Diagnostic procedure

POOR FUEL ECONOMY - DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Inspect following: Air cleaner element for contamination ATF level Fuel quality Coolant level Are all items okay?	Yes	Go to next step.
1		No	Service as necessary. Repeat Step 1.
2	Connect WDS or equivalent to DLC-2. Turn ignition key to ON (Engine OFF). Retrieve any DTCs. Is "PASSED" displayed?	Yes	No DTC is displayed: Go to next step.
2		No	DTC is displayed: Go to appropriate DTC test.
3	Access ECT PID. Drive vehicle while monitoring PID. (See PCM INSPECTION USING THE SST (WDS OR EQUIVALENT) ) Is PID within specification?	Yes	Go to next step.
3		No	Inspect for coolant leakage. Inspect cooling fan operations or thermostat operations.
4	Perform spark test. (See SPARK TEST .) Is strong blue spark visible at each cylinder?	Yes	Inspect for following: Spark plugs malfunction CMP sensor is installed improperly. Trigger wheel damage on camshaft Open or short circuit on CMP sensor Open or short circuit between CMP sensor and PCM terminal 2 or 28 Repair or replace malfunctioning part. If okay, go to next step.
4		No	Repair or replace malfunctioning part according to spark test results.
5	Install fuel pressure gauge between fuel filter and fuel distributor. Start engine and run it at idle. Measure fuel line pressure at idle. Is fuel line pressure correct at idle? Fuel line pressure 420-460 kPa {4.3-4.6 kgf/cm2, 61-66 psi}	Yes	Go to next step.
5		No	Zero or low: Inspect fuel pump circuit. Inspect for open fuel pump relief valve. Inspect for fuel leakage inside pressure regulator. Inspect for clogged main fuel line. High: Inspect pressure regulator for high pressure cause. Inspect for clogged fuel return line.
6	Inspect IMCC operation (See INTAKE MANIFOLD COMMUNICATION CONTROL (IMCC) ACTUATOR INSPECTION ) Does IMCC work properly?	Yes	Go to next step.
6		No	Repair or replace malfunctioning part.
7	Remove and shake PCV valve. Does PCV valve rattle?	Yes	Go to next step.
7	Remove and shake PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
8	Inspect for restriction in the exhaust system. Is there any restriction?	Yes	Inspect exhaust system.
8		No	Go to next step.
9	Is brake system functioning properly?	Yes	Go to next step.
9	Is brake system functioning properly?	No	Inspect for cause.
10	Inspect MAF sensor for contamination. Is there any contamination?	Yes	Replace MAF sensor.
10		No	Go to next step.
11	Is engine compression correct?	Yes	Inspect valve timing.
11	Is engine compression correct?	No	Inspect for cause.
12	Verify test results. If okay, return to diagnostic index to service any additional symptoms. If malfunction remains, inspect related Service Bulletins and/or On-line Repair 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 or reprogram PCM.