NO.10 ENGINE STALLS/QUITS, ENGINE RUNS ROUGH, MISSES, BUCK/JERK, HESITATION/STUMBLE, SURGES [F2]

id010394850300

10

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 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 beginning of acceleration or during acceleration
•  Momentary minor irregularity in engine output
POSSIBLE CAUSE
•  A/C system operation is improper.
•  Air leakage from intake-air system parts
•  Purge solenoid valve malfunction
•  IAC valve improper operation
•  Erratic signal from CMP sensor
•  Low engine compression
•  Vacuum leakage
•  Poor fuel quality
•  Spark leakage from high-tension leads
•  Air cleaner restriction
•  PCV valve malfunction
•  Improper valve timing due to jumping out timing chain
•  Restriction in exhaust system
•  Intermittent open or short circuit in fuel body pump circuit
•  Inadequate fuel pressure
•  Fuel pump mechanical malfunction
•  Fuel leakage from fuel injector
•  Fuel injector clogging
•  Intermittent open or short circuit of MAF sensor, TP sensor and VSS
•  Clutch slippage
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 SERVICE PRECAUTION” and “AFTER SERVICE PRECAUTION” described in this manual.

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION
1
Verify the 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 (such as proper octane, contamination, winter/summer blend)
•  Electrical connections
•  Smooth operation of throttle valve
Are all items normal?
Yes
Go to the next step.
No
Service if necessary.
Repeat Step 1.
2
Connect the M-MDS to the DLC-2.
Turn the ignition switch to the ON position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?
Yes
DTC is displayed:
•  Go to appropriate the DTC inspection.
No
No DTC is displayed:
•  Inspect instrument cluster operation.
3
Is the engine overheating?
Yes
Go to symptom troubleshooting “No.16 Cooling system concerns - Overheating”.
(See NO.16 COOLING SYSTEM CONCERNS-OVERHEATING [F2].)
No
Go to the next step.
4
Connect the M-MDS to the DLC-2.
Access RPM, VPWR, MAF, TP and VSS PIDs.
•  RPM PID
•  VPWR PID
•  TP PID
•  MAF PID
•  VSS PID
Drive vehicle with monitoring PIDs.
Are PIDs within specifications?
(See PCM INSPECTION [F2].)
Yes
Go to the next step.
No
RPM PID:
Inspect the CMP sensor and related harness for such as vibration, intermittent open/short circuit.
VPWR PID:
Inspect for open circuit intermittently.
MAF PID:
Inspect for open circuit of the MAF sensor and related wire harness intermittently.
TP PID:
Inspect if output signal from the TP sensor changes smoothly.
VSS PID:
Inspect for open circuit of the VSS and related wire harness intermittently.
5
Visually inspect the CMP sensor.
Is CMP sensor normal?
Yes
Go to the next step.
No
Replace the malfunctioning part.
6
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 the fuel injector.
No
Install spark plugs on original cylinders.
Go to the next step.
7
Remove and shake the PCV valve.
Does the PCV valve rattle?
Yes
Go to the next step.
No
Replace the PCV valve.
8
Verify that throttle lever is resting on throttle valve stop screw and/or throttle valve orifice plug.
Is lever in correct position?
Yes
Go to the next step.
No
Adjust as necessary.
9
Are there restrictions in the exhaust system?
Yes
Inspect exhaust system.
No
Go to the next step.
10
Install fuel pressure gauge between the fuel pipe and the fuel distributor.
Connect jumper wire between F/P terminal at DLC in engine compartment and ground.
Turn the ignition switch to the ON position.
Is fuel line pressure correct with ignition switch on?
(See FUEL PUMP UNIT INSPECTION [F2].)
Yes
Go to the next step.
No
Zero or low:
Inspect fuel pump circuit.
Inspect for open fuel pump relief valve.
Inspect for fuel leakage inside pressure regulator.
Inspect for clogged main fuel line.
High:
•  Inspect pressure regulator for high pressure cause.
•  Inspect for clogged fuel return line.
11
Visually inspect for fuel leakage at the fuel injector O-ring and fuel line.
Service if necessary.
Does fuel line pressure hold after ignition switch is turned off?
(See FUEL PUMP UNIT INSPECTION [F2].)
Yes
Go to the next step.
No
Inspect the pressure regulator diaphragm condition.
•  If the condition is normal, inspect the fuel injector.
•  If the condition is not normal, replace the pressure regulator.
12
Install vacuum gauge to intake manifold.
Start engine.
Does fuel pressure gauge reading increase as vacuum gauge reading decreases and/or does fuel pressure gauge reading decrease as vacuum reading increases?
Yes
Go to the next step.
No
Connect vacuum hose to pressure regulator.
Start engine
Verify that fuel pressure gauge reading changes as vacuum changes.
If it changes, inspect vacuum line.
If it does not change, replace pressure regulator.
13
Note
•  Following test is for 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 high pressure side lines.
Turn the A/C on and measure low side and high side pressure.
Are pressure within specifications?
(See REFRIGERANT PRESSURE CHECK.)
Yes
Go to the next step.
No
If the A/C is always on, go to symptom troubleshooting “No.23 A/C is always on or A/C compressor runs continuously”.
(See NO.23 A/C IS ALWAYS ON/A/C COMPRESSOR RUNS CONTINUOUSLY [F2].)
For other symptoms, inspect the following:
•  Refrigerant charging amount
14
Disconnect the vacuum hose between the purge solenoid valve and the dynamic chamber from purge solenoid valve side.
Plug the opening end of the vacuum hose.
Drive the vehicle.
Does engine condition improve?
Yes
Inspect if the purge solenoid valve is stuck open mechanically.
Inspect the EVAP control system.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [F2].)
No
Go to the next step.
15
Is engine compression correct?
(See COMPRESSION INSPECTION [F2].)
Yes
Inspect the following:
•  Valve timing.
•  Clutch
No
Inspect for cause.
16
•  Verify test results.
―  If normal, return to diagnostic index to service any additional symptoms.
―  If malfunction remains, inspect related Service Information and perform repair or diagnosis.
•  If vehicle is repaired, troubleshooting completed.
•  If vehicle is not repaired or additional diagnostic information is not available, replace the PCM.