Diagnostic procedure

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

HARD START/LONG CRANK/ERRATIC START/ERRATIC CRANK - DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Inspect for following: Vacuum leakage Proper fuel quality (e.g. proper octane, contamination, winter/summer blend) Loose bands on intake-air system Cracks on intake-air system parts Air cleaner restriction 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. 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	Is engine overheating?	Yes	Go to flowchart in NO.17 COOLING SYSTEM CONCERNS-OVERHEATING .
3	Is engine overheating?	No	Go to next step.
4	Inspect ignition coil related harnesses condition (intermittent open or short circuit) for all cylinders. Are all harnesses condition okay?	Yes	Go to next step.
4		No	Repair suspected wiring harness.
5	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. Spark plug is grayish white: Inspect for clogged fuel injector.
5		No	Install spark plugs on original cylinders. Go to next step.
6	Visually inspect CKP sensor and teeth of crankshaft pulley. Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to next step.
6		No	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	Install fuel pressure gauge between pulsation clamper and fuel distributor. Connect jumper wire between F/P terminal at DLC in engine compartment and GND. (See AFTER REPAIR PROCEDURE .) Turn ignition key to ON (Engine OFF). Is fuel line pressure correct? Fuel line pressure 420-460 kPa {4.3-4.6 kgf/cm2, 61-66 psi}	Yes	Go to next step.
8		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.
9	Is fuel line pressure held after ignition key is turned to OFF?	Yes	Go to next step.
9		No	Inspect pressure regulator diaphragm condition. If condition is okay, inspect fuel injector. If condition is not okay, replace pressure regulator.
10	Disconnect vacuum hose from pressure regulator and plug hose. Start engine. Does fuel line pressure remain within 0 kPa {0.21 kgf/cm2,3.0 psi} while driving vehicle?	Yes	Go to next step.
10		No	Inspect for clogged fuel filter.
11	Connect vacuum hose to pressure regulator. Install vacuum gauge to intake manifold. Start engine. Does fuel pressure gauge reading increase as vacuum gauge reading decreases and/or fuel pressure gauge reading decrease as vacuum gauge reading increases?	Yes	Go to next step.
11		No	Connect vacuum pump to pressure regulator. Start engine. Inspect if fuel pressure gauge reading changes as vacuum changes. If it changes, inspect vacuum line. If it does not change, replace pressure regulator.
12	Disconnect vacuum hose from purge solenoid valve and plug opening end of vacuum hose. Attempt to start engine. Is starting condition improved?	Yes	Inspect if purge solenoid valve sticks open.
12		No	Go to next step.
13	Inspect MAF sensor for contamination. Is there any contamination?	Yes	Replace MAF sensor.
13		No	Go to next step.
14	Inspect for restriction in the exhaust system. Is there any restriction?	Yes	Inspect exhaust system.
14		No	Go to next step.
15	Inspect engine condition while tapping EGR valve housing. Does engine condition improve?	Yes	Replace EGR valve.
15		No	Go to next step.
16	Inspect starting system. (See STARTER INSPECTION .) Is starting system normal?	Yes	Inspect for loose connectors or poor terminal contact. If okay, remove EGR valve and visually inspect for mechanically stuck EGR valve.
16		No	Repair or replace components as required.
17	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.