NO.8 ENGINE RUNS ROUGH/ROLLING IDLE [MZR-CD (RF Turbo)]


8	ENGINE RUNS ROUGH/ROLLING IDLE
DESCRIPTION	• Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively. • Idle speed is too slow and engine shakes excessively.
POSSIBLE CAUSE	• Poor fuel quality • Air leakage from intake-air system • Intake-air system restriction • Incorrect idle speed • Engine overheating • A/C system improper operation • EGR system improper operation • EGR water cooler malfunction • Glow system malfunction • Fuel leakage • Inadequate fuel pressure • Fuel pressure sensor or related circuit malfunction • Suction control valve malfunction (built-in supply pump) • Fuel pressure limiter malfunction (built-in common rail) • Fuel filter clogging • Fuel line restriction • Incorrect fuel injection timing • Erratic signal from CKP sensor • Erratic signal from CMP sensor • ECT sensor or related circuit malfunction • Boost sensor or related circuit malfunction • Idle switch misadjustment • Idle switch or related circuit malfunction • Accelerator pedal position sensor misadjustment • Accelerator pedal position sensor or related circuit malfunction • MAF/IAT sensor malfunction • Neutral switch or related circuit malfunction • Supply pump malfunction • Fuel injector malfunction • Low engine compression • Improper valve timing • Engine compression excessive unbalance for each cylinder • Unbalanced fuel injection amount for each cylinder • IDM or related circuit malfunction 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. • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual. (See BEFORE SERVICE PRECAUTION [MZR-CD (RF Turbo)].) (See AFTER SERVICE PRECAUTION [MZR-CD (RF Turbo)].)


STEP	INSPECTION	RESULTS	ACTION
1	Inspect for the following: • Fuel quality (e.g.: including water contamination, winter/summer blend) • Fuel line/fuel filter clogging • Loose bands on intake-air system • Cracks on intake-air system parts • Intake-air system restriction • Vacuum leakage Are all items normal?	Yes	Go to the next step.
1		No	Service if necessary Repeat Step 1.
2	Is the engine overheating?	Yes	Go to symptom troubleshooting "NO.17 COOLING SYSTEM CONCERNS-OVERHEATING." (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR-CD (RF Turbo)].)
2	Is the engine overheating?	No	Go to the next step.
3	Connect the WDS or equivalent to the DLC-2. Turn the engine switch to the ON position. Retrieve any DTC. Is DTC displayed?	Yes	DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD (RF Turbo)].) Communication error message is displayed: Inspect for the following: • Open circuit between PCM control relay and PCM terminal 53 or 79 • Open circuit PCM control relay and PCM terminal 69 • PCM control relay stuck open • Open or poor GND circuit (PCM terminal 65, 85, 103 or 104) • Poor connection vehicle body GND
3		No	No DTC is displayed: Go to the next step.
4	Does the engine run normal after warm up?	Yes	Inspect the glow system operation. (See RELAY INSPECTION.) Replace the malfunctioning part if necessary. If the glow system is normal, go to the next step.
4	Does the engine run normal after warm up?	No	Go to the next step.
5	Note • The the following test should be performed on the vehicles with the A/C system. If the following test cannot be performed due to the engine stalling, go to the next step. • Go to the next step for the vehicle without the A/C system. Connect pressure gauge to A/C line. Turn the blower and the A/C switches on. Is pressure within the specifications?	Yes	Go to the next step.
5		No	A/C is always on: Go to symptom troubleshooting "NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY". (See NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF Turbo)].) Other symptoms: Inspect for the following: • Refrigerant charging amount • Cooling fan and/or condenser fan operation
6	Depress the accelerator pedal slightly. Crank the engine. Does the engine start now?	Yes	Inspect idle speed. (See IDLE SPEED INSPECTION [MZR-CD (RF Turbo)].)
6		No	Go to the next step.
7	Inspect the adjustment of the accelerator pedal position sensor and the idle switch. (See ACCELERATOR PEDAL POSITION (APP) SENSOR ADJUSTMENT [MZR-CD (RF Turbo)].) (See IDLE SWITCH INSPECTION [MZR-CD (RF Turbo)].) Are the accelerator pedal position sensor and the idle switch adjusted correctly?	Yes	Go to the next step.
7		No	Adjust the accelerator pedal position sensor and the idle switch correctly. (See ACCELERATOR PEDAL POSITION (APP) SENSOR ADJUSTMENT [MZR-CD (RF Turbo)].) (See IDLE SWITCH ADJUSTMENT [MZR-CD (RF Turbo)].)
8	Inspect for fuel leakage from the fuel pipe. Is any fuel leakage found on the fuel pipe?	Yes	Repair or replace if necessary.
8		No	Go to the next step.
9	Visually inspect the CKP sensor and teeth of the pulse wheel. Are the CKP sensor and teeth of the pulse wheel normal?	Yes	Go to the next step.
9		No	Replace the malfunctioning parts.
10	Measure the gap between the CKP sensor and teeth of the pulse wheel. Specification 1.5-2.5 mm {0.059-0.098 in} Is the gap within the specification?	Yes	Go to the next step.
10		No	Adjust the CKP sensor position.
11	Visually inspect the CMP sensor and teeth of the pulse wheel. Are the CMP sensor and teeth of the pulse wheel normal?	Yes	Inspect the following PIDs: (See PCM INSPECTION [MZR-CD (RF Turbo)].) • ECT • IAT • MAF • MAP • RPM If PID value is not as specified, repair or replace the malfunctioning part. If PID value is normal, go to the next step.
11		No	Replace malfunctioning parts.
12	Inspect the fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [MZR-CD (RF Turbo)].) Is the fuel pressure normal?	Yes	Go to the next step.
12		No	Replace the common rail.
13	Inspect the suction control valve. (See SUCTION CONTROL VALVE INSPECTION [MZR-CD (RF Turbo)].) Is the suction control valve normal?	Yes	Go to the next step.
13		No	Repair the supply pump. (See SUPPLY PUMP INSPECTION [MZR-CD (RF Turbo)].)
14	Is the engine compression correct? (See COMPRESSION INSPECTION [MZR-CD (RF Turbo)].)	Yes	Go to the next step.
14		No	Inspect for the following: • Damaged valve seat • Worn valve stem and valve guide • Worn or stuck piston ring • Worn piston, piston ring or cylinder • Improper valve timing Service if necessary.
15	Inspect the fuel injector. (See FUEL INJECTOR INSPECTION [MZR-CD (RF Turbo)].) Is the fuel injector normal?	Yes	Go to the next step.
15		No	Repair or replace if necessary.
16	Inspect the EGR system operation. Is the EGR system operation normal?	Yes	Go to the next step.
16		No	Repair or replace the malfunctioning part according to the EGR system operation results.
17	Inspect the EGR water cooler for the following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is the EGR water cooler normal?	Yes	Remove and inspect the supply pump and the common rail.
17		No	Service if necessary.
18	Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)