NO.14 POOR FUEL ECONOMY [AJ (3.0L Duratec)]


14	Poor fuel economy
DESCRIPTION	• Fuel economy is unsatisfactory.
POSSIBLE CAUSE	• Contaminated air cleaner element • IMCC malfunction • Engine cooling system malfunction • Improper ATF level • Weak spark • Poor fuel quality • Erratic or no signal from CMP sensor • Improper coolant level • Inadequate fuel pressure • Spark plug malfunction • PCV valve malfunction • Brake dragging • Improper valve timing due to jumping out of timing belt • Contaminated MAF sensor • Improper engine compression • Exhaust system clogging 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 [AJ (3.0L Duratec)].) (See AFTER SERVICE PRECAUTION [AJ (3.0L Duratec)].)


STEP	INSPECTION	RESULTS	ACTION
1	• Inspect following: - Air cleaner element for contamination - ATF level - Fuel quality - Coolant level • Are all items okay?	Yes	Go to the next step.
1		No	Service as necessary. Repeat Step 1.
2	• Connect WDS or equivalent to DLC-2. • Turn key to ON (Engine OFF). • Retrieve any DTCs. • Is "PASSED" displayed?	Yes	No DTC is displayed: • Go to the next step.
2		No	DTC is displayed: • Go to appropriate DTC test.
3	• Access ECT PID. • Drive vehicle while monitoring PID. • Is PID within specification?	Yes	Go to the next step.
3		No	Inspect for coolant leakage. Inspect cooling fan operations or thermostat operations.
4	• Perform the spark test. (See Spark Test) • Is strong blue spark visible at each cylinder?	Yes	Go to the next step.
4		No	Repair or replace malfunctioning part according to spark test result.
5	• Inspect for following ignition control system related parts: - Spark plug (heat range) - CMP sensor installation - CMP sensor trigger wheel damaged (on camshaft) - Open or short circuit on CMP sensor - Open or short circuit between CMP sensor and PCM terminal 85 or 86 (R.H.D.)/E-25 orE-41 (L.H.D.) • Are all items okay?	Yes	Go to the next step.
5		No	Repair or replace malfunctioning part.
6	• Install the fuel pressure gauge to fuel line. • Start the engine run it at idle. • Measure the fuel line pressure at idle. • Is the fuel line pressure correct? (See FUEL LINE PRESSURE INSPECTION [AJ (3.0L Duratec)].)	Yes	Go to the next step.
6		No	Zero or low: Inspect clogged fuel line. • If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [AJ (3.0L Duratec)].)
7	• Inspect IMCC operation. • Does IMCC work properly?	Yes	Go to the next step.
7	• Inspect IMCC operation. • Does IMCC work properly?	No	Repair or replace malfunctioning part.
8	• Remove and shake PCV valve. • Does PCV valve rattle?	Yes	Go to the next step.
8	• Remove and shake PCV valve. • Does PCV valve rattle?	No	Replace PCV valve.
9	• Visually inspect the exhaust system part. • Is there any deformed exhaust system part?	Yes	Replace suspected part.
9		No	Go to the next step.
10	• Is brake system functioning properly?	Yes	Go to the next step.
10	• Is brake system functioning properly?	No	Inspect for cause.
11	• Inspect MAF sensor for contamination. • Is there any contamination?	Yes	Replace MAF sensor.
11		No	Go to the next step.
12	• Is engine compression correct?	Yes	Inspect valve timing.
12	• Is engine compression correct?	No	Inspect for cause.
13	• Verify test results. - If okay, return to diagnostic index to service any additional symptoms. - If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace PCM.