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.4 HARD START/LONG CRANK/ERRATIC START/ERRATIC CRANK [BP, BP WITH TC] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	NOTE: The following test should be performed on vehicles with immobilizer system. Go to Step 12 for vehicles without immobilizer system. Connect WDS or equivalent to DLC-2. Do following conditions appear? Engine dose not start completely. DTC P1624 is displayed.	Yes	Both conditions appear: Go to Step 4.
1		No	Either or other condition appears: Go to the next step.
2	Does engine stall after approx.2 s since engine is started?	Yes	Go to the next step.
2	Does engine stall after approx.2 s since engine is started?	No	Immobilizer system is okay. Go to Step 12.
3	Is immobilizer control module connector securely connected to immobilizer control module?	Yes	Go to the next step.
3		No	Connect immobilizer control module connector securely. Return to Step 2.
4	Does immobilizer indicator light flash and indicate any of following immobilizer system DTCs? DTC: 01, 02, 03,11,21	Yes	Go to "ON-BOARD DIAGNOSTIC FUNCTION " of immobilizer system
4		No	Go to the next step.
5	Does immobilizer indicator light illuminate?	Yes	Go to step 8.
5	Does immobilizer indicator light illuminate?	No	Go to the next step.
6	Does immobilizer indicator light flash and indicate any of following immobilizer system DTCs more than 135 s after ignition switch is turned to ON? DTC: 24, 30	Yes	Go to "ON-BOARD DIAGNOSTIC FUNCTION " of immobilizer system
6		No	Install spark plugs on original cylinders. Go to the next step.
7	Turn ignition switch to OFF. Disconnect immobilizer control module connector. Connect jumper wire between immobilizer control module connector terminal M and GND. Turn ignition switch to ON. Does immobilizer indicator light illuminate?	Yes	Reconnect immobilizer control module connector. Go to the next step.
7		No	Inspect for open circuit between immobilizer control module connector terminal M and instrument cluster. If okay, inspect immobilizer indicator light bulb. Repair or replace if necessary. Reconnect immobilizer control module connector, then return to Step 4.
8	Connect WDS or equivalent to DLC-2 and retrieve DTC. Is any of following DTCs displayed? DTC: P1602, P1603, P1604, P1621, P1622, P1624	Yes	Go to appropriate DTC test.
8		No	Go to the next step.
9	Is there continuity between PCM GND terminals 3A / 3B and GND?	Yes	Go to the next step.
9		No	Repair or replace wiring harness.
10	Turn ignition switch to ON. Measure PCM terminal 4AF. Is PCM terminal 4AF voltage okay? PCM terminal 4AF voltage: Battery voltage	Yes	Go to the next step.
10		No	Repair or replace wiring harness.
11	Disconnect immobilizer control module connector. Turn ignition switch on. Is there battery voltage at immobilizer control module connector terminal J?	Yes	Inspect for open circuit between PCM connector terminal 3S and immobilizer control module connector terminal A.
11		No	Repair or replace wiring harness between immobilizer control module connector terminal J and fuse panel.
12	Verify following: Vacuum leakage Fuel quality (i.e proper octane, contamination, winter/summer blend) Loose bands on intake-air system Cracks on intake-air system parts ACL restriction Are all items okay?	Yes	Go to the next step.
12		No	Service if necessary. Repeat step 12.
13	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.
13		No	DTC displayed: Go to appropriate DTC test.
14	Is engine overheating?	Yes	Go to flowchart 17 for "NO.17 COOLING SYSTEM CONCERNS-OVERHEATING "
14	Is engine overheating?	No	Go to the next step.
15	Inspect for cracks on high-tension leads. Is there any crack on high-tension leads?	Yes	Repair suspected high-tension lead.
15		No	Go to the next step.
16	Inspect variable valve timing operation. Is variable valve timing operation okay?	Yes	Go to the next step.
16		No	Repair or replace malfunctioning parts.
17	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.
17		No	Install spark plugs on original cylinders. Go to the next step.
18	Visually inspect CKP sensor and teeth of crankshaft pulley. Are CKP sensor and teeth of crankshaft pulley okay?	Yes	Go to the next step.
18		No	Replace malfunctioning parts.
19	Measure gap between CKP sensor and teeth of crankshaft pulley. Specification 0.5-1.5 mm {0.020-0.59 in} Is gap within specification?	Yes	Go to the next step.
19		No	Adjust CKP sensor.
20	Remove and inspect PCV valve. Does PCV valve rattle?	Yes	Go to the next step.
20	Remove and inspect PCV valve. Does PCV valve rattle?	No	Replace PCV valve.
21	Install fuel gauge between fuel filter and fuel distributor. Connect a jumper wire between terminal F/P at DLC in engine compartment and GND. (See AFTER SERVICE PRECAUTION ) Turn ignition switch to ON. Is fuel line pressure correct? Fuel line pressure 370-420 kPa {3.7-4.3 kgf/cm2, 53-61 psi}	Yes	Go to the next step.
21		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
22	Is fuel line pressure fluctuation within specification after ignition switch is turned off? Fuel pressure fluctuation 370-420 kPa {3.7-4.3 kgf/cm2, 53-61 psi}	Yes	Go to the next step.
22		No	Inspect pressure regulator diaphragm condition. If condition is okay, inspect fuel injector. If condition is not okay, replace pressure regulator.
23	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 is stuck open.
23		No	Go to the next step.
24	Inspect MAF sensor for contamination. Is there any contamination?	Yes	Replace MAF sensor.
24		No	Go to the next step.
25	Is there restriction in exhaust system?	Yes	Inspect exhaust system.
25	Is there restriction in exhaust system?	No	Go to the next step.
26	Inspect engine condition while tapping EGR valve housing. Does engine condition improve?	Yes	Replace EGR valve.
26		No	Go to the next step.
27	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.
27		No	Inspect continuity of stepping motor coil.
28	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.