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 position sensor misadjustment • Accelerator 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 REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.


STEP	INSPECTION	RESULTS	ACTION
1	Inspect for 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 okay?	Yes	Go to next step.
1		No	Service as necessary Repeat Step 1.
2	Is engine overheating?	Yes	Go to symptom troubleshooting "NO.17 COOLING SYSTEM CONCERNS-OVERHEATING."
2	Is engine overheating?	No	Go to next step.
3	Connect WDS or equivalent to DLC-2. Turn engine switch to ON. Retrieve any DTC. Is DTC displayed?	Yes	DTC is displayed: Go to appropriate DTC test. Communication error message is displayed: Inspect for 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 next step.
4	Does engine run normal after warm-up?	Yes	Inspect glow system operation. (See RELAY INSPECTION.) Replace any malfunctioning part as necessary. If glow system is okay, go to next step.
4	Does engine run normal after warm-up?	No	Go to next step.
5	Note • The following test should be performed on the vehicles with A/C system. If the following test cannot be performed due to engine stalling, go to next step. • Go to next step for the vehicle without A/C system. Connect pressure gauge to A/C line. Turn blower and A/C switches on. Is pressure within specifications?	Yes	Go to 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". Other symptoms: Inspect for following: • Refrigerant charging amount • Cooling fan and/or condenser fan operation
6	Depress accelerator pedal slightly. Crank engine. Does engine start now?	Yes	Inspect idle speed. (See IDLE SPEED INSPECTION [MZR-CD (RF Turbo)].)
6		No	Go to next step.
7	Inspect adjustment of accelerator position sensor and idle switch. (See ACCELERATOR POSITION SENSOR INSPECTION [MZR-CD (RF Turbo)].) (See IDLE SWITCH INSPECTION [MZR-CD (RF Turbo)].) Are accelerator position sensor and idle switch adjusted correctly?	Yes	Go to next step.
7		No	Adjust accelerator position sensor and idle switch correctly. (See ACCELERATOR POSITION SENSOR ADJUSTMENT [MZR-CD (RF Turbo)].) (See IDLE SWITCH ADJUSTMENT [MZR-CD (RF Turbo)].)
8	Inspect for fuel leakage from fuel pipe. Is any fuel leakage found on fuel pipe?	Yes	Repair or replace as necessary.
8		No	Go to next step.
9	Visually inspect CKP sensor and teeth of pulse wheel. Are CKP sensor and teeth of pulse wheel okay?	Yes	Go to next step.
9		No	Replace malfunctioning parts.
10	Measure gap between CKP sensor and teeth of pulse wheel. Specification 1.5-2.5 mm {0.059-0.098 in} Is gap within specification?	Yes	Go to next step.
10		No	Adjust CKP sensor position.
11	Visually inspect CMP sensor and teeth of pulse wheel. Are CMP sensor and teeth of pulse wheel okay?	Yes	Inspect following PIDs: (See PCM INSPECTION [MZR-CD (RF Turbo)].) • ECT • IAT • MAF • MAP • RPM If PID value is not as specified, repair or replace malfunctioning parts. If PID value is okay, go to next step.
11		No	Replace malfunctioning parts.
12	Inspect fuel pressure sensor. (See FUEL PRESSURE SENSOR INSPECTION [MZR-CD (RF Turbo)].) Is fuel pressure okay?	Yes	Go to next step.
12		No	Replace common rail.
13	Inspect suction control valve. (See SUCTION CONTROL VALVE INSPECTION [MZR-CD (RF Turbo)].) Is suction control valve okay?	Yes	Go to next step.
13		No	Repair supply pump. (See SUPPLY PUMP INSPECTION [MZR-CD (RF Turbo)].)
14	Is engine compression correct? (See COMPRESSION INSPECTION [MZR-CD (RF Turbo)].)	Yes	Go to next step.
14		No	Inspect for 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 as necessary.
15	Inspect fuel injector. (See FUEL INJECTOR INSPECTION [MZR-CD (RF Turbo)].) Is fuel injector okay?	Yes	Go to next step.
15		No	Repair or replace as necessary.
16	Inspect EGR system operation. Is EGR system operation normal?	Yes	Go to next step.
16		No	Repair or replace malfunctioning part according to EGR system operation results.
17	Inspect EGR water cooler for following: • Coolant passage clogging/restriction • Exhaust gas clogging/restriction Is EGR water cooler okay?	Yes	Remove and inspect supply pump and common rail.
17		No	Service as necessary.
18	Verify test results. • If okay, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)