NO.14 POOR FUEL ECONOMY [MZR 1.3, MZR 1.5]

id0103d7802000

14

POOR FUEL ECONOMY
DESCRIPTION
•  Fuel economy is unsatisfactory.
POSSIBLE CAUSE
•  Contaminated air cleaner element
•  Improper ATF level (ATX)
•  Improper CVT fluid level (CVT)
•  Brake dragging
•  Clutch slippage (MTX)
•  Improper coolant level
•  Poor fuel quality
•  Improper CVT operation (CVT)
•  Continuous memory DTC is stored
•  Engine cooling system malfunction
•  A/F sensor malfunction
•  Ignition system malfunction
―  Spark plug malfunction
―  Ignition coil and related wiring harness malfunction
•  Inadequate fuel pressure
―  Pressure regulator malfunction (built-into fuel pump unit)
―  Fuel pump mechanical malfunction
―  Fuel leakage from fuel system
•  Fuel pump unit malfunction
•  Improper operation of variable tumble control
•  Improper operation of variable valve timing control system
•  Restriction in exhaust system
•  Contaminated MAF sensor
•  Improper engine compression
•  PCV valve malfunction
•  Valve timing malfunction
•  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 injuries 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 1.3, MZR 1.5].) (See AFTER SERVICE PRECAUTION [MZR 1.3, MZR 1.5].)
Caution
•  Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to 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 RELATED PART CONDITION
•  Inspect the following:
―  Air cleaner element for contamination
―  ATF level (ATX)
―  CVT fluid level (CVT)
―  Brake dragging
―  Clutch slippage (MTX)
―  Coolant level
―  Fuel quality
―  CVT operation (CVT)
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
Repeat Step 1.
No
Go to the next step.
2
VERIFY PCM DTC
•  Perform the PCM DTC inspection using the M-MDS.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 1.3, MZR 1.5].)
No
Go to the next step.
3
INSPECT COOLING SYSTEM FOR MALFUNCTION
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 ECT PID using the M-MDS.
•  Monitor the ECT PID while driving the vehicle.
•  Is the ECT PID value within the specification?
Yes
Go to the next step.
No
Inspect for coolant leakage, cooling fan operations or thermostat operation.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR 1.3, MZR 1.5].)
(See THERMOSTAT INSPECTION [MZR 1.3, MZR 1.5].)
Repair or replace the malfunctioning part according to the inspection results.
4
INSPECT IGNITION SYSTEM OPERATION
•  Perform the Spark Test.
•  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.
5
INSPECT FUEL LINE PRESSURE
•  Install the fuel pressure gauge between fuel pipe and fuel distributor.
•  Start the engine and idle it.
•  Measure the fuel line pressure during idle.
•  Is there any malfunction?
Yes
Low:
•  Inspect the fuel line for restriction.
―  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. (pressure regulator or fuel pump mechanical malfunction)
High:
•  Replace the fuel pump unit. (pressure regulator malfunction)
No
Go to the next step.
6
INSPECT VARIABLE TUMBLE CONTROL OPERATION
•  Perform the Variable Tumble Control Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
7
INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
•  Perform the Variable Valve Timing Control System Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
8
INSPECT EXHAUST SYSTEM
•  Visually inspect the exhaust system part.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
9
INSPECT MAF SENSOR FOR CONTAMINATION
•  Inspect the MAF sensor for contamination.
•  Is there any contamination?
Yes
Replace the MAF/IAT sensor.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
No
Go to the next step.
10
INSPECT ENGINE COMPRESSION
•  Inspect the engine compression.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
11
INSPECT IF MALFUNCTION CAUSE IS PCV VALVE OR VALVE TIMING
•  Inspect the PCV valve operation.
•  Is there any malfunction?
Yes
Replace the PCV valve and the oil separator as a single unit.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZR 1.3, MZR 1.5].)
No
Inspect the valve timing.
Repair or replace the malfunctioning part according to the inspection results.
12
Verify test results.
•  If normal, return to the diagnostic index to service any additional symptoms.
•  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, replace the PCM.