2003 lincoln ls v8 rough starts

[blacked03ls]

Anyone know why my car would have trouble starting after a day or two of sitting? It turns over but sometimes takes an additional second or two to fire up. plugs or coils? Also i have 68k on it, if i take it to the dealer can they check to see if all the coils are fine for free? I remember hearing that the coils are backed until 100,000 miles by the dealer. thanks

 

[joegr]

It could be the check valve in the fuel pump. Here is a quick test to find out.
After the car sits a day or two, turn the key to run (check engine and other lights come on), wait five seconds, and turn it back off for one or two seconds. Repeat this process one more time. Now start the car. If it starts up quickly, like it should, then you have confirmed that your problem is that gas is bleeding out of the fuel rail over time. Usually this will be due to a leaking injector or a bad check valve in the fuel pump. If it is a leaking injector, then you should have flooding issues too. (Engine would run ruff for a few seconds when you start it sometimes.)