NO.14 POOR FUEL ECONOMY [MZR 2.0 DISI]

id0103d5802000

14

POOR FUEL ECONOMY
DESCRIPTION
•  Fuel economy is unsatisfactory.
POSSIBLE CAUSE
•  Contaminated air cleaner element
•  Air leakage or restriction from intake-air system
•  Poor fuel quality
•  Improper coolant level
•  Clutch slippage (MTX)
•  Improper ATF level (ATX)
•  Brake dragging
•  Vacuum leakage
•  Fuel leakage
•  Contaminated MAF sensor
•  Exhaust system and/or TWC restriction
•  PCM DTC is stored
•  Engine cooling system malfunction
•  EGR system malfunction
•  Variable swirl system malfunction
•  Improper operation of A/C system
•  Spark plug malfunction
•  Erratic or no signal from CMP sensor
•  Erratic signal from CKP sensor
•  Erratic signal to PCM
―  APP sensor or related circuit malfunction
―  ECT sensor or related circuit malfunction
―  IAT sensor or related circuit malfunction
―  MAF sensor or related circuit malfunction
―  MAP sensor or related circuit malfunction
―  Intermittent open or short circuit MAF sensor, APP sensor, TP sensor and VSS
•  Inadequate fuel pressure (high-pressure side)
―  Fuel pressure sensor malfunction
―  High pressure fuel pump malfunction
―  Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system)
―  Spill valve control solenoid valve (built-in high pressure fuel pump) malfunction
―  Relief valve (built-in fuel delivery pipe) malfunction
―  Fuel line restriction or clogging
―  Fuel pump unit malfunction
•  Incorrect fuel injection timing
•  Fuel injector malfunction
•  Improper engine compression
•  Improper valve timing due to jumping out of timing chain
•  PCV valve malfunction
•  Injector driver (built-in PCM) malfunction
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 [MZR 2.0 DISI].) (See AFTER SERVICE PRECAUTION [MZR 2.0 DISI].)
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.

Diagnostic procedure

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
•  Brake dragging
•  Vacuum leakage
•  Fuel leakage
•  MAF sensor contaminated
•  Exhaust system and/or TWC restriction
•  Clutch slippage (MTX)
•  ATF level (ATX)
Is there any malfunction?
Yes
Service if necessary.
•  Repeat this step.
No
Go to the next step.
2
Retrieve any PCM DTCs using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI].)
Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 2.0 DISI].)
No
Go to the next step.
3
Perform the Cooling Fan Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI].)
Does the cooling fan control system operate 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 [MZR 2.0 DISI].)
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 System Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI].)
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 A/C Cut-off Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI].)
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.
7
Perform the Spark Test.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI].)
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.
8
Inspect the CMP sensor and CKP sensor for the following:
•  Installation condition
•  Damaged trigger wheel and camshaft
•  Open or short circuit in related circuit
Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
9
Caution
•  While performing this step, always operate the vehicle in a safe and lawful manner.
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
Access the following PIDs using the M-MDS:
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI].)
•  APP
•  ECT
•  IAT
•  MAF
•  MAP
•  TP
•  VSS
Do the PIDs indicate the correct values under the trouble condition?
(See PCM INSPECTION [MZR 2.0 DISI].)
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
•  If the malfunction remains:
―  Perform the “INTERMITTENT CONCERN TROUBLESHOOTING” procedure.
10
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI].)
Is the FUEL_PRES PID value within the specification?
(See PCM INSPECTION [MZR 2.0 DISI].)
Yes
Go to Step 15.
No
Go to the next step.
11
Is the vehicle accelerate performance normally?
Yes
Go to the next step.
No
Go to Step 13.
12
Inspect the fuel pressure sensor.
(See FUEL PRESSURE SENSOR INSPECTION [MZR 2.0 DISI].)
Is there any malfunction?
Yes
Replace the fuel delivery pipe.
(See FUEL INJECTOR REMOVAL/INSTALLATION [MZR 2.0 DISI].)
No
Go to Step 15.
13
Switch the ignition to off.
Disconnect the high pressure fuel pump and PCM connectors.
Inspect for continuity between high pressure fuel pump terminal A (wiring harness-side) and body ground.
Is there continuity?
Yes
Repair or replace the wiring harness for a possible short to ground.
•  If the malfunction remains:
―  Replace the PCM. (damage to driver in PCM)
No
Go to the next step.
14
Replace the high pressure fuel pump.
(See HIGH PRESSURE FUEL PUMP REMOVAL/INSTALLATION [MZR 2.0 DISI].)
Access the FUEL_PRES PID using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI].)
Is the FUEL_PRES PID value within the specification?
(See PCM INSPECTION [MZR 2.0 DISI].)
Yes
High pressure fuel pump or spill valve control solenoid valve (built-in high pressure fuel pump) malfunction.
•  Symptom troubleshooting is completed.
•  Go to Step 19.
No
Relief valve (built-in fuel delivery pipe) malfunction.
•  Replace the fuel delivery pipe.
15
Connect the fuel pressure gauge between fuel pump and high pressure fuel pump.
Measure the low side fuel pressure.
(See FUEL LINE PRESSURE INSPECTION [MZR 2.0 DISI].)
Is the low side fuel pressure within the specification?
Yes
Go to the next step.
No
Inspect for following:
•  Fuel line restriction
•  Fuel filter clogging
―  If there is any malfunction:
•  Repair or replace the malfunctioning part according to the inspection results.
―  If there is no malfunction:
•  Replace the fuel pump unit.
16
Perform the Fuel Injector Operation Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 2.0 DISI].)
Do the fuel injectors operate properly?
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 [MZR 2.0 DISI].)
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
Service if necessary.
18
Inspect the PCV valve.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [MZR 2.0 DISI].)
Is there any malfunction?
Yes
Replace the PCV valve.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZR 2.0 DISI].)
No
Injector driver is malfunction.
•  Replace the PCM.
If the malfunction remains:
•  Overhaul the engine.
19
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0 DISI].)
•  If a 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, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 2.0 DISI].)