I have a 2001 S40 Auto.

After the car sits for awhile like over night I go to start the car it tries fire and then you just hear the starting turning but doesn't start. but I hit the gas pedal it fires right up but have to let it rev for a little bit before it stays at idle. But if i drive it somewhere and turn it off walk into a store and walk back out it will start back up with just the turn of the key but if it sits for 3hrs+. It will do the above. Been thinking maybe the battery but it starts. So any ideas would be appreciated.

Thanks

 

There is 2 most common problem when the described problem happens.The FPR (Fuel Pressure Regulator) which tends to go bad after a while and the IAC (Idle Control Valve) which gets dirty and sticky.I would start to clean the IAC first as it seems like the problem here.You can read up on how-to do it here:
http://s40concepts.net/forum/index.p...65ad9bcdac6126
If your problem still persist then you should get a new FPR.

 

Had the same problem with my S40. New FPR cured it. Quick fix, easy to install.

 

+1,+1,+1

 

fuel pressure regulator +1