NO.11 ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE, SURGES


11	ENGINE STALLS/QUITS - ACCELERATION/CRUISE ENGINE RUNS ROUGH - ACCELERATION/CRUISE MISSES - ACCELERATION/CRUISE BUCK/JERK - ACCELERATION/CRUISE/DECELERATION HESITATION/STUMBLE - ACCELERATION SURGES - ACCELERATION/CRUISE
DESCRIPTION	• The engine stops unexpectedly at the beginning of acceleration or during acceleration. • The engine stops unexpectedly while cruising. • The engine speed fluctuates during acceleration or cruising. • The engine misses during acceleration or cruising. • The vehicle bucks/jerks during acceleration, cruising, or deceleration. • A momentary pause at the beginning of acceleration or during acceleration • A momentary minor irregularity in the engine output
POSSIBLE CAUSE	• Vacuum leakage • Air leakage from intake-air system • Air cleaner restriction • Air suction at intake-air system (between MAF sensor and intake ports) • Improper operation of drive-by-wire control system (abnormal accelerator position and TP signals to PCM) • Throttle body malfunction (stuck close) • Improper SSV operation • Improper APV operation* • Poor fuel quality • Inadequate fuel pressure • Fuel pump mechanical malfunction • Fuel leakage from fuel injector • Fuel injector clogging • Fuel injector improper operation • Fuel line restriction or clogging • Pressure regulator (integrated in fuel pump unit) malfunction • Intermittent open or short in fuel pump body circuit • Fuel pump relay malfunction (stuck open) • Restriction in exhaust system • Purge solenoid valve malfunction • Improper air/fuel ratio control • MAF sensor improper installation • Intermittent open or short of MAF sensor, TP sensor, APP sensor and VSS • Erratic signal from eccentric shaft position sensor	• Improper ignition timing control (abnormal ECT, IAT, MAF and knock signals to PCM) • Improper fuel injection control (abnormal MAF, ECT, and front/rear HO2S signals to PCM) • Improper load signal (neutral/CPP switch (MT), TR switch (AT)) to PCM • Main relay intermittent malfunction • Low engine compression – Engine internal malfunction – Abnormal engine oil condition (viscosity, deterioration) – Low oil pressure – Excessive fuel pressure – Air mixed in oil line – Metering oil pump malfunction • Leakage or clogging in oil pipe • Leakage or clogging in oil nozzle • Metering oil pump malfunction • Improper metering oil pump control operation • Engine overheating • Spark leakage from high-tension leads • Spark plug malfunction • Improper A/C system operation • Improper torque converter clutch control operation (AT) • Improper shift point (AT) • AT malfunction (AT) • Clutch slippage (MT)
POSSIBLE CAUSE	Warning The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read the following warnings before servicing the fuel system: • 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 injuries 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. (See BEFORE REPAIR PROCEDURE.) (See AFTER REPAIR PROCEDURE.) Caution • Disconnecting/connecting quick release connector without cleaning it may possibly cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.


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: • Vacuum connection • Air cleaner element • No air leakage from intake-air system • No restriction of intake-air system • Blockage of intake-air system (between MAF sensor and intake ports) • Ignition wiring • Fuel quality (e.g. proper octane, contamination, winter/summer blend) • MAF sensor installation • Electrical connections • 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. Retrieve any continuous memory, KOEO and KOER DTCs. If the stall condition exists, retrieve the continuous memory and the KOEO 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	Connect the WDS or equivalent to the DLC-2. Access APP, RPM, VPWR, MAF, TP_REL, O2S11, O2S12 and VSS PIDs. Drive the vehicle while monitoring PIDs. Are the PIDs within specifications? (See PCM INSPECTION.)	Yes	Go to the next step.
5		No	APP PIDs: Inspect if the output signal from the APP sensor changes smoothly. RPM PID: Inspect the eccentric shaft position sensor and the related wiring harness for vibration or an intermittent open/short circuit. If normal, go to the next step. VPWR PID: Inspect for an intermittent open circuit. MAF PID: Inspect for an intermittent open circuit of the MAF sensor and the related wiring harness. TP_REL PID: Inspect if the output signal from the TP sensor changes smoothly. O2S11 PID: Inspect the front HO2S and the related wiring harness for vibration or an intermittent open or short circuit or both. If normal, go to Step 8. O2S12 PID: Inspect the rear Ho2S and the related wiring harness for vibration or an intermittent open or short circuit or both. If normal, go to Step 8. VSS PID: Inspect DSC system. (See DTC Table.)
6	Inspect the knock sensor. (See KNOCK SENSOR (KS) INSPECTION.) Is the knock sensor normal?	Yes	Go to the next step.
6		No	Replace the knock sensor. (See KNOCK SENSOR (KS) REMOVAL/INSTALLATION.)
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	Is a strong blue spark visible at each disconnecting high-tension lead while cranking the engine?	Yes	Inspect for the following: • Spark plugs malfunction • Spark plugs heat range • Pulse wheel damaged on eccentric shaft • Open or short circuit on the eccentric shaft position sensor • Open or short between the eccentric shaft position sensor and PCM terminal 2U or 2X If they are normal, go to the next step.
