Go to Symptom Troubleshooting



Symptom #10 - Engine stalls, runs rough, misses, bucks, hesitates or surges




Possible Causes


Diagnostic Procedure

1.  Verify vacuum hose connections, check the air filter, check for leakage or restriction of the intake-air system, ensure proper sealing of intake manifold and components attached (e.g. EGR, IAC), examine ignition components, fuel quality, and electrical connections.  Are all items okay?

2.  Check for stored OBD-II error codes.  Are there any stored codes?

3.  Is engine overheating?

4.  Connect an OBD-II scan tool capable of logging sensor output and drive the vehicle.  Are engine speed (RPM), mass-airflow (MAF), throttle position (TP), and vehicle speed (VSS) PIDs within specifications?

5.  Visually inspect the crankshaft position sensor and the teeth on the crankshaft pulley.  Are these components okay?

6.  Measure the gap between the crankshaft position sensor and the teeth of the crankshaft pulley (specification: 0.5-1.5mm).  Is the gap within specification?

7.  Check spark plug condition.  Are spark plugs wet, grayish white, or covered with carbon soot?

8.  Remove PCV valve and shake PCV valve.  Does the valve rattle?

9.  Verify that the throttle lever is resting on the throttle valve stop screw and/or throttle valve orifice plug.  Are there any faults present?

10.  Is there an exhaust restriction?

11.  Check fuel pressure between fuel filter and fuel rail.  Connect a jumper wire between the F/P terminal at the engine bay DLC connector and ground.  Is the fuel line pressure within specification (280-330kPa or 41-48psi) with the ignition switch on?

12.  Does fuel pressure increase when the accelerator is depressed?

13.  Skip to the next step if the symptom occurs with or without the A/C running.  If symptom occurs only with A/C operation, connect a pressure gauge to the A/C line and measure both low and high side pressures.  Are the pressures within specifications?

14.  Skip to the next step if the symptom  occurs with or without cruise control operation.  If symptom occurs only during cruise control operation, inspect the cruise control system.  Is cruise control system operating properly?

15.  Is the evaporative emissions purge control system okay?

16.  Visually inspect the camshaft pulley, is the camshaft pulley okay?

17.  With the engine idling, disconnect the vacuum hose from the EGR valve and plug it.  Is the engine condition improved?

18.  Is the air-bypass valve actuator okay?

19.  Check engine compression with a cylinder compression test tool.  Is the engine compression within specifications?

20.  Verify test results.  If okay, return to diagnostic index to service any additional symptoms.  If vehicle is repaired, troubleshooting is complete.  If vehicle is not repaired or additional diagnostic information is not available, replace the ECU.