The battery is about a year old, and I trickled charged it the night before to make sure it was not low charge when cranking it as a test, but this car takes longer and longer to start over the last couple months; I only drive it 2-3 times a week.

I have not gotten the 'ASC/Trac warnings' that I got when the battery was either low charge, or on the way out.

I'm trying to figure out why it would take longer to crank when cold, approx 2x longer over the course of a few months.

I assumed it's a worn starter, but 1-3 time week starting the car doesn't seem like much wear for a few years.

 

Some easier places to look would be:
Coolant temp sensor giving the wrong reading especially when cold,
Not enough pressure in the fuel line overnight, try to cycle the key few times before starting to build up pressure
Too heavy engine oil may add second or two to the cranking time when cold.
Low battery would make each crank remarkably slower
J.

 

First it would be most helpful if we knew what the model year and type of vehicle you are working on. You can go to the USER CP and add that info to your signature line and it will always appear.
The starting sequence for the Jaguar is to turn the key to the first position and the lights and self diagnosis will come on. During that time the fuel pump comes on for 3 to 5 seconds to charge the rack. Once the lights go out turn the key to the starting position and the engine will begin to crank.. The CKPS (crankshaft position sensor) will detect rotation and signal the ECM (engine control module) that the engine is cranking and the ECM will add the appropriate fuel and spark.
An incorrect reading engine temperature sensor will signal for a warm engine and the ECM will fuel appropriately. A dirty and faulty CKPS will not signal engine rotation and the ECM will not fuel.
I would first remove and clean the face of the CKPS and also disconnect and clean the connections for both the engine temp sensor and the CKPS. If you do not know the age and condition of the fuel filter I would also change it out. There is one last connection that will also affect the starting and that is the ground strap that runs from the engine/transmission joint to the frame rail on the underside of the vehicle about 12 to 18 inches behind the right front tire. Inspect and clean the mounting for it.
If the starter is rotating normally and not at a slower than normal speed then there is probably nothing wrong with it. Continued long cranking will damage it.

 

I agree with most of Vern's thoughts: Still, this is my choice

"An incorrect reading engine temperature sensor will signal for a warm engine and the ECM will fuel appropriately."

Happens every year as the weather changes. The ECU thinks it is warm out because a bad sensor is not reading correctly, yet it needs an enriched first shot. Change the temperature sensor (a good time of the year to change the antifreeze, check the hoses and belts, and replace the crossover pipe where the temperature sensor is located -- most suppliers have a new sensor in a new pipe for very little money). I know, it doesn't get that cold in San Jose: doesn't take much.

Then clean the MAF, clean the throttle bore and plate and check for OBD II codes, and have the fuel filter renewed (use the big AC Delco one).
And is the battery new? Check the cables, be sure they are tight. Finally, a can of a good fuel system cleaner, BG44k, Lucas, Gumout's very best, might clean up the injectors. All this, maybe an hour or two of labor and $100 for parts (unless you need a new battery). I would find a reliable independent or dealer (they are all over the area) to change the fuel filter (I hate having gas drip in my face or crawling under the car!).

 

Thanks guys...I will first try cycling the fuel pump a few times to see if there is a change.

Then I will check the ground strap (should be easy)

I cleaned the throttle body and maf and egr a couple years ago....maybe only 7500 miles ago?

Then I will go to the temp sensors....kinda annoyed if it's that as I flushed the coolant and changed the water pump 2 months ago, and it would have been easier to do the others stuff at the same time, but oh well. :/

Battery is a year old...maybe a bit less.

Fuel filter has not been changed in a long, long time...:/