NO.14 POOR FUEL ECONOMY [MZ-CD 1.6 (Y6)]

14	POOR FUEL ECONOMY
DESCRIPTION	• The fuel economy is unsatisfactory.
POSSIBLE CAUSE	• Incorrect idle speed • A/C system improper operation • Intake -air system clogging or restriction • Engine cooling system malfunction • Poor fuel quality • Improper coolant level • Erratic signal from CKP sensor • Erratic signal from CMP sensor • Fuel pressure sensor or related circuit malfunction • ECT sensor or related circuit malfunction • Boost sensor or related circuit malfunction • Accelerator pedal position sensor or related circuit malfunction • Incorrect adjustment idle switch • MAF/IAT sensor or related circuit malfunction • VSS or related circuit malfunction • Turbocharger malfunction • Charge air cooler malfunction • Low engine compression • Improper valve timing • Exhaust system and/or catalyst converter clogging • Incorrect fuel injection timing • Fuel injector malfunction • Supply pump malfunction • Fuel leakage • Fuel line clogging or restriction • Fuel filter clogging or restriction • Brake dragging • EGR system malfunction • Vacuum leakage • Clutch slippage • Variable boost control (VBC) system malfunction • Coolant heater system malfunction • Diesel particulate filter restriction or damaged (High power-Euro 4) • 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.

POOR FUEL ECONOMY

DESCRIPTION

• The fuel economy is unsatisfactory.

POSSIBLE CAUSE

• Incorrect idle speed

• A/C system improper operation

• Intake -air system clogging or restriction

• Engine cooling system malfunction

• Poor fuel quality

• Improper coolant level

• Erratic signal from CKP sensor

• Erratic signal from CMP sensor

• Fuel pressure sensor or related circuit malfunction

• ECT sensor or related circuit malfunction

• Boost sensor or related circuit malfunction

• Accelerator pedal position sensor or related circuit malfunction

• Incorrect adjustment idle switch

• MAF/IAT sensor or related circuit malfunction

• VSS or related circuit malfunction

• Turbocharger malfunction

• Charge air cooler malfunction

• Low engine compression

• Improper valve timing

• Exhaust system and/or catalyst converter clogging

• Incorrect fuel injection timing

• Fuel injector malfunction

• Supply pump malfunction

• Fuel leakage

• Fuel line clogging or restriction

• Fuel filter clogging or restriction

• Brake dragging

• EGR system malfunction

• Vacuum leakage

• Clutch slippage

• Variable boost control (VBC) system malfunction

• Coolant heater system malfunction

• Diesel particulate filter restriction or damaged (High power-Euro 4)

• 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 and/or restriction • Fuel line leakage • Intake-air system restriction • Exhaust system, catalyst converter and/or diesel particulate filter^* restriction • Charge air cooler condition (restriction or damaged) • Vacuum leakage Are all items normal?	Yes	Go to the next step.
No	Service if necessary. Repeat Step 1.
2	Is the brake system functioning properly?	Yes	Go to the next step.
No	Inspect for the cause.
3	Perform the self-test function using the M-MDS. Turn the engine switch to the ON position. Retrieve any DTC. Are DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC test. Communication error message is displayed: Inspect for the following: • Open circuit between PCM control relay and PCM terminal 53 or 79 • Open circuit between PCM control relay and PCM terminal 69 • PCM control relay stuck open • Open or poor ground circuit (PCM terminal 65, 85, 103 or 104) • 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 vehicle without 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	Access ECT PID. Drive vehicle while monitoring PID. Is PID within specification?	Yes	Go to the next step.
No	Inspect for coolant leakage, cooling fan operations or thermostat operation.
6	Inspect idle speed. Is the idle speed normal?	Yes	Go to the next step.
No	Go to symptom troubleshooting “NO.7 SLOW RETURN TO IDLE”.
7	Perform the EGR system inspection. Is the EGR system normal?	Yes	Go to the next step.
No	Repair or replace malfunctioning part according to the EGR system operation results.
8	Inspect adjustment of accelerator pedal position sensor and idle switch. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZ-CD 1.6 (Y6)].) Are the accelerator pedal position sensor and the idle switch adjusted correctly?	Yes	Go to the next step.
No	Adjust the accelerator pedal position sensor and the idle switch correctly.
9	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.
10	Inspect fuel injector. (See ПРОВЕРКА ТОПЛИВНЫХ ФОРСУНОК [MZ-CD 1.6 (Y6)].) Is fuel injector normal?	Yes	Go to the next step.
No	Repair or replace if necessary.
11	Perform the turbocharger inspection. (See TURBOCHARGER INSPECTION [MZ-CD 1.6 (Y6)].) Is the turbocharger normal?	Yes	Go to the next step.
No	Replace the turbocharger.
12	Inspect guide blade valve operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZ-CD 1.6 (Y6)].) Is there any problem?	Yes	Repair or replace if necessary.
No	Go to the next step.
13	Visually inspect CKP sensor and teeth of pulse wheel. Are the CKP sensor and the teeth of pulse wheel normal?	Yes	Go to the next step.
No	Replace malfunctioning parts.
14	Measure gap between CKP sensor and teeth of pulse wheel. Specification 1.5—2.5 mm {0.059—0.098 in} Is the gap within specification?	Yes	Go to the next step.
No	Adjust the CKP sensor position.
15	Visually inspect CMP sensor and teeth of pulse wheel. Are the CMP sensor and the teeth of pulse wheel normal?	Yes	Inspect the following PIDs: (See PCM INSPECTION [MZ-CD 1.6 (Y6)].) • ECT • IAT • MAF • MAP • RPM • VSS If the PID value is not as specified, repair or replace malfunctioning parts. If the PID value is normal, go to the next step. (High power-Euro 4) or step 21 (standard power-Euro 4)
No	Replace malfunctioning parts.
16	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.
17	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
18	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.
19	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.
20	Access following PIDs using the M-MDS. • CABVDC • CABVP • DPF_DIF 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	Go to the next step.
21	Inspect timing belt for following: • Chipping of gear teeth • Low tension • Breakage damage or cracks Is the timing belt normal?	Yes	Inspect the following: • Clutch slippage • CKP sensor • Boost sensor and related circuit • Brake system for dragging • Coolant heater system • Glow system If normal, remove and inspect the supply pump.
No	If the timing is incorrect, adjust the valve timing. If the timing belt is not normal, replace the timing belt.
22	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 and/or restriction

