Poor Fuel Economy

POOR FUEL ECONOMY REFERENCE CHART

11	POOR FUEL ECONOMY
DESCRIPTION	FUEL ECONOMY UNSATISFACTORY

DTC DETECTION CONDITION POSSIBLE COUSES CHART

STEP	INSPECTION		ACTION
1	PRELIMINARY CHECKS NOTE: Since driving habits can have a significant influence on fuel economy, verify concern before starting an in-depth diagnosis. Also, the following external factors could contribute to "poor fuel economy" conditions: Stop/go city driving. Improper tire pressure/size. Vehicle loads, trailer towing, etc.. Extended winter warm-up conditions. High speed driving. Improper axle ratio. Improper speedometer gear ratio. Road/weather conditions. Aftermarket add-ons. Short-run operations. Customer expectations/driving habits. Carry out the following preliminary checks: Air cleaner tube blockage. Contaminated air cleaner element. Transaxle fluid level. Fuel quality. Coolant level. Are all checks OK?	Yes	GO to the next step.
1		No	REPAIR as required. VERIFY symptom no longer exists.
2	CARRY OUT PCM QUICK TEST See PCM QUICK TEST . Are any DTCs displayed during Continuous Memory Self-Tests, Key ON, Engine OFF (KOEO), Engine OFF (KOEO) or Key ON, Engine OFF (KOEO), Engine Running (KOER)?	Yes	CHECK for cause. See DTC INDEX - PCM .
2		No	GO to the next step.
3	CHECK PIDs Connect IDS or equivalent tester. Check following PIDs. ECT, LONGFT1, LONGFT2, VPWR. See PCM QUICK TEST . Are PIDs within specification?	Yes	GO to the next step.
3		No	REPAIR as required.
4	CHECK SECONDARY IGNITION SYSTEM Is strong blue spark visible at each disconnected high-tension lead while cranking engine?	Yes	CHECK spark plugs. If OK, GO to the next step. If not OK, CLEAN or INSTALL new spark plugs. See SPARK PLUGS REMOVAL/INSTALLATION - 2.5L or SPARK PLUGS REMOVAL/INSTALLATION - 3.0L .
4		No	CHECK following: High-tension leads. See TEST 11: IGNITION SCOPE TEST . CKP sensor. See CRANKSHAFT POSITION (CKP) SENSOR MALFUNCTION . CMP sensor. See CAMSHAFT POSITION (CMP) SENSOR MALFUNCTION .
5	CHECK FUEL DELIVERY SYSTEM Carry out fuel pressure inspection. See TEST 8: FUEL LINE/FUEL PRESSURE HOLD INSPECTION . Fuel line pressure: 240-380 kPa (35-55 psi). Is fuel pressure correct?	Yes	GO to the next step.
5		No	If pressure is greater than 380 kPa (55 psi): INSTALL a new fuel pump. See FUEL PUMP MODULE REMOVAL/INSTALLATION . If pressure is less than 240 kPa (35 psi): CHECK fuel supply line for restriction.
6	CHECK FUEL DELIVERY SYSTEM Check fuel pump fuel flow. See TEST 4: FUEL DELIVERY SYSTEM . Did fuel system flow the required amount of fuel?	Yes	CHECK injector for leakage. See TEST 9: FUEL INJECTOR INSPECTION . If injector leaks, REPAIR as necessary. See FUEL RAIL REMOVAL/INSTALLATION - 2.5L or FUEL RAIL REMOVAL/INSTALLATION - 3.0L 01-14A-29. If injector OK, GO to the next step.
6		No	CHECK fuel supply line for restriction.
7	CHECK EXHAUST SYSTEM Is there a restriction in the exhaust system?	Yes	REPAIR as required.
7		No	GO to the next step.
8	CHECK AUTOMATIC TRANSAXLE (A/T) If vehicle has manual transaxle, go to the next step. If vehicle has automatic transaxle, go to AUTOMATIC TRANSAXLE - 2.5L & 3.0L for Diagnostic Strategy. Is automatic transaxle OK?	Yes	For 2.5L engine, GO to the next step. For 3.0L engine, GO to step 10.
8		No	REPAIR as required.
9	CHECK PCV SYSTEM Remove PCV valve and shake it. Does PCV valve rattle?	Yes	REINSTALL PCV valve. GO to the next step.
9		No	INSTALL a new PCV valve.
10	CHECK PCV SYSTEM Start engine and bring to normal operating temperature. Disconnect crankcase ventilation hose from throttle body. Place a stiff piece of paper over the hose. Wait 1 minute. Does vacuum hold paper in place?	Yes	GO to the next step.
10		No	DISCONNECT evaporative hose. PLACE a stiff piece of paper over the hose. WAIT 1 minute. Does vacuum hold paper in place? If yes, see EVAPORATIVE EMISSION (EVAP) MONITOR AND SYSTEM MALFUNCTION . If no, CHECK for vacuum leaks, obstructions in the PCV system, oil cap, PCV valve, rocker cover bolt torque/gasket leak. REPAIR as required.
11	ADDITIONAL CHECKS Additional checks: Brake drag. Base engine concerns. Incorrect PCV valve. Contaminated MAF/IAT sensor. Cooling system. Are all checks OK?	Yes	Verify test results. If OK, See DIAGNOSTIC INDEX to REPAIR any additional symptoms.
11		No	REPAIR as necessary. VERIFY a symptom no longer exists.