Possible causes are :
 FUEL SYSTEM
Excessive fuel pressure, check for leaking or bad injector, leaking fuel pressure regulator, low fuel pressure, engine low on fuel, vapor recovery system fault.
 INTAKE SYSTEM
leaking air after NAF sensor, intake gasket, vacuum leaks, PCV valve
 EGR system
check EGR valve if stuck or leaking check for exhaust leak before or near the O2 sensor, check oil, check cam timing
do u have any symptom :lack of power, spark knock, buck, jerk, hesitation on acceleration
if so suspect MAF sensor
Tuesday, November 4th, 2008 AT 6:21 AM