NO.14 POOR FUEL ECONOMY [L3 Turbo]

14	POOR FUEL ECONOMY
DESCRIPTION	• Fuel economy is unsatisfactory.
POSSIBLE CAUSE	• Contaminated air cleaner element • Engine cooling system malfunction • Improper ATF level (ATX) • Clutch slippage (MTX) • Weak spark • Spark plug malfunction • Poor fuel quality • Erratic signal from CKP sensor • Erratic or no signal from CMP sensor • Fuel pressure sensor or related circuit malfunction • ECT sensor or related circuit malfunction • MAP sensor or related circuit malfunction • APP sensor or related circuit malfunction • MAF sensor or related circuit malfunction • Contaminated MAF sensor • IAT sensor or related circuit malfunction • Boost air temperature sensor or related circuit malfunction • VSS or related circuit malfunction • Variable swirl system malfunction • Improper coolant level • Inadequate fuel pressure (high-pressure side) • Injection timing is incorrect • Fuel injector or related circuit malfunction • High pressure fuel pump malfunction • Fuel leakage • Fuel line restriction • Fuel filter clogging • PCV valve malfunction • Brake dragging • A/C system improper operation • Improper valve timing due to jumping out of timing chain • Improper engine compression • Turbocharger malfunction • Charge air cooler malfunction • Exhaust system and/or TWC clogging • EGR system malfunction • Vacuum leakage 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 SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [L3 Turbo].) (See AFTER SERVICE PRECAUTION [L3 Turbo].) 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.

POOR FUEL ECONOMY

DESCRIPTION

• Fuel economy is unsatisfactory.

POSSIBLE CAUSE

• Contaminated air cleaner element

• Engine cooling system malfunction

• Improper ATF level (ATX)

• Clutch slippage (MTX)

• Weak spark

• Spark plug malfunction

• Poor fuel quality

• Erratic signal from CKP sensor

• Erratic or no signal from CMP sensor

• Fuel pressure sensor or related circuit malfunction

• ECT sensor or related circuit malfunction

• MAP sensor or related circuit malfunction

• APP sensor or related circuit malfunction

• MAF sensor or related circuit malfunction

• Contaminated MAF sensor

• IAT sensor or related circuit malfunction

• Boost air temperature sensor or related circuit malfunction

• VSS or related circuit malfunction

• Variable swirl system malfunction

• Improper coolant level

• Inadequate fuel pressure (high-pressure side)

• Injection timing is incorrect

• Fuel injector or related circuit malfunction

• High pressure fuel pump malfunction

• Fuel leakage

• Fuel line restriction

• Fuel filter clogging

• PCV valve malfunction

• Brake dragging

• A/C system improper operation

• Improper valve timing due to jumping out of timing chain

• Improper engine compression

• Turbocharger malfunction

• Charge air cooler malfunction

• Exhaust system and/or TWC clogging

• EGR system malfunction

• Vacuum leakage

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 SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual. (See BEFORE SERVICE PRECAUTION [L3 Turbo].) (See AFTER SERVICE PRECAUTION [L3 Turbo].)

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.

STEP	INSPECTION	RESULTS	ACTION
1	Inspect for the following: • Air cleaner element for contamination • Intake-air system restriction • Fuel quality (proper octane, contamination, winter/summer blend) • Coolant level • ATF level (ATX) • Clutch slippage (MTX) • Brake dragging • Charge air cooler condition (restriction or damaged) • Vacuum leakage • Fuel leakage • MAF sensor contaminated • Exhaust system and/or TWC restriction Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Repeat this step.
No	Go to the next step.
2	Turn the ignition switch to the ON position. Retrieve any DTCs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [L3 Turbo].)
No	Go to the next step.
3	Perform the Cooling Fan Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the cooling fan system work properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
4	Perform the EGR Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the EGR system operate properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
5	Perform the Variable Swirl Control System Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the variable swirl system work properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
6	Perform the Wastegate Control System Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the wastegate control system work properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
7	Perform the A/C Cut-off Control System Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Does the A/C cut-off operation work properly?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
8	Perform the Spark Test. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
9	Inspect the CMP and CKP sensor for the following: • Installation condition (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) • Damaged trigger wheel and camshaft • Open or short circuit in the wiring harnesses Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results.
No	Go to the next step.
10	Access the following PIDs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].) • BAT • ECT • MAF • IAT • APP1 • APP2 • TP REL • MAP • VSS Do the PIDs indicate the correct values under trouble condition? (See PCM INSPECTION [L3 Turbo].)	Yes	Go to the next step.
No	Inspect the suspected parts and related wiring harness. • If normal: ― Perform the “INTERMITTENT CONCERN TROUBLESHOOTING” procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3 Turbo].) • If not: ― Repair or replace the malfunctioning part according to the inspection results.
11	Access the FUEL_PRES PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].) Is the FUEL_PRES PID value within the specification? (See PCM INSPECTION [L3 Turbo].)	Yes	Go to Step 15.
No	Go to the next step.
12	Is the vehicle accelerate performance normally?	Yes	Go to the next step.
No	Go to Step 14.
13	Inspect the fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [L3 Turbo].) Is there any malfunction?	Yes	Replace the fuel delivery pipe. (See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)
No	Go to Step 15.
14	Replace the high pressure fuel pump. (See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [L3 Turbo].) Access the FUEL_PRES PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].) Is the FUEL_PRES PID value within the specification? (See PCM INSPECTION [L3 Turbo].)	Yes	High pressure fuel pump or spill valve control solenoid valve (built-in high pressure fuel pump) malfunction. • Go to Step 19.
No	Relief valve malfunction. • Replace the fuel delivery pipe. (See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)
15	Inspect the turbocharger. (See TURBOCHARGER INSPECTION [L3 Turbo].) Is there any malfunction?	Yes	Replace the turbocharger. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L3 Turbo].)
No	Go to the next step.
16	Perform the Fuel Injector Operation Inspection. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].) Do the fuel injectors operate normally?	Yes	Go to the next step.
No	Repair or replace the malfunctioning part according to the inspection results.
17	Measure the compression pressure for each cylinder. (See COMPRESSION INSPECTION [L3 Turbo].) Are the compression pressures within the specification?	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 Repair or replace the malfunctioning part according to the inspection results.
18	Inspect the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [L3 Turbo].) Is there any malfunction?	Yes	Replace the PCV valve. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [L3 Turbo].)
No	Replace the PCM (injector driver circuit malfunction). (See PCM REMOVAL/INSTALLATION [L3 Turbo].) • If the problem remains: ― Repair or replace the malfunctioning part according to the inspection results.
19	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [L3 Turbo].) • If the malfunction remains, inspect the related Service 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

