Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

NO.8 ENGINE RUNS ROUGH/ROLLING IDLE DESCRIPTION AND POSSIBLE CUSE

STEP	INSPECTION	RESULTS	ACTION
1	Does the engine knock/ping/detonate?	Yes	Go to the symptom troubleshooting "No. 13 Knocking/pinging/detonation-Acceleration/cruise". (See NO.13 KNOCKING/PINGING/DETONATION-ACCELERATION/CRUISE .)
1	Does the engine knock/ping/detonate?	No	Go to the next step.
2	Verify the following: External fuel shut off or accessory (such as kill switch, alarm.) Fuel quality (e.g. proper octane, contamination, winter/summer blend) No air leakage from intake-air system Air cleaner element (restriction, improper installation) Blockage at intake-air system (between MAF sensor and intake ports) MAF sensor installation Ignition wiring Electrical connections Fuses Smooth operation of throttle valve Are all the items normal?	Yes	Go to the next step.
2		No	Service if necessary. Repeat Step 2.
3	Connect the WDS or equivalent to the DLC-2. Turn the ignition switch to the ON position (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE .)
3		No	No DTC is displayed: Go to the next step.
4	Is the engine overheating?	Yes	Go to the symptom troubleshooting "No. 17 Cooling system concerns - Overheating". (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING .)
4	Is the engine overheating?	No	Go to the next step.
5	NOTE: The following test is for an engine running at rough idle with the A/C on. If other symptoms exist, go to the next step. Connect the pressure gauge to the A/C low and high pressure side lines.Start the engine and run it at idle.Turn the A/C switch on.Measure the low side and high side pressures.Are the pressures within the specifications?(See REFRIGERANT PRESSURE CHECK .)	Yes	Go to the next step.
5		No	If the A/C is always on, go to the symptom troubleshooting "No.24 A/C is always on or A/C compressor runs continuously". (See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY .) For other symptoms, inspect the following: Refrigerant charging amount Cooling fans operation
6	NOTE: The following test is for an engine running rough with the P/S on. If other symptoms exist, go to the next step. Connect the WDS or equivalent to the DLC-2.Turn the ignition switch to the ON position (Engine off).Retrieve any DTCs for EPS CM.Are there any DTCs displayed?	Yes	DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE .)
6		No	No DTC is displayed: Go to the next step.
7	Visually inspect the eccentric shaft position sensor and the teeth of the pulse wheel. Are the eccentric shaft position sensor and the teeth of the pulse wheel normal?	Yes	Go to the next step.
7		No	Replace the malfunctioning parts.
8	WARNING: High-voltage in ignition system can cause strong electrical shock which can result in serious injury. Avoid direct contact to the vehicle body during the rotor balance test. High-voltage spark will negatively effect the engine control. To prevent this, ground the high-tension leads and keep away from sensors and wiring harnesses. CAUTION: Rotor balance test can overheat and damage the three-way catalytic converter. Perform rotor balance test.(See ROTOR BALANCE TEST .)Is the engine speed drop value the same for each rotor?	Yes	Go to Step 13.
8		No	Go to the next step.
9	Inspect the high-tension lead for the rotor where the engine speed did not drop in Step 8 for cracks. Are there any cracks on high-tension lead?	Yes	Repair the suspected high-tension lead.
9		No	Go to the next step.
10	Is a strong blue spark visible while cranking at each disconnected high-tension lead for the rotor where the engine speed does not drop in Step 8?	Yes	Go to the next step.
10		No	Inspect for the following: Open or short circuit in ignition coil Open circuit in high-tension leads Open circuit between ignition coil connector GND terminal and GND Open circuit between ignition switch and ignition coil Open circuit between ignition coils terminal C and PCM terminal 2Z, 2AA, 2AC or 2AD
11	Inspect the spark plug for the rotor where the engine speed did not drop in Step 8. Is the spark plug wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect for fuel leakage from the injector. Spark plug is grayish white: Inspect for clogged fuel injector (FP1) (RP1).
11		No	Go to the next step.
12	Perform the drive-by-wire control system operation inspection. (See DRIVE-BY-WIRE CONTROL SYSTEM INSPECTION .) Does the drive-by-wire control system work properly?	Yes	Go to the next step.
12		No	Repair or replace the malfunctioning part according to the drive-by-wire control system operation inspection results.
13	Inspect for cracks on the high-tension leads. Are there any cracks on the high-tension leads?	Yes	Repair suspected high-tension leads.
13		No	Go to the next step.
14	Is a strong blue spark visible at each disconnected high-tension lead while cranking engine?	Yes	Go to the next step.
14		No	Inspect for the following: Open or short circuit in ignition coil Open circuit in high-tension leads Open circuit between ignition coil connector GND terminal and GND Open circuit between ignition switch and ignition coil Open circuit between ignition coils terminal C and PCM terminal 2Z, 2AA, 2AC or 2AD
15	Inspect the spark plug condition. Is the spark plug wet, covered with carbon or grayish white?	Yes	Spark plug is wet or covered with carbon: Inspect for fuel leakage from the fuel injector. Spark plug is grayish white: Inspect for clogged fuel injector (FP1) (RP1).
15		No	Install the spark plugs in the original positions. Go to the next step.
16	Perform the SSV operation inspection. (See SECONDARY SHUTTER VALVE (SSV) OPERATION INSPECTION .) Does the SSV operate properly?	Yes	Go to the next step.
16		No	Repair or replace the malfunctioning parts, according to the SSV operation inspection results.
