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

BME010300000W49

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 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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.

Diagnostic Procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Inspect for 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 okay?
Yes
Go to next step.
No | Service as necessary. Repeat Step 1.
2 | Is brake system functioning properly? | Yes | Go to next step.
No | Inspect for cause.
3 | Perform self-test function using WDS or equivalent. Turn engine switch to ON. Retrieve any DTC. Is DTC displayed? | Yes | DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for 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 next step.
4 |

  Note

  • The following test should be performed on the vehicles with A/C system. If the following test cannot be performed due to engine stalling, go to next step.
  • Go to next step for the vehicle without A/C system.
Connect pressure gauge to A/C line.
Turn blower and A/C switches on.
Is pressure within specifications?

Yes
Go to next step
No | A/C is always on: Go to symptom troubleshooting "NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY". Other symptoms: Inspect following: • Refrigerant charging amount
• Main fan and/or additional fan operation.
5 | Access ECT PID. Drive vehicle while monitoring PID. Is PID within specification? | Yes | Go to next step.
No | Inspect for coolant leakage, cooling fan and condenser fan operations or thermostat operation.
6 | Inspect idle speed. (See IDLE SPEED INSPECTION [MZR-CD (RF Turbo)].) Is idle speed okay? | Yes | Go to next step.
No | Go to symptom troubleshooting "NO.7 SLOW RETURN TO IDLE".
7 | Perform EGR system inspection. Is EGR system okay? | Yes | Go to next step.
No | Repair or replace malfunctioning part according to EGR system operation results.
8 | Inspect EGR water cooler for following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is EGR water cooler okay? | Yes | Go to next step.
No | Service as necessary.
9 | Is engine compression correct? (See COMPRESSION INSPECTION [MZR-CD (RF Turbo)].) | Yes | Go to next step.
No | Inspect for 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 as necessary.
10 | Inspect fuel injector. (See FUEL INJECTOR INSPECTION [MZR-CD (RF Turbo)].) Is fuel injector okay? | Yes | Go to next step.
No | Repair or replace as necessary.
11 | Perform turbocharger inspection. (See TURBOCHARGER INSPECTION [MZR-CD (RF Turbo)].) Is turbocharger okay? | Yes | Go to next step.
No | Replace turbocharger.
12 | Inspect guide blade valve operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZR-CD (RF Turbo)].) Is there any problem? | Yes | Repair or replace as necessary.
No | Go to next step.
13 | Visually inspect CKP sensor and teeth of pulse wheel. Are CKP sensor and teeth of pulse wheel okay? | Yes | Go to next step.
No | Replace malfunctioning parts.
14 | Measure gap between CKP sensor and teeth of pulse wheel. Specification 1.5-2.5 mm {0.059-0.098 in} Is gap within specification? | Yes | Go to next step.
No | Adjust CKP sensor position.
15 | Visually inspect CMP sensor and teeth of pulse wheel. Are CMP sensor and teeth of pulse wheel okay? | Yes | Inspect 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 malfunctioning parts.
If PID value is okay, go to next step.
No | Replace malfunctioning parts.
16 | Inspect timing belt for following: • Chipping of gear teeth • Low tension • Breakage damage or cracks Is timing belt okay? | Yes | Inspect following: • Clutch slippage • CKP sensor • Boost sensor and related circuit • Brake system for dragging
• Coolant heater system
• Glow system
If okay, remove and inspect supply pump.
No | If timing is incorrect, adjust valve timing. If timing belt is not okay, replace timing belt.
17 | Verify test results. • If okay, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)