Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

NO.12 LACK/LOSS OF POWER-ACCELERATION/CRUISE [BP, BP WITH TC] DIAGNOSTIC PROCEDURE

TEP	INSPECTION		ACTION
1	Verify following: Vacuum connection ACL 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, IAC valve) Fuel quality: Proper octane, contamination, winter/summer blend Are all items okay?	Yes	Go to the next step.
1		No	Service if necessary and repeat Step 1.
2	Connect WDS or equivalent to DLC-2. Turn ignition switch to ON. Retrieve any DTC. Is "PASSED" displayed?	Yes	No DTC displayed: Go to the next step.
2		No	DTC displayed: Go to appropriate DTC test.
3	Is engine overheating?	Yes	Go to symptom troubleshooting No.17 "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 RPM, MAF, TP and VSS PIDs. Drive vehicle while monitoring PIDs. Are PIDs within specifications? (See PCM INSPECTION )	Yes	Go to the next step.
4		No	RPM PID: Inspect CKP sensor and related harness for vibration and/or intermittent open/short circuit. MAF PID: Inspect for intermittent open circuit of MAF sensor and related wiring harness. TP PID: Inspect if TP sensor output increases smoothly. VSS PID: Inspect for intermittent open circuit of VSS and related wiring harness.
5	Inspect variable valve timing operation. Is variable valve timing operation okay?	Yes	Go to the next step.
5		No	Repair of replace malfunctioning parts.
6	Visually inspect CKP sensor and teeth of crankshaft pulley. Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to the next step.
6		No	Replace malfunctioning parts.
7	Measure gap between CKP sensor and teeth of crankshaft pulley. Specification 0.5-1.5 mm {0.020-0.059 in} Is the gap within specification?	Yes	Go to the next step.
7		No	Adjust CKP sensor.
8	Inspect spark plug conditions. Is spark plug wet, grayish white, or covered with carbon?	Yes	Spark plug is wet or covered with carbon: inspect for fuel leakage from fuel injector. Spark plug is grayish white: Inspect for clogged fuel injector.
8		No	Install spark plugs on original cylinders. Go to the next step.
9	Remove and shake PCV valve. Does PCV valve rattle?	Yes	Go to the next step.
9	Remove and shake PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
10	Is there any restriction in exhaust system?	Yes	Inspect exhaust system.
10	Is there any restriction in exhaust system?	No	Go to the next step.
11	Install fuel gauge between fuel filter and fuel distributor. Connect a jumper wire between terminal F/P at DLC in engine compartment and ground. Turn ignition switch to ON. Is fuel line pressure correct with ignition switch at ON? Fuel line pressure 370-420 kPa {3.7-4.3 kgf/cm2, 53-61 psi}	Yes	Go to the next step.
11		No	Zero or low: Inspect FP circuit Inspect for open FP relief valve Inspect for fuel leakage inside pressure regulator Inspect for clogged main fuel line Inspect pulsation damper High: Inspect pressure regulator for high pressure cause Inspect for clogged fuel return line
12	NOTE: Following test is for engine stalling with A/C on concern. If other symptoms exist, 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 the pressures within specifications? (See REFRIGERANT PRESSURE CHECK )	Yes	Go to the next step.
12		No	If A/C is always on, go to symptom troubleshooting No.24 "A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY ". For other symptoms, inspect following: Refrigerant charging amount Condenser fan operation
13	Inspect for A/C cut-off operation. Does A/C cut-off work properly?	Yes	Go to the next step.
13		No	Inspect A/C cut-off system components.
14	Disconnect vacuum hose between purge solenoid valve and intake manifold from purge solenoid valve side. Plug opening end of vacuum hose. Drive vehicle. Does engine condition improve?	Yes	Inspect if purge solenoid valve is stuck open mechanically. Inspect EVAP control system.
14		No	Go to the next step.
15	Verify VTCS operation. (See VARIABLE TUMBLE CONTROL SYSTEM (VTCS) OPERATION INSPECTION ) Is VTCS operation okay?	Yes	Go to the next step.
15		No	Repair or replace malfunctioning parts.
16	Visually inspect CMP sensor and teeth of camshaft pulley. Are CMP sensor and teeth of camshaft okay?	Yes	Go to the next step.
16		No	Replace malfunctioning parts.
17	Inspect EGR system. Is EGR system okay?	Yes	Go to the next step.
17	Inspect EGR system. Is EGR system okay?	No	Replace malfunctioning parts.
18	Is engine compression correct?	Yes	Inspect following: Valve timing Internal transmission components (AT only) Clutch (MT only) Brake system for dragging
18	Is engine compression correct?	No	Inspect for cause.
19	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 PCM.