Nissan Sentra idles to HIGH AND SHAKES HELP!!

[duffman1278]

Well the check engine light on my sisters Sentra came on and the OBD II reader says that it is a "p0300 multiple cyclinder misfire detection" According to her and my brother n law the car idles at about 1500RPM when you start the car in the morning. They say that it also shakes at that idle speed for about 30 sec. and than stops shaking, but retains the same high idle. Than when you drive it goes back to normal. PLZ, any suggestions would help. BTW the following was just replaced, CAS and spark plugs.o

[duffman1278]

Any one???

[boriquaS13]

What year sentra is it? Obviosly 96 and newer being its obdII. Does it have coil on plug, depends on year. Do you happen to know what the symptom was before changing the cas sensor? No start? Check Eng Light?Multiple cylinder missfire could be caused by many things ie: vacuum leaks, bad Ignition wires or Ignition coils, egr stuck open if applicable or maybe they could have installed the cas incorrectly. Dunno, more info would be great!

[duffman1278]

Its an 01, The CAS was changed a year ago i believe becuase of recall? But it used to run just fine with no obvious issues.