• Fuel line leakage

• Intake-air system restriction

• Exhaust system, catalyst converter and/or diesel particulate filter^* restriction

• Charge air cooler condition (restriction or damaged)

• Vacuum leakage

Are all items normal?

Yes

Go to the next step.

Service if necessary.

Repeat Step 1.

Is the brake system functioning properly?

Yes

Go to the next step.

Inspect for the cause.

Perform the self-test function using the M-MDS.

Turn the engine switch to the ON position.

Retrieve any DTC.

Are DTCs displayed?

Yes

DTC is displayed:

Go to the appropriate DTC test.

Communication error message is displayed:

Inspect for the following:

• Open circuit between PCM control relay and PCM terminal 53 or 79

• Open circuit between PCM control relay and PCM terminal 69

• PCM control relay stuck open

• Open or poor ground circuit (PCM terminal 65, 85, 103 or 104)

• 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 vehicle without 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.

Access ECT PID.

Drive vehicle while monitoring PID.

Is PID within specification?

Yes

Go to the next step.

Inspect for coolant leakage, cooling fan operations or thermostat operation.

Inspect idle speed.

Is the idle speed normal?

Yes

Go to the next step.

Go to symptom troubleshooting “NO.7 SLOW RETURN TO IDLE”.

Perform the EGR system inspection.

Is the EGR system normal?

Yes

Go to the next step.

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

Inspect adjustment of accelerator pedal position sensor and idle switch.

(See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZ-CD 1.6 (Y6)].)

Are the accelerator pedal position sensor and the idle switch adjusted correctly?

Yes

Go to the next step.

Adjust the accelerator pedal position sensor and the idle switch correctly.

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 fuel injector normal?

Yes

Go to the next step.

Repair or replace if necessary.

Perform the turbocharger inspection.

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

Is the turbocharger normal?

Yes

Go to the next step.

Replace the turbocharger.

Inspect guide blade valve operation.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZ-CD 1.6 (Y6)].)

Is there any problem?

Yes

Repair or replace if necessary.

Go to the next step.

Visually inspect CKP sensor and teeth of pulse wheel.

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

Yes

Go to the next step.

Replace malfunctioning parts.

Measure gap between CKP sensor and teeth of pulse wheel.

Specification

1.5—2.5 mm {0.059—0.098 in}

Is the gap within specification?

Yes

Go to the next step.

Adjust the CKP sensor position.

Visually inspect CMP sensor and teeth of pulse wheel.

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

Yes

Inspect the following PIDs:

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

• ECT

• IAT

• MAF

• MAP

• RPM

• VSS

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

If the PID value is normal, go to the next step. (High power-Euro 4) or step 21 (standard power-Euro 4)

Replace malfunctioning parts.

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

Monitor the PIDs.

Are there any problems detected?

Yes

Inspect the suspect PID related wiring and components.

If okay inspect the fuel level sensor.

Go to the next step.

Inspect timing belt for following:

• Chipping of gear teeth

• Low tension

• Breakage damage or cracks

Is the timing belt normal?

Yes

Inspect the following:

• Clutch slippage

• CKP sensor

• Boost sensor and related circuit

• Brake system for dragging

• Coolant heater system

• Glow system

If normal, remove and inspect the supply pump.

If the timing is incorrect, adjust the valve timing.

If the timing belt is not normal, replace the timing belt.

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)].)