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No. 14 Poor Fuel Economy: Notes

NO. 14 POOR FUEL ECONOMY (SKYACTIV-G 2.0, SKYACTIV-G 2.5)

14	POOR FUEL ECONOMY
DESCRIPTION	Fuel economy is unsatisfactory.
POSSIBLE CAUSE	Engine cooling system malfunction PCM DTC is stored Erratic signal to PCM APP sensor or related circuit malfunction ECT sensor No. 1 or related circuit malfunction IAT sensor No. 1 (integrated in MAF sensor/I AT sensor No. 1) or related circuit malfunction MAF sensor or related circuit malfunction MAP sensor or related circuit malfunction TP sensor or related circuit malfunction Intermittent open or short circuit MAF sensor, APP sensor, TP sensor Improper operation of cooling fan control system Improper operation of A/C system Incorrect fuel injection timing Fuel injector malfunction Short to power supply in wiring harness between IG1 relay terminal C and PCM terminal 2H Contaminated air cleaner element Air leakage or restriction in intake-air system Poor fuel quality Improper coolant level Clutch slippage (MTX) Improper ATF level (ATX) Brake dragging Tire air pressure malfunction Vacuum leakage Fuel leakage Contamination in MAF sensor Tires, wheels (large size) Change of intake air system components and exhaust system components Engine operation time is longer than traveled distance Vehicle is driven in congested traffic frequently Left idling for long periods Amount of fuel injection increases Overloaded Frequent acceleration/deceleration Frequently driving on ascending roads Travel distance per one drive is short (amount of time for warm-up is long during engine operation) Improper load signal input Improper A/C request signal Driver forgets to switch electronic device off Electronic device is frequently used with engine stopped (no power generation) Vehicle left undriven for long periods Large amount of parasitic draw (especially after-market electronic devices) Erratic or no signal from CMP sensor Loose installation Damaged trigger wheel (intake camshaft and/or exhaust camshaft) Open or short circuit in related wiring harness Erratic signal from CKP sensor Loose installation Damaged trigger wheel (crankshaft pulley) Open or short circuit in related wiring harness Inadequate fuel pressure (high-pressure side) Fuel pressure sensor malfunction High pressure fuel pump malfunction Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system) Spill valve control solenoid valve (built-into high pressure fuel pump) malfunction Relief valve (built-into high pressure fuel pump) malfunction Fuel line restricted Fuel pump unit malfunction Improper engine compression Improper intake valve timing due to timing chain jumping Improper exhaust valve timing due to timing chain jumping Spark plug malfunction Exhaust system and/or TWC restriction PCV valve malfunction Injector driver (built-into PCM) 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 .) (See AFTER SERVICE PRECAUTION .) CAUTION: Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign matter.
Courtesy of MAZDA MOTORS CORP.

CAUTION:

Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.

RELATED PIDS

Item (definition)	Unit/Condition	Definition	Condition/Specification (Reference)
AC_REQ	Off/On	A/C request signal	A/C switch off: Off A/C switch on: On
APP1	%	APP sensor No. 1	Accelerator pedal released: Approx. 15% Accelerator pedal depressed: Approx. 82%
APP1	V	APP sensor No. 1	Accelerator pedal released: Approx. 0.75 V Accelerator pedal depressed: Approx. 4.1 V
APP2	%	APP sensor No. 2	Accelerator pedal released: Approx. 7.45% Accelerator pedal depressed: Approx. 41%
APP2	V	APP sensor No. 2	Accelerator pedal released: Approx. 0.38 V Accelerator pedal depressed: Approx. 2.05 V
ECT	°C, °F	Engine coolant temperature (No. 1)	Displays ECT
ECT	V	Engine coolant temperature (No. 1)	ECT is 20 °C {68 °F}: Approx. 3.10 V ECT is 40 °C {104 °F}: Approx. 2.16 V ECT is 60 °C {140 °F}: Approx, 1.40 V ECT is 80 °C {176 °F}: Approx. 0.87 V ECT is 100 °C {212 °F}: Approx. 0.54 V
FUEL_PRES	KPa {MPa}, mBar {Bar}, psi, in H20	Fuel pressure	Displays fuel pressure
FUEL_PRES	V	Fuel pressure	Fuel pressure is 3.0 MPa {31 kgf/cm² , 435 psi}: Approx. 0.92 V Fuel pressure is 4.8 MPa {49 kgf/cm² , 696 psi}: Approx. 1.17 V
IAT	°C, °F	Intake air temperature (No. 1)	Displays IAT (No. 1)
IAT	V	Intake air temperature (No. 1)	IAT is 20 °C {68 °F}: Approx. 2.70 V IAT is 40 °C {104 °F}: Approx. 1.80 V IAT is 60 °C {140 °F}: Approx. 1.20 V
LOAD	%	Engine load	Idle (after warm up): Approx. 16.07% Racing (engine speed is 2, 000 rpm): Approx. 14.51% Racing (engine speed is 4, 000 rpm): Approx. 21.17%
MAF	g/Sec	Mass air flow	Displays MAF
MAF	V	Mass air flow	Switch ignition ON (MAF: 0.59 g/s {0.078 lb/min}): Approx. 0.72 V Idle (after warm up) (MAF: 2.17 g/s {0.287 lb/min}): Approx. 0.86 V Racing (engine speed is 2, 000 rpm) (MAF: 4.73 g/s {0.626 lb/min}): Approx. 1.07 V
MAP	KPa {MPa}, mBar {Bar}, psi, in H20	Manifold absolute pressure	Displays MAP
MAP	V	Manifold absolute pressure	Switch ignition ON (MAP:101 kPa {1.03 kgf/cm² , 14.6 psi}): Approx. 4.07 V Idle (after warm up) (MAP: 33 kPa {0.34 kgf/cm² , 4.8 psi}): Approx. 1.34 V Racing (engine speed is 2, 000 rpm) (MAP: 26 kPa {0.27 kgf/cm² , 3.8 psi}): Approx. 1.05 V
TP REL	%	Throttle position signal (relative value)	Accelerator pedal released: Approx. 12% Accelerator pedal depressed: Approx. 82%