Chart 12

WARNING: This page is about a different car, the 2004 Ford Pickup Heritage. However, it is still accessible from the selected car via links, so may be relevant.

Poor Fuel Economy

NOTE: Since driving styles can have a significant influence on fuel economy, verify the concern before starting an in-depth diagnosis. Also, the following external factors could contribute to poor fuel economy conditions:

Stop/go driving
Improper tire pressure/size
Vehicle loads (such as trailer towing)
Extended winter warm-up conditions
High speed driving
Improper axle ratio
Road/weather conditions
Aftermarket add-ons
Short run operations
Customer expectations

SYSTEM/COMPONENT	REFERENCE (PINPOINT TEST - BI-FUEL CNG unless noted)
Check The Following PCM PIDs: DPFEGR (if equipped) (hot idle value within 0.15V of KOEO value) LONGFT1 / LONGFT2 (value between -20 and +20) VPWR (value between 10.5 and 17.0 volts, and within 0.5 volt of battery voltage)	DPFEGR PID value not within 0.15V of KOEO value: Refer to INTRODUCTION - CNG, FLEX-FUEL & GASOLINE . LONGFT1 / LONGFT2 value low (-): Continue diagnosis. Concentrate checks in areas that would cause the engine to run rich. LONGFT1 / LONGFT2 value high (+): Continue diagnosis. Concentrate checks in areas that would cause the engine to run lean. VPWR not between 10.5 and 17.0 volts: Refer to the appropriate GENERATORS & REGULATORS article. VPWR between 10.5 and 17.0 volts, but not within 0.5 of battery voltage: CHECK B(+) supply to power relay. CHECK VPWR circuit between PCM and power relay. CHECK PWR GND circuits.
Automatic Transmission/Transaxle	Refer to the appropriate AUTOMATIC TRANSMISSION article.
PCV System	Refer to INTRODUCTION - CNG, FLEX-FUEL & GASOLINE .
Additional Checks: Correct PCM vehicle identification (VID) block information. Refer to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM . Brake drag Contaminated MAF sensor	Refer to the appropriate service information article.
Verify engine operates at normal temperature	Visual (refer to STEP 2: NO DTC(S) PRESENT SYMPTOM CHART INDEX to diagnose any cooling system concerns that are present).
Transmission/Transaxle Fluid Level	Visual.
Secondary Ignition	Refer to INTRODUCTION - CNG, FLEX-FUEL & GASOLINE .
Intake Air System	Refer to INTRODUCTION - CNG, FLEX-FUEL & GASOLINE .
Fuel Delivery System	GO to Pinpoint Test HC .
Exhaust System	Refer to INTRODUCTION - CNG, FLEX-FUEL & GASOLINE .
Base Engine	Refer to appropriate ENGINE article.