NO.11 ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE, SURGES [WITHOUT WU-TWC]

id0103008017c6

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.
• Momentary pause at the beginning of acceleration or during acceleration
• Momentary minor irregularity in engine output

POSSIBLE CAUSE

• A/C system operation is improper.
• Erratic signal or no signal from CMP sensor
• Air leakage from intake-air system parts
• Purge solenoid valve malfunction
• IAC valve improper operation
• Erratic signal from CKP sensor
• Low engine compression
• Vacuum leakage
• Poor fuel quality
• Main relay intermittent malfunction
• Throttle body malfunction
• Engine overheating
• Spark plug malfunction
• Improper air/fuel mixture ratio control operation
• Improper VTCS operation
• Erratic signal to ignition coil
• Air cleaner restriction
• PCV valve malfunction
• Improper valve timing due to jumping out timing belt
• Restriction in exhaust system
• Intermittent open or short in fuel body pump circuit
• Inadequate fuel pressure
• Fuel pump mechanical malfunction
• Fuel leakage from fuel injector
• Fuel injector clogging
• Fuel line restriction or clogging
• Pressure regulator malfunction
• TP sensor misadjustment
• Intermittent open or short of MAF sensor, TP sensor and VSS
• ATX malfunction (ATX)
• Clutch slippage (MTX)
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 injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the "BEFORE REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this manual.
(See BEFORE REPAIR PROCEDURE.)
(See AFTER REPAIR PROCEDURE.)
Caution
• If there is foreign material on the connecting area of the quick release connector, it might damage the connector or fuel pipe. To prevent this, disconnect the connector and clean the connecting area before connecting.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Inspect the for following:
• Vacuum connection
• Air cleaner element
• No air leakage from the intake-air system
• No restriction of the intake-air system
• Proper sealing of the intake manifold and components attached to the intake manifold: such as the IAC valve
• Ignition wiring
• Fuel quality (e.g. proper octane, contamination, winter/summer blend)
• Electrical connections
• Smooth operation of the throttle valve
Are all items normal?
Yes
Go to the next step.
No
Service if necessary.
Repeat Step 1.
2
Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
If a stall condition exists a retrieve continuous memory and KOEO DTCs.
Are any DTCs displayed?
Yes

DTC is displayed:

Go to the appropriate DTC test.
No

No DTC is displayed:

Go to the next step.
3
Is the engine overheating?
Yes
Go to the symptom troubleshooting "No.17 Cooling system concerns - Overheating".
No
Go to the next step.
4
Connect the WDS or equivalent to the DLC-2.
Access RPM, VPWR, MAF, TP, and VSS PIDs.
Monitor the PIDs while driving the vehicle.
Are PIDs within specifications?
Yes
Go to the next step.
No

RPM PID:

Inspect the CKP sensor and the related harness for vibration and intermittent open/short circuit.

VPWR PID:

Inspect for an intermittently open circuit.

MAF PID:

Inspect for an intermittently open circuit of MAF sensor and the related wire harness.

TP PID:

Inspect if the output signal from TP sensor changes smoothly.

VSS PID:

Inspect for an intermittently open circuit of the VSS and the related wire harness intermittently.
5
Visually inspect the CKP sensor and teeth of the crankshaft pulley.
Are the CKP sensor and teeth of the crankshaft pulley normal?
Yes
Go to the next step.
No
Replace the malfunctioning parts.
6
Measure the gap between the CKP sensor and teeth of the crankshaft pulley.
Specification

0.5-1.5 mm {0.02-0.05 in}

Is the gap within specification?
Yes
Go to the next step.
No
Replace the plate.
7
Inspect the spark plugs.
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 fuel injector.

Spark plug is grayish white:

Inspect for clogged fuel injector.
No
Install spark plugs on original cylinders.
Go to the next step.
8
Remove and shake the PCV valve.
Does the PCV valve rattle?
Yes
Go to the next step.
No
Replace the PCV valve.
9
Verify that the throttle lever is resting on the throttle valve stop screw and/or the throttle valve orifice plug.
Is the lever in correct position?
Yes
Go to the next step.
No
Adjust if necessary.
10
Inspect for restriction in the exhaust system.
Is there any restriction?
Yes
Inspect the exhaust system.
No
Go to the next step.
11
Install a fuel pressure gauge between the fuel pipe and the fuel distributor.
Connect the WDS or equivalent to the DLC-2.
Turn on the fuel pump using the FP PID in the output state control of the datalogger function.
Is the fuel line pressure correct?
Yes
Go to the next step.
No

Zero or low:

Inspect the fuel pump relay and the fuel pump related circuits.
Inspect for fuel leakage inside the pressure regulator.
Inspect for a clogged main fuel line.

High:

Inspect the pressure regulator for the cause of high pressure.
Inspect for a clogged fuel return line.
Inspect the vacuum hose to the pressure regulator.
12
Visually inspect for fuel leakage at the fuel injector O-ring and fuel line.
Service if necessary.
Is fuel line pressure held after the FP PID is turned off?
Yes
Go to the next step.
No
Inspect the pressure regulator diaphragm.
• If the condition is normal, inspect the fuel injector.
• If the condition is not normal, replace the pressure regulator.
13
Note
• The Following test is for engines stalling with A/C on. If other symptoms exist, go to the next step.
Connect a pressure gauge to the A/C low and high pressure side lines.
Turn the A/C on and measure the low side and high side pressure.
Are the pressures within specification?
Yes
Go to the next step.
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".
For other symptoms, inspect the following:
• Refrigerant charging amount
• Condenser fan operation
14
Disconnect the vacuum hose between the purge solenoid valve and the intake manifold from the purge solenoid valve side.
Plug opening end of the vacuum hose.
Drive the vehicle.
Does engine condition improve?
Yes
Go to the next step.
Inspect if the purge solenoid valve sticks open mechanically.
Inspect evaporative emission control system.
No
Go to the next step.
15
Visually inspect the CMP sensor and projections of the camshaft pulley.
Are the CMP sensor and projections of the camshaft pulley normal?
Yes
Go to the next step.
No
Replace the malfunctioning parts.
16
Inspect the VTCS operation.
Is VTCS normal?
Yes
Go to the next step.
No
Replace or replace the malfunctioning parts.
17
Is the engine compression correct?
Yes
Inspect the following:
• Valve timing.
• Internal transaxle part (ATX)
• Clutch (MTX)
No
Inspect for the cause.
18
Verify test results.
• If normal, return to the diagnostic index to service any additional symptoms.
• If the malfunction remains, replace or reprogram the PCM.