8		No	Inspect the following: • High-tension leads • Ignition coils or connectors
9	Inspect the spark plug conditions. 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.
9		No	Install the spark plugs in the original positions. Go to the next step.
10	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.
10		No	Repair or replace the malfunctioning part according to the drive-by-wire system operation inspection results.
11	Visually inspect the exhaust system part. Is there any deformed exhaust system part?	Yes	Replace the suspected part.
11		No	Go to the next step.
12	Perform the fuel pump speed control operation inspection. (See Fuel Pump Speed Control Operation Inspection.) Does the fuel pump speed control operate properly?	Yes	Go to the next step.
12		No	Repair or replace the malfunctioning parts, according to the fuel pump speed control operation inspection results.
13	Install the fuel pressure gauge to the fuel line quick release connector. Short the check connector terminal F/P to the body GND using a jumper wire. Turn the ignition switch to the ON position. Is the fuel line pressure correct with the ignition switch in the ON position? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Go to the next step.
13		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.)
14	Visually inspect for fuel leakage at the fuel injector O-ring and fuel line. Service if necessary. Is the fuel line pressure held after the ignition switch is turned off? (See FUEL LINE PRESSURE INSPECTION.)	Yes	Go to the next step.
14		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.)
15	Perform the fuel injector operation inspection. (See Fuel Injector Operation Inspection.) Are the fuel injectors operating properly?	Yes	Go to the next step.
15		No	Repair or replace the malfunctioning parts, according to the fuel pump speed control operation inspection results.
16	Inspect the fuel injectors for the following: (See FUEL INJECTOR INSPECTION.) • Leakage • Clogging • Injection amount Are the injectors normal?	Yes	Go to the next step.
16		No	Replace the fuel injector. (See FUEL INJECTOR REMOVAL/INSTALLATION.)
17	Note • The following test is for an engine stalling with the A/C on. If other symptom exists, go to the next step. Connect a pressure gauge to the A/C low and the high pressure side lines. Turn the A/C on and measure the low side and high side pressure. Are the pressures within the specifications? (See REFRIGERANT PRESSURE CHECK.)	Yes	Go to the next step.
17		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 • Condenser fan operation
18	Note • The following test should be performed for a symptom with the cruise control on. If other symptoms exist, go to the next step. Inspect the cruise control system. Is the cruise control system normal?	Yes	Go to the next step.
18		No	Repair or replace the malfunctioning parts.
19	Perform the SSV operation inspection. (See Secondary Shutter Valve (SSV) Operation Inspection.) Does the SSV operate properly?	Yes	Go to the next step.
19		No	Repair or replace the malfunctioning parts, according to the SSV operation inspection results.
20	Note • The following test is for 13B-MSP (High Power). Go to the next step 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.
20		No	Repair or replace the malfunctioning parts, according to the APV control inspection results.
21	Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side. Plug the opening end of the vacuum hose. Drive the vehicle. Does the engine condition improve?	Yes	Go to the next step. Inspect if the purge solenoid valve sticks open mechanically. Inspect the evaporative emission control system.
21		No	Go to the next step.
22	Inspect the ignition timing. (See Ignition Timing Inspection.) Does the ignition timing operate properly?	Yes	Go to the next step.
22		No	Repair or replace the malfunctioning parts, according to the ignition timing inspection results.
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 parts, according to the metering oil pump control inspection results.
24	Inspect the engine compression. (See COMPRESSION INSPECTION.) Is it normal?	Yes	Inspect the following: • Internal transmission components (AT) • Torque converter clutch control (AT) • Shift point (AT) • Clutch (MT) • Brake system for dragging • Engine mounts • Knocking
24		No	Go to the next step.
25	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.
25		No	Repair or replace the malfunctioning part according to inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
26	Check the engine oil connection. 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 Workshop Manual.)
26		No	Go to the next step.
27	Inspect the oil pressure. (See OIL PRESSURE INSPECTION.) Is the oil pressure within the specification?	Yes	Go to the next step.
27		No	Repair or replace the malfunctioning part according to the inspection results. After that overhaul or replace the engine. (See Engine Workshop Manual.)
28	Turn the ignition switch off. Disconnect the fuel line quick release connector and release 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.
28		No	Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) After that overhaul or replace the engine. (See Engine Workshop Manual.)
29	Check the oil pipe between the metering oil pump and the metering oil nozzle. Is there any air and/or clogging in the oil pipe?	Yes	Inspect and repair for leakage and/or clogging in the oil passage at engine. After that overhaul or replace the engine. (See Engine Workshop Manual.)
29		No	Overhaul or replace the engine. (See Engine Workshop Manual.)
30	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis.