Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

NO. 12 LACK/LOSS OF POWER - ACCELERATION/CRUISE [AJ] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Verify the following: Vacuum connection Air cleaner element No air leakage from intake-air system No restriction of intake-air system Proper sealing of intake manifold and components attached to intake manifold: EGR valve Fuel quality: proper octane, contamination, winter/summer blend Are all items okay?	Yes	Go to the next step.
1		No	Service as necessary. Repeat Step 1.
2	Connect WDS or equivalent to DLC-2. Tun ignition switch to ON position (Engine OFF). Retrieve any DTCs. Are there any DTCs displayed?.	Yes	DTC is displayed: Go to appropriate DTC test.
2		No	No DTC is displayed: Go to the next step.
3	Is engine overheating	Yes	Go to symptom troubleshooting "NO. 17 COOLING SYSTEM CONCERNS-OVERHEATING ".
3	Is engine overheating	No	Go to the next step.
4	Connect WDS or equivalent to DLC-2. Access APP1,APP2, RPM, MAF,TP_REL and VSS PIDs. Drive vehicle with monitoring PIDs. Are PIDs within specification? (See PCM INSPECTION .)	Yes	Go to the next step.
4		No	APP1, APP2, PIDs: Inspect if output signal from APP sensor changes smoothly. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION .) RPM PID: Inspect CKP sensor and related harness for vibration or intermittent open/short circuit, or both. (See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION .) MAF PID: Inspect for intermittent open circuit between MAF sensor and related wire harness. (See MASS AIR FLOW (MAF) SENSOR INSPECTION .) TP_REL PID: Inspect if output signal from TP sensor changes smoothly. (See THROTTLE POSITION (TP) SENSOR INSPECTION .) VSS PID: Inspect for intermittent open circuit between VSS and related wire harness. (See VEHICLE SPEEDOMETER SENSOR INSPECTION (WITHOUT ABS) .)
5	Visually inspect CKP sensor and teeth of crankshaft pulley. Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to the next step.
5		No	Replace malfunctioning part.
6	Inspect spark plug conditions. Is spark plug wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect for fuel leakage from fuel injector. Inspect ignition system for suspect cylinder. Spark plug is grayish white: Inspect for clogged fuel injector.
6		No	Install spark plugs on original cylinders. Go to the next step.
7	Remove and shake PCV valve. Does PCV valve rattle?	Yes	Go to the next step.
7	Remove and shake PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
8	Perform electronic throttle control system operation inspection. (See ELECTRONIC THROTTLE CONTROL INSPECTION .) Does electronic controlled throttle work properly?	Yes	Go to the next step.
8		No	Repair or replace malfunctioning part according to electronic throttle control system operation inspection results.
9	Inspect for restriction in the exhaust system. Is there any restriction?	Yes	Inspect exhaust system.
9		No	Go to the next step.
10	Install fuel pressure gauge between pulsation damper and fuel distributor. Short the check connector terminal F/P to body GND using a jumper wire. (See AFTER REPAIR PROCEDURE .) Turn ignition switch to ON position (Engine OFF). Inspect fuel line pressure. (See FUEL LINE PRESSURE INSPECTION .) Is fuel line pressure correct with ignition switch at ON position?	Yes	Go to the next step.
10		No	Zero or low: Inspect fuel pump relay and fuel pump circuit. Inspect for clogged fuel line. Inspect okay, replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) High: Replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
11	NOTE: The following test is for engine stall with A/C on. If other symptom exists, go to the next step. Connect pressure gauge to A/C low and high side pressure lines. Turn A/C on and measure low side and high side pressures. Are pressures within specifications? (See REFRIGERANT PRESSURE CHECK .)	Yes	Go to the next step.
11		No	If A/C is always on, go to symptom troubleshooting "NO. 24 A/C ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY ". For other symptoms, inspect following: Refrigerant charging amount Condenser fan operation
12	Inspect A/C cut-off operation. Does A/C cut-off work properly?	Yes	Go to the next step.
12		No	Inspect A/C cut-off system components.
13	Disconnect vacuum hose between purge solenoid valve and intake manifold from purge solenoid valve side. Plug opened end of vacuum hose. Drive vehicle. Does engine condition improve?	Yes	Inspect if purge solenoid valve is stuck open mechanically. Inspect EVAP control system.
13		No	Go to the next step.
14	Visually inspect CMP sensor and projections of camshaft pulley. Are CMP sensor and projections of camshaft pulley okay?	Yes	Go to the next step.
14		No	Replace malfunctioning part.
15	Inspect EGR system. Is EGR system okay?	Yes	Go to the next step.
15	Inspect EGR system. Is EGR system okay?	No	Replace malfunctioning part.
16	Perform Variable Valve Timing Control System Inspection. (See VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION INSPECTION .) Does variable valve timing control system work properly?	Yes	Go to the next step.
16		No	Repair or replace malfunctioning part according to Variable Valve Timing Control System Inspection results.
17	Is engine compression correct? (See COMPRESSION INSPECTION .)	Yes	Inspect following: Valve timing Internal transaxle components (ATX) Clutch (MTX) Brake system for dragging
17		No	Inspect for cause.
18	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, reprogram PCM if later calibration is available. Retest.