NO.9 POOR FUEL ECONOMY [MZ-CD 1.6]

id0103e8854200

9

Poor fuel economy
DESCRIPTION
•  Excessive fuel consumption.
•  Excessive fuel consumption and glow indicator light is flashing.
POSSIBLE CAUSE
•  PCM DTC is detected.
•  Fuel tank fuel level low.
•  Air cleaner element restriction
•  Loose vacuum line(s)/vacuum connections
•  Loose intake-air system hose(s)/hose connections
•  Loose intake-air system tube(s)/tube connections
•  Coolant leakage
•  Oil leakage
•  Fuel leakage
•  Visibly damaged or worn parts
•  Loose or missing nuts or bolts
•  Incorrect or contaminated fuel in fuel tank
•  Electrical connector, wiring harness or component damaged
•  Loose installation fuel gauge sender unit
•  Vehicle overloaded, or excessive wind resistance (roof racks, towing etc).
•  Brakes binding.
•  Slipping clutch.
•  Generator malfunction
•  Low battery voltage
•  Incorrect engine oil.
•  Air ingress into the fuel lines.
•  EGR valve incorrect base setting
•  Erratic signal to PCM
―  MAF sensor signal malfunction
•  Fuel injector malfunction
•  EGR valve incorrect operation
•  Charge air cooler bend collapse
•  Charge air cooler improper installation
•  Exhaust system blocked.
•  Turbocharger malfunction
•  Fuel lines damaged or blocked.
•  Fuel pressure sensor malfunction.
•  Supply pump malfunction
•  Low cylinder compression.
•  Incorrect valve timing.
•  Timing belt/timing sprocket or pulley/sprocket damaged.
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION
1
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 [MZ-CD 1.6].)
No
Go to the next step.
2
VISUALLY INSPECT RELATED PART CONDITION
•  Visually inspect the following:
Mechanical:
―  Fuel level
―  Air cleaner element
―  Vacuum line(s)/vacuum connections
―  Hose(s)/hose connections
―  Tube(s)/tube connections
―  Coolant leaks
―  Oil leaks
―  Fuel system leaks (Fuel filter, fuel supply line(s), fuel return line(s), high-pressure fuel supply line(s), fuel injectors, fuel rail, supply pump, fuel tank, fuel tank ventilation pipe, fuel tank filler pipe)
―  Visibly damaged or worn parts
―  Loose or missing nuts or bolts
―  Contaminated fuel
Electrical:
―  Fuse(s)
―  Relay(s)
―  Loose or corroded connector(s) (PCM, sensor(s), switch(es))
―  Damaged or worn PCM, switch(es) and/or sensor(s)
―  Wiring harness
―   Fuel gauge sender unit installation
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
Repeat Step 2.
No
Go to the next step.
3
DETERMINE IF MALFUNCTION CAUSE IS VEHICLE OVERLOADING/EXCESSIVE WIND RESISTANCE
•  Verify the vehicle equipped part.
•  Is there any following part equipped?
―  Roof lacks
―  Towing
Yes
Explain to the customer that cause is overloading and/or excessive wind resistance.
No
Go to the next step.
4
INSPECT VEHICLE CONDITION
•  Inspect for following:
―  Brake
―  Clutch
―  Battery
―  Generator
•   Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
5
INSPECT ENGINE OIL AND RELATED PARTS CONDITION
•  Inspect for following:
―  External leakage
―  Proper dipstick
―  Proper engine oil viscosity
•   Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results.
No
Go to the next step.
6
DETERMINE IF MALFUNCTION CAUSE IS AIR INGRESS IN FUEL LINE OR OTHER
•  Perform the Fuel Line Air Bleeding.
•  Verify the symptom.
•  Is the symptom solved?
Yes
Troubleshooting is completed.
(Air ingress into the fuel line.)
No
Go to the next step.
7
DETERMINE IF MALFUNCTION CAUSE IS AIR INGRESS IN FUEL LINE OR OTHER
•  Perform the “EXHAUST GAS RECIRCULATION VALVE LEARNED VALUES RESET” and “INTAKE AIR THROTTLE VALVE LEARNED VALUES RESET”.
•  Verify the symptom.
•  Is the symptom solved?
Yes
Troubleshooting is completed.
(EGR valve base setting is incorrect.)
No
Go to the next step.
8
VERIFY CURRENT INPUT SIGNAL STATUS
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 PCM PID MAF using the M-MDS:
•  Monitor the MAF PID while driving the vehicle.
•  Is the MAF PID normal?
Yes
Go to the next step.
No
Inspect the MAF sensor and related wiring harness.
(See MASS AIR FLOW (MAF) SENSOR INSPECTION [MZ-CD 1.6].)
Repair or replace malfunctioning part.
9
INSPECT FUEL INJECTOR
•  Inspect the fuel injector for each cylinder.
