Nissan Repair: 2003 Nissan Sentra GXE hard to start when cold, variable valve timing, nissan sentra

Question
Car is hard to start in the morning when it is cold, I have to keep giving it gas so it will start to run then finally after it will stay running I have to let it warm up 10-15 minutes to keep it from stalling.  The check engine light was on and had it check at the dealers code P0340 they said they replaced the the cam shaft but it still isn't working.  They said I need a valve timing control sprocket??? What do you think? past recall for this type of car said to replace timing sensor, What do you think?


Answer
Al,

If the variable valve timing is not working when the engine is cold it could need the timing control.  I can't see the car so I can only assume they know what they are talking about.  Once the car is warm it runs fine?  If that is the case it could be a plugged oil gallery that is opening up once the car is warm.  Now, it could be as simple as the temperature sensor that tells the computer that the car is cold.  This allows the car to run in rich mode until it warms up.  Then all is fine and the car runs good.  If this is the case I would replace the sensor first as this is much cheaper than replacement of the timing control.  I would want objective evidence from the dealer before plunking down the kind of cash required to replace the valve timing control unit.