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NO.14 POOR FUEL ECONOMY [MZR-CD (RF Turbo)]

BME010300103285

14 | POOR FUEL ECONOMY
--- | ---
DESCRIPTION | • Fuel economy is unsatisfactory.
POSSIBLE CAUSE | • Incorrect adjustment of idle speed • A/C system improper operation • Air cleaner 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
• MAF/IAT sensor or related circuit malfunction
• IAT sensor No.2 or related circuit malfunction
• VSS or related circuit malfunction
• Turbocharger malfunction
• Charge air cooler malfunction
• Improper engine compression
• Improper valve timing
• Exhaust system and/or catalyst converter clogging
• Injection timing is incorrect
• Fuel injector malfunction
• Supply pump malfunction
• Fuel leakage
• Fuel line restriction
• Fuel filter clogging
• Brake dragging
• EGR system malfunction
• EGR water cooler malfunction
• Vacuum leakage
• Clutch slippage
• Glow system malfunction
• Variable boost control (VBC) system malfunction
• Coolant heater system 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-CD (RF Turbo)].)
  (See AFTER SERVICE PRECAUTION [MZR-CD (RF Turbo)].)

Diagnostic Procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Inspect for 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 and/or catalyst converter 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 cause.
3 | Perform self-test function using the WDS or equivalent. Turn the engine switch to the ON position. Retrieve any DTC. Is DTC displayed? | Yes | DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD (RF Turbo)].) Communication error message is displayed: Inspect for the following:
• Open circuit between PCM control relay and PCM terminal 53 or 79
• Open circuit PCM control relay and PCM terminal 69
• PCM control relay stuck open
• Open or poor GND circuit (PCM terminal 65, 85, 103 or 104)
• Poor connection vehicle body GND
No | No DTC is displayed: Go to the next step.
4 |

  Note

  • The following test should be performed on the 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 the vehicle without the A/C system.
Connect a pressure gauge to A/C line.
Turn the blower and A/C switches on.
Is 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". (See NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF Turbo)].) Other symptoms: Inspect the following:
• Refrigerant charging amount
• Main fan and/or additional fan operation.
5 | Access ECT PID. Drive the vehicle while monitoring PID. Is PID within the specification? | Yes | Go to the next step.
No | Inspect for coolant leakage, the cooling fan and the condenser fan operations or the thermostat operation.
6 | Inspect idle speed. (See IDLE SPEED INSPECTION [MZR-CD (RF Turbo)].) Is idle speed normal? | Yes | Go to the next step.
No | Go to symptom troubleshooting "NO.7 SLOW RETURN TO IDLE". (See NO.7 SLOW RETURN TO IDLE [MZR-CD (RF Turbo)].)
7 | Perform the EGR system inspection. Is the EGR system normal? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the EGR system operation results.
8 | Inspect the EGR water cooler for the following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is the EGR water cooler normal? | Yes | Go to the next step.
No | Service if necessary.
9 | Is the engine compression correct? (See COMPRESSION INSPECTION [MZR-CD (RF Turbo)].) | 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 the fuel injector. (See FUEL INJECTOR INSPECTION [MZR-CD (RF Turbo)].) Is the fuel injector normal? | Yes | Go to the next step.
No | Repair or replace if necessary.
11 | Perform the turbocharger inspection. (See TURBOCHARGER INSPECTION [MZR-CD (RF Turbo)].) Is the turbocharger normal? | Yes | Go to the next step.
No | Replace the turbocharger.
12 | Inspect the guide blade valve operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD (RF Turbo)].) Is there any problem? | Yes | Repair or replace if necessary.
No | Go to the next step.
13 | Visually inspect the CKP sensor and teeth of the pulse wheel. Are the CKP sensor and teeth of the pulse wheel normal? | Yes | Go to the next step.
No | Replace malfunctioning the parts.
14 | Measure the gap between the CKP sensor and teeth of the pulse wheel. Specification 1.5-2.5 mm {0.059-0.098 in} Is the gap within the specification? | Yes | Go to the next step.
No | Adjust the CKP sensor position.
15 | Visually inspect the CMP sensor and teeth of the pulse wheel. Are the CMP sensor and teeth of the pulse wheel normal? | Yes | Inspect the following PIDs: (See PCM INSPECTION [MZR-CD (RF Turbo)].) • ECT • IAT • MAF
• MAP
• RPM
• VSS
If PID value is not as specified, repair or replace the malfunctioning part.
If PID value is normal, go to the next step.
No | Replace the malfunctioning part.
16 | Inspect the timing belt for the 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 timing is incorrect, adjust valve timing. If the timing belt is not normal, replace the timing belt.
17 | Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)