No. 14 Poor Fuel Economy

14	POOR FUEL ECONOMY
DESCRIPTION	The fuel consumption is high compared to the customer's expectations or the previous fuel consumption.
Possible cause	NOTE: The perceived poor fuel economy condition has two causes; the vehicle conditions and how the driver uses the vehicle. Especially, it relies heavily on how the driver uses the vehicle. Use of inferior fuel Ethanol blended Lower octane Engine oil malfunction Improper engine oil level Engine oil contamination Improper engine oil viscosity Improper engine compression Ignition system malfunction Improper engine coolant level Improper tire air pressure Improper tires, wheels (large size, irregular size, irregular size) Improper wheel alignment Clutch slippage (MT) Improper ATF level (AT) Brake dragging Engine operation time is longer than traveled distance Vehicle is driven in congested traffic frequently Vehicle left idling for long periods Amount of fuel injection increases Vehicle is carrying excess items (luggage) Frequent acceleration/deceleration Frequently driving uphill Travel distances are short (engine does not warm up)

POOR FUEL ECONOMY

DESCRIPTION

The fuel consumption is high compared to the customer's expectations or the previous fuel consumption.

Possible cause

NOTE:

The perceived poor fuel economy condition has two causes; the vehicle conditions and how the driver uses the vehicle. Especially, it relies heavily on how the driver uses the vehicle.

Use of inferior fuel
- Ethanol blended
- Lower octane
Engine oil malfunction
- Improper engine oil level
- Engine oil contamination
- Improper engine oil viscosity
Improper engine compression
Ignition system malfunction
Improper engine coolant level
Improper tire air pressure
Improper tires, wheels (large size, irregular size, irregular size)
Improper wheel alignment
Clutch slippage (MT)
Improper ATF level (AT)
Brake dragging
Engine operation time is longer than traveled distance
- Vehicle is driven in congested traffic frequently
- Vehicle left idling for long periods
Amount of fuel injection increases
- Vehicle is carrying excess items (luggage)
- Frequent acceleration/deceleration
- Frequently driving uphill
- Travel distances are short (engine does not warm up)

Diagnostic Procedure

Step	INSPECTION	RESULTS	Action
1	VERIFY ALL SYSTEM DTCs NOTE: Display the DTCs of all the modules using the M-MDS. Connect the M-MDS to the DLC-2. After the vehicle is identified, select the following items from the initialization screen of the M-MDS. Select "Self Test". Select "All CMDTCs". Verify the DTC according to the directions on the screen. Are any DTCs present?	Yes	Go to the applicable DTC inspection.
1		No	Go to the next step.
2	VERIFY IF MALFUNCTION SYMPTOM IS CAUSED BY OTHER MALFUNCTION NOTE: There are few malfunction affecting only the fuel economy, therefore it is necessary to verify that other malfunctions are not appearing as symptoms. Verify the vehicle engine condition. Can malfunction symptoms other than "NO. 14 POOR FUEL ECONOMY" be verified?	Yes	Go to the applicable symptom troubleshooting. (See SYMPTOM DIAGNOSTIC INDEX ).
2		No	Go to the next step.
3	INSPECT ENGINE AND VEHICLE CONDITIONS NOTE: Because the vehicle malfunction cannot be verified, it is necessary to inspect the items which may be adversely affecting fuel consumption. Perform the following inspections: Use of inferior fuel Engine oil level (See ENGINE OIL LEVEL INSPECTION ). Engine oil contamination Engine coolant level (See ENGINE COOLANT LEVEL INSPECTION ). Engine compression pressure inspection (See COMPRESSION INSPECTION ). Spark Test (See ENGINE CONTROL SYSTEM OPERATION INSPECTION ). Tire air pressure Wheel alignment (See SUSPENSION TECHNICAL DATA ). Clutch slippage (MT) Improper ATF level (AT) (See AUTOMATIC TRANSMISSION FLUID (ATF) LEVEL ADJUSTMENT ). Brake dragging Is there any malfunction?	Yes	Repair or adjust the malfunctioning location and explain the repair contents to the customer based on the inspection result.
3		No	Go to the next step.
4	VERIFY VEHICLE USE CONDITION NOTE: It is necessary to ask the customer about how they use the vehicle because there is no problem with the inspection items from Step 1 to 3. Verify how the customer uses the vehicle with regard to the following applicable items, and provide the customer some pertinent advice: Tires, wheels (large size) Engine operation time is longer than traveled distance Vehicle is driven in congested traffic frequently Vehicle left idling for long periods Amount of fuel injection increases Vehicle is carrying excess items (luggage) Frequent acceleration/deceleration Frequently driving uphill Travel distances are short (engine does not warm up) Driving frequently at high-altitude Driving frequently during strong winds Use of unrecommended engine oil (leads to inappropriate oil viscosity)	-	Symptom troubleshooting is completed.