17	NOTE: The following test is for 13B-MSP (High Power). Go to the next step for 13B-MSP (Standard Power). Perform the APV control inspection.(See AUXILIARY PORT VALVE (APV) CONTROL INSPECTION .)Does the APV control operate properly?	Yes	Go to the next step.
17		No	Repair or replace the malfunctioning parts, according to the APV control inspection results.
18	Disconnect the fuel line quick release connector and install the fuel gauge to the fuel line. Start the engine and run it at idle. Measure the fuel line pressure at idle. Is the fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION .)	Yes	Go to the next step.
18		No	Zero or low: Inspect for clogged fuel line. If normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
19	Visually inspect for fuel leakage at the fuel injector, O-ring, and fuel line. Service if necessary. Does the fuel line pressure hold after the ignition switch is turned off? (See FUEL LINE PRESSURE INSPECTION .)	Yes	Go to the next step.
19		No	Inspect the fuel injector. (See FUEL INJECTOR INSPECTION .) If the fuel injector is normal, replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
20	Access the ECT PID. Does the ECT PID indicate the proper engine coolant temperature? (See PCM INSPECTION .)	Yes	Go to the next step.
20		No	Inspect for the following: ECT sensor Open or short circuit between ECT sensor and PCM terminal 2K or 1U
21	Connect the WDS or equivalent to the DLC-2. Start the engine and run it at idle. Access the LONG FT1 PID. Measure the LONG FT1 PID at idle. Is the PID value between -14% and +14% ?	Yes	Go to the next step.
21		No	The LONG FT1 PID is out of the specification. LONG FT1 PID less than -14% (too rich): Inspect the EVAP control system. If the system is normal, go to Step 27. LONG FT1 PID more than +14% (too lean): Inspect for air leakage at intake-air system components. If the system is normal, go to the next step.
22	Visually inspect the exhaust system part. Is there any deformed exhaust system part?	Yes	Repair or replace the suspected part.
22		No	Go to the next step.
23	Perform the metering oil pump control inspection. (See METERING OIL PUMP CONTROL INSPECTION .) Does the metering oil pump control operate properly?	Yes	Go to the next step.
23		No	Repair or replace the malfunctioning part according to the inspection results.
24	Perform the fuel injector (FP1) (RP1) operation inspection. (See FUEL INJECTOR OPERATION INSPECTION .) Are the fuel injectors (FP1) (RP1) operating properly?	Yes	Go to the next step.
24		No	Repair or replace the malfunctioning parts, according to the fuel injector (FP1) (RP1) operation inspection results.
25	Inspect the fuel injectors (FP1) (RP1) for the following: (See FUEL INJECTOR INSPECTION .) Leakage Clogging Injector amount Are the fuel injectors (FP1) (RP1) normal?	Yes	Go to the next step.
25		No	Replace the fuel injector (FP1) (RP1). (See FUEL INJECTOR REMOVAL/INSTALLATION .)
26	Perform the AIR inspection. (See SECONDARY AIR INJECTION (AIR) SYSTEM INSPECTION .) Does the AIR system operate properly?	Yes	Go to the next step.
26		No	Repair or replace the malfunctioning parts, according to the inspection results.
27	Inspect the engine compression. (See COMPRESSION INSPECTION .) Is it normal?	Yes	Go to Step 33.
27		No	Go to the next step.
28	Perform the metering oil pump control inspection. (See METERING OIL PUMP CONTROL INSPECTION .) Does the metering oil pump control operate properly?	Yes	Go to the next step.
28		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
29	Check the engine oil condition. Is the engine oil low viscosity and/or is there a gasoline odor?	Yes	Replace the engine oil. Inspect the ECT sensor and the related wiring harnesses. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION .) After that overhaul or replace the engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
29		No	Go to the next step.
30	Inspect the oil pressure. (See OIL PRESSURE INSPECTION .) Is the oil pressure within the specification?	Yes	Go to the next step.
30		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
31	Turn the ignition switch off. Disconnect the fuel line quick release connector and install the fuel gauge to the fuel line. Start the engine and run it at idle. Measure the fuel line pressure at idle. Is the fuel line pressure correct at idle? (See FUEL LINE PRESSURE INSPECTION .)	Yes	Go to the next step.
31		No	Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) After that overhaul or replace the engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
32	Check the oil pipe between the metering oil pump and the metering oil nozzle. Is there any air and/or clogging in oil pipe?	Yes	Inspect and repair for leakage and/or clogging in the oil passage at engine. After that overhaul or replace engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
32		No	Overhaul or replace the engine. (See ENGINE REMOVAL/INSTALLATION or OVERHAUL - 1.3L (13B-MSB) .)
33	Disconnect the vacuum hose between the purge solenoid valve and the intake manifold at the quick release connector. Plug the opening end of vacuum hose. Start the engine. Does the engine condition improve?	Yes	Check if the purge solenoid valve sticks open mechanically. Inspect the EVAP control system.
33		No	Inspect for the following: Jet air mixing system (clogged or leakage) Primary intake port (deposited carbon or foreign materials) Eccentric shaft position sensor pulse wheel (damaged, improper installation)
34	Verify test results. If normal, return to the diagnostic index to service any additional symptoms. If malfunction remains, inspect the related Service Bulletins and/or the On-line Repair Information and perform the repair or diagnosis.

*: 13B-MSP (High Power)