Inspect for the following:

• Air cleaner element for contamination

• Intake-air system restriction

• Fuel quality (proper octane, contamination, winter/summer blend)

• Coolant level

• ATF level (ATX)

• Clutch slippage (MTX)

• Brake dragging

• Charge air cooler condition (restriction or damaged)

• Vacuum leakage

• Fuel leakage

• MAF sensor contaminated

• Exhaust system and/or TWC restriction

Is there any malfunction?

Yes

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

Repeat this step.

Go to the next step.

Turn the ignition switch to the ON position.

Retrieve any DTCs using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].)

Are any DTCs present?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [L3 Turbo].)

Go to the next step.

Perform the Cooling Fan Control System Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the cooling fan system work properly?

Yes

Go to the next step.

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

Perform the EGR Control System Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the EGR system operate properly?

Yes

Go to the next step.

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

Perform the Variable Swirl Control System Operation Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the variable swirl system work properly?

Yes

Go to the next step.

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

Perform the Wastegate Control System Operation Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the wastegate control system work properly?

Yes

Go to the next step.

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

Perform the A/C Cut-off Control System Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Does the A/C cut-off operation work properly?

Yes

Go to the next step.

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

Perform the Spark Test.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Is a strong blue spark visible at each cylinder?

Yes

Go to the next step.

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

Inspect the CMP and CKP sensor for the following:

• Installation condition (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].) (See CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [L3 Turbo].)

• Damaged trigger wheel and camshaft

• Open or short circuit in the wiring harnesses

Is there any malfunction?

Yes

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

Go to the next step.

Access the following PIDs using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].)

• BAT

• ECT

• MAF

• IAT

• APP1

• APP2

• TP REL

• MAP

• VSS

Do the PIDs indicate the correct values under trouble condition?

(See PCM INSPECTION [L3 Turbo].)

Yes

Go to the next step.

Inspect the suspected parts and related wiring harness.

• If normal:

― Perform the “INTERMITTENT CONCERN TROUBLESHOOTING” procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3 Turbo].)

• If not:

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

Access the FUEL_PRES PID using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].)

Is the FUEL_PRES PID value within the specification?

(See PCM INSPECTION [L3 Turbo].)

Yes

Go to Step 15.

Go to the next step.

Is the vehicle accelerate performance normally?

Yes

Go to the next step.

Go to Step 14.

Inspect the fuel pressure sensor.

(See FUEL PRESSURE SENSOR INSPECTION [L3 Turbo].)

Is there any malfunction?

Yes

Replace the fuel delivery pipe.

(See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)

Go to Step 15.

Replace the high pressure fuel pump.

(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [L3 Turbo].)

Access the FUEL_PRES PID using the M-MDS.

(See ON-BOARD DIAGNOSTIC TEST [L3 Turbo].)

Is the FUEL_PRES PID value within the specification?

(See PCM INSPECTION [L3 Turbo].)

Yes

High pressure fuel pump or spill valve control solenoid valve (built-in high pressure fuel pump) malfunction.

• Go to Step 19.

Relief valve malfunction.

• Replace the fuel delivery pipe. (See FUEL INJECTOR REMOVAL/INSTALLATION [L3 Turbo].)

Inspect the turbocharger.

(See TURBOCHARGER INSPECTION [L3 Turbo].)

Is there any malfunction?

Yes

Replace the turbocharger.

(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [L3 Turbo].)

Go to the next step.

Perform the Fuel Injector Operation Inspection.

(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L3 Turbo].)

Do the fuel injectors operate normally?

Yes

Go to the next step.

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

Measure the compression pressure for each cylinder.

(See COMPRESSION INSPECTION [L3 Turbo].)

Are the compression pressures within the specification?

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

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

Inspect the PCV valve.

(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [L3 Turbo].)

Is there any malfunction?

Yes

Replace the PCV valve.

(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [L3 Turbo].)

Replace the PCM (injector driver circuit malfunction).

(See PCM REMOVAL/INSTALLATION [L3 Turbo].)

• If the problem remains:

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

Verify test results.

• If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [L3 Turbo].)

• If the malfunction remains, inspect the related Service 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.