed due to engine stalling, go to the next step.

• Go to the next step for vehicles without the A/C system.

Connect the pressure gauge to the A/C line.

Turn the blower and A/C switches on.

Is the pressure within the specification?

Yes

Go to the next step.

A/C is always on:

Go to symptom troubleshooting “NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.

Other symptoms:

Inspect the following:

• Refrigerant charging amount

• Cooling fan operation

Depress the accelerator pedal slightly.

Crank the engine.

Does the engine start now?

Yes

Inspect idle speed.

Go to the next step.

Connect the M-MDS to the DLC-2. Access the following PID.

• APP

Verify that the PID value when the accelerator pedal is depressed and/or released.

Is PID value normal?

Yes

Go to the next step.

Inspect and repair or replace the following parts:

• Accelerator pedal position sensor

Inspect the clutch pedal position switch.

(See CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [MZ-CD 1.6 (Y6)].)

Is the clutch pedal position switch normal?

Yes

Go to the next step.

Replace the clutch pedal position switch.

Inspect for fuel leakage from fuel pipe.

Is any fuel leakage found on the fuel pipe?

Yes

Repair or replace if necessary.

Go to the next step.

Visually inspect the CKP sensor and the teeth of the pulse wheel.

Are the CKP sensor and the teeth of the pulse wheel normal?

Yes

Go to the next step.

Replace malfunctioning parts.

Measure the gap between the CKP sensor and the teeth of the pulse wheel.

Specification

1.5—2.5 mm {0.059—0.098 in}

Is the gap within the specification?

Yes

Go to the next step.

Adjust the CKP sensor position.

Visually inspect the CMP sensor and the teeth of the pulse wheel.

Are the CMP sensor and the teeth of the pulse wheel normal?

Yes

Inspect the following PIDs:

(See PCM INSPECTION [MZ-CD 1.6 (Y6)].)

• ECT

• IAT

• MAF

• RPM

If the PID value is not as specified, repair or replace malfunctioning parts.

If the PID value is normal, go to the next step.

Replace malfunctioning parts.

Inspect fuel pressure sensor.

(See FUEL PRESSURE SENSOR INSPECTION [MZ-CD 1.6 (Y6)].)

Is fuel pressure normal?

Yes

Go to the next step.

Replace the common rail.

Inspect fuel metering valve.

(See ПРОВЕРКА ДОЗИРУЮЩЕГО КЛАПАНА [MZ-CD 1.6 (Y6)].)

Is fuel metering valve normal?

Yes

Go to the next step.

Replace the fuel pump.

(See СНЯТИЕ И УСТАНОВКА ТНВД [MZ-CD 1.6 (Y6)].)

Is the engine compression correct?

Yes

Go to the next step.

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.

Inspect fuel injector.

(See ПРОВЕРКА ТОПЛИВНЫХ ФОРСУНОК [MZ-CD 1.6 (Y6)].)

Is the fuel injector normal?

Yes

Go to the next step.

Repair or replace if necessary.

Inspect EGR system operation.

Is the EGR system operation normal?

Yes

Go to the next step.

Repair or replace the malfunctioning parts according to the EGR system operation results.

Inspect the EGR water cooler for following:

• Coolant passage clogging/restriction

• Exhaust gas clogging/restriction

Is the EGR water cooler normal?

Yes

Remove and inspect the supply pump and common rail. (High power-Euro 4)

Go to the next step.

Service if necessary.

Check scheduled maintenance for following:

• Fuel additive

• Diesel particulate filter

Are these scheduled maintenances properly?

Yes

Go to the next step.

Carry out the scheduled maintenance properly.

Inspect the fuel additive amount.

Are there any fuel additives in fuel additive tank?

Yes

Go to the next step.

Inspect and repair or replace for following:

• Fuel additive hose (Fuel additive tank - fuel additive pump - fuel tank)

• Fuel tank level sensor

Remove the diesel particulate filter.

Visually inspect for damaged at diesel particulate filter.

Are there detected any damaged?

Yes

Replace the diesel particulate filter.

Go to the next step.

Perform cooling air bypass valve operation inspection.

Does the cooling air bypass valve operation properly?

Yes

Go to the next step.

Repair or replace malfunctioning part, according to inspection result.

Access following PIDs using the M-MDS.

• CABVDC

• CABVP

• DPF_DIF

• POST_CAT

Monitor the PIDs.

Are there any problems detected?

Yes

Inspect the suspect PID related wiring and components.

If okay inspect the fuel level sensor.

Remove and inspect the supply pump and the common rail.

Verify test results.

• If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZ-CD 1.6 (Y6)].)

• If the malfunction remains, inspect related Service Information and perform repair or diagnosis.

― If the vehicle is repaired, troubleshooting is completed.

― If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZ-CD 1.6 (Y6)].)