Poor Fuel Economy

POOR FUEL ECONOMY DESCRIPTION

11	POOR FUEL ECONOMY
DESCRIPTION	FUEL ECONOMY UNSATISFACTORY

POOR FUEL ECONOMY INSPECTION/ACTION 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. Perform 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 next step.
1		No	Service as required. Verify symptom no longer exists.
2	PERFORM 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 DIAGNOSTIC TROUBLE CODE NUMBERS .
2		No	Go to next step.
3	CHECK PIDS Connect WDS or equivalent tester. Check following PIDS. DPFE, ECT, IAC, LONGFT1, LONGFT2, VPWR. See PCM QUICK TEST . Are PIDS within specification?	Yes	Go to next step.
3		No	Service 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 next step. If not OK, clean or replace spark plugs. See IGNITION COIL-ON-PLUG AND SPARK PLUG -- 2.3L , or IGNITION COIL-ON-PLUG AND SPARK PLUG -- 3.0L (4V) .
4		No	Check following: High-tension leads. See TEST 15: IGNITION SCOPE TEST . CKP sensor. See CRANKSHAFT POSITION (CKP) SENSOR MALFUNCTION . CMP sensor. See CAMSHAFT POSITION SENSOR (CMP) MALFUNCTION .
5	CHECK FUEL DELIVERY SYSTEM Perform fuel pressure inspection. See TEST 9: FUEL LINE/FUEL PRESSURE HOLD INSPECTION . Fuel line pressure: 240-380 kPa (35-55 psi). Is fuel pressure correct?	Yes	Go to next step.
5		No	If pressure is greater than 380 kPa (55 psi): Replace fuel pump. See FUEL PUMP MODULE . 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 10: FUEL INJECTOR INSPECTION . If injector leaks, service as necessary. See FUEL INJECTORS . If injector OK, go to next step.
6		No	Check fuel supply line for restriction.
7	CHECK EXHAUST SYSTEM Is there a restriction in the exhaust system?	Yes	Service as required.
7		No	Go to next step.
8	CHECK AUTOMATIC TRANSAXLE (A/T) If vehicle has manual transaxle, go to next step. If vehicle has automatic transaxle, go to TROUBLESHOOTING for Diagnostic Strategy. Is automatic transaxle OK?	Yes	Go to next step.
8		No	Service as required.
9	CHECK PCV SYSTEM Remove PCV valve and shake it. Does PCV valve rattle?	Yes	Install PCV valve. Go to next step.
9		No	Replace PCV valve. See POSITIVE CRANKCASE VENTILATION (PCV) VALVE -- 2.3L .
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 one minute. Does vacuum hold paper in place?	Yes	Go to next step.
10		No	Disconnect evaporative hose. Place a stiff piece of paper over the hose. Wait one minute. Does vacuum hold paper in place? If yes, See EVAPORATIVE EMISSION (EVAP) SYSTEM MALFUNCTION . If no, check for vacuum leaks, obstructions in the PCV system, oil cap, PCV valve, rocker cover bolt torque/gasket leak. Service 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	Go to next step.
11		No	Repair as necessary. Verify a symptom no longer exists.
12	Verify test results. If OK, see DIAGNOSTIC INDEX to service any additional symptoms.