Engine Runs Rough/Rolling Idle (Us): Notes

ENGINE RUNS ROUGH/ROLLING IDLE (SKYACTIV-G, US) DESCRIPTION AND POSSIBLE CAUSE

Troubleshooting item	Engine runs rough/rolling idle
Description	Idle speed lower than the specification. Idling speed unstable, increases/decreases.
Possible cause	Engine overheating PCM DTC is stored Erratic signal to PCM APP sensor or related circuit malfunction ECT sensor No. 1 or related circuit malfunction ECT sensor No. 2 or related circuit malfunction MAF sensor or related circuit malfunction MAP sensor or related circuit malfunction A/F sensor or related circuit malfunction HO2S or related circuit malfunction Improper load signal input Improper A/C request signal Improper operation of A/C system Improper operation of drive-by-wire control system Incorrect fuel injection timing Fuel injector malfunction Purge solenoid valve malfunction Poor fuel quality Air leakage from intake-air system Intake-air system restriction Electrical connector disconnected Fuel leakage Vacuum leakage Improper engine oil viscosity Erratic signal from CKP sensor Loose installation Damaged trigger wheel (crankshaft pulley) Open or short circuit in related wiring harness Erratic or no signal from CMP sensor Loose installation Damaged trigger wheel (intake camshaft and/or exhaust camshaft) Open or short circuit in related wiring harness Inadequate fuel pressure (high or low pressure side) Fuel pressure sensor or related circuit malfunction High pressure fuel pump malfunction Spill valve control solenoid valve control circuit malfunction (damage to driver in PCM caused by short circuit to ground system) Spill valve control solenoid valve malfunction (built-into high pressure fuel pump) Relief valve (built-into high pressure fuel pump) malfunction Fuel line restriction Fuel filter clogged Fuel pump unit malfunction Improper operation of electric variable valve timing control system (PCM DTC is stored.) Improper operation of hydraulic variable valve timing control system Low engine compression Improper intake valve timing Improper exhaust valve timing Spark plug malfunction Ignition coil malfunction Exhaust system and/or TWC restriction PCV valve malfunction Injector driver (built-into PCM) malfunction
Possible cause	WARNING: The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services: Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Highly pressurized fuel may spray out if the fuel line is cut. Due to the following dangers occurring with a fuel spray, always complete the "Fuel Line Safety Procedure" to prevent the fuel from spraying. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G (VIN M (US))] .) (See BEFORE SERVICE PRECAUTION [SKYACTIV-G (WITHOUT CYLINDER Fuel may cause irritation if it comes in contact with skin and eyes. If fuel ignites and causes a fire, it may lead to serious injury or death, and damage to property and facilities. Fuel is highly flammable and dangerous. Fuel line spills and leakage can cause serious injury or death, and damage to equipment. Always refer to the "Quick Release Connector Removal/Installation (fuel system)" before performing the fuel hose installation, and execute the "Fuel Leakage Inspection" after installation. (See QUICK RELEASE CONNECTOR (FUEL SYSTEM) REMOVAL/INSTALLATION [SKYACTIV-G (VIN M (US))] .) (See QUICK RELEASE CONNECTOR (FUEL SYSTEM) REMOVAL/INSTALLATION [SKYACTIV-G (VIN L (US))] .) (See AFTER SERVICE PRECAUTION [SKYACTIV-G (VIN M (US))] .) (See AFTER SERVICE PRECAUTION [SKYACTIV-G (VIN L (US))] .) CAUTION: Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.
Courtesy of MAZDA MOTORS CORP.

CAUTION:

Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.