No.8 Engine Runs Rough/Rolling Idle: Notes

DESCRIPTION & POSSIBLE CAUSE

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	Engine overheating PCM DTC is stored Erratic signal to PCM APP sensor or related circuit malfunction ECT sensor No.1 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 air/fuel mixture ratio control operation 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 Unbalanced fuel injection amount for each cylinder 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 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 Erratic signal from CKP sensor Loose installation Damaged trigger wheel (crankshaft pulley) 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 (built-into high pressure fuel pump) malfunction Relief valve (built-into high pressure fuel pump) malfunction Fuel pump (low-side) body mechanical malfunction Fuel filter clogged Fuel injector 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 or excessive unbalance for each cylinder Improper intake valve timing Improper exhaust valve timing Spark plug malfunction Incorrect signal to ignition coil Exhaust system or TWC restricted or clogged PCV valve malfunction Injector driver (built-into PCM) 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 ). (See AFTER SERVICE PRECAUTION ). 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.

CAUTION:

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

RELATED PIDs DESCRIPTION

Monitor item (Definition)	Unit/Condition	Condition/Specification (Reference)
ECT	°C, °F	Displays the ECT
ECT	V	ECT is 20°C {68°F}: approx. 3.10 V ECT is 40°C {104°F}: approx. 2.16 V ECT is 60°C {140°F}: approx. 1.40 V ECT is 80°C {176°F}: approx. 0.87 V ECT is 100°C {212°F}: approx. 0.54 V
APP1	%	Accelerator pedal released: approx. 16 % Accelerator pedal depressed: approx. 80 %
APP1	V	Accelerator pedal released: approx. 0.8 V Accelerator pedal depressed: approx. 4 V
APP2	%	Accelerator pedal released: approx. 8 % Accelerator pedal depressed: approx. 40 %
APP2	V	Accelerator pedal released: approx. 0.4 V Accelerator pedal depressed: approx. 2 V
MAF	g/sec	Displays the MAF
MAF	V	Switch the ignition to ON (MAF: 0.59 g/s {0.078 lb/min}): approx. 0.72 V Idle (after warm up) (MAF: 2.17 g/s {0.287 lb/min}): approx. 0.86 V Racing (engine speed is 2,000 rpm ) (MAF: 4.73 g/s {0.626 lb/min}): approx. 1.07 V
MAP	KPa {MPa}, mBar {Bar}, psi, in H20	Displays the MAP
MAP	V	Switch the ignition to ON (MAP: 101 kPa {1.03 kgf/cm ² , 14.6 psi}): approx. 4.07 V Idle (after warm up) (MAP: 33 kPa {0.34 kgf/cm ² , 4.8 psi}): approx. 1.34 V Racing (engine speed is 2,000 rpm ) (MAP: 26 kPa {0.27 kgf/cm ² , 3.8 psi}): approx. 1.05 V
VSS	KPH, MPH	Displays the vehicle speed
RPM	RPM	Displays the engine speed
O2S11	A	Idle (after warm up): approx. -39 μA Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): approx. 3.84 mA
O2S12	V	Idle (after warm up): 0-1.0 V Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): approx. 0 V
SHRTFT1	%	Idle (after warm up): approx. 1.56 % Racing (engine speed is 2,000 rpm ): approx. -3.12 % Racing (engine speed is 4,000 rpm ): approx. -8.59 %
LONGFT1	%	Idle (after warm up): approx. -2.34 % Racing (engine speed is 2,000 rpm ): approx. -0.78 % Racing (engine speed is 4,000 rpm ): approx. -0.78 %
AC_REQ	OFF/ON	A/C switch OFF: Off A/C switch ON: On
TPREL	%	Accelerator pedal released: approx. 12 % Accelerator pedal depressed: approx. 82 %
FUEL_PRES	KPa {MPa}, mBar {Bar}, psi, in H20	Displays the fuel pressure
FUEL_PRES	V	Fuel pressure is 3.0 MPa {31 kgf/cm ² , 435 psi}: approx. 0.92 V Fuel pressure is 4.8 MPa {49 kgf/cm ² , 696 psi}: approx. 1.17 V
LOAD	%	Idle (after warm up): approx. 16.07 % Racing (engine speed is 2,000 rpm ): approx. 14.51 % Racing (engine speed is 4,000 rpm ): approx. 21.17 %