•  Are fuel injectors normal?
Yes
Go to the next step.
No
Replace the suspected fuel injector.
(See FUEL INJECTOR REMOVAL/INSTALLATION [MZ-CD 1.6].)
10
INSPECT EGR VALVE OPERATION
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 following PCM PIDs.
―  EGRP
―  SEGRP DSD
•  Monitor the each PID while driving the vehicle.
•  Are PIDs value changing according to driving conditions?
Yes
Go to the next step.
No
Inspect the EGR valve for stuck.
Clean or replace the EGR valve as necessary.
(See EGR VALVE REMOVAL/INSTALLATION [MZ-CD 1.6].)
11
INSPECT EGR COOLER BYPASS VALVE OPERATION
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 following PCM PIDs.
―  EGR_C_BP
―  EGR_C_BP_D
•  Monitor the each PID while driving the vehicle.
•  Are PIDs value changing according to driving conditions?
Yes
Go to the next step.
No
Inspect the EGR cooler bypass valve for stuck.
Clean or replace the EGR cooler bypass valve as necessary.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
12
INSPECT EGR COOLER BYPASS VALVE OPERATION
•  Visually inspect charge air cooler core.
•  Are there excessive bend or collapse detected?
Yes
Replace the charge air cooler as necessary.
No
Go to the next step.
13
INSPECT CHARGE AIR COOLER PIPES
•  Inspect the hose bands between the following parts:
―  Turbocharger compressor housing and air cleaner
―  Turbocharger compressor housing and charge air cooler
•  Are the hose bands loose?
Yes
Retighten the hose bands.
(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
No
Go to the next step.
14
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.
15
VISUALLY INSPECT TURBOCHARGER COMPRESSOR WHEEL
•  Remove parts necessary to inspect the turbocharger without remove the turbocharger.
•  Inspect if the turbocharger compressor wheel is bent, damaged, or interfering with the housing on the vehicle.
•  Is there any malfunction?
Yes
Replace the turbocharger.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
No
Go to the next step.
16
VISUALLY INSPECT TURBOCHARGER COMPRESSOR WHEEL LOCK BOLT
•  Inspect if the turbocharger compressor wheel locknut is loose or has fallen down inside the turbocharger.
•  Is there any malfunction?
Yes
Replace the turbocharger.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
No
Go to the next step.
17
VERIFY TURBOCHARGER COMPRESSOR WHEEL ROTATION
•  Inspect the turbocharger compressor wheel by hand.
•  Does the wheel turn easily and smoothly?
Yes
Go to the next step.
No
Replace the turbocharger.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
18
VISUALLY INSPECT TURBOCHARGER TURBINE WHEEL
•  Inspect if the turbocharger turbine wheel is damaged, cracked or interfering with the housing on the vehicle.
Note
•  Inspect all fins on each turbine wheel.
•  Is there any malfunction?
Yes
Replace the turbocharger.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [MZ-CD 1.6].)
No
Go to the next step.
19
VISUALLY INSPECT TURBOCHARGER TURBINE HOUSING FOR OIL LEAKAGE
•  Is any engine oil found inside the turbocharger turbine housing?
Yes
If the excessive amount of oil is found:
•  Replace the turbocharger.
If the small amount of oil is found:
•  Wipe oil off of the vehicle, then go to the next step.
No
Go to the next step.
20
VISUALLY INSPECT TURBOCHARGER COMPRESSOR HOUSING FOR OIL LEAKAGE
•  Is any engine oil found inside the turbocharger compressor housing?
Yes
Wipe oil off of the vehicle.
•  Reinstall all removed parts in Step 15, then go to the next step.
No
Turbocharger is normal.
•  Reinstall all removed parts in Step 15, then go to the next step.
21
DETERMINE IF MALFUNCTION CAUSE IS SUPPLY PUMP OR OTHER
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 PID using the M-MDS:
―  FRP
―  FRP_DSD
―  FUEL_V_DSD
•  Monitor the each PID while driving the vehicle.
•  Are all PIDs normal?
Yes
Go to the next step.
No
Inspect the fuel pressure sensor and related wiring harness.
(See FUEL PRESSURE SENSOR INSPECTION [MZ-CD 1.6].)
•  If there is malfunction, repair or replace malfunctioning part.
•  If there is no malfunction, replace the supply pump.
22
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, reprogram the PCM if a later calibration is available. Retest.