As far as I know that info was wrong and it will now be in anti-theft with that module. PATS may be flashing a code and there will be a PATS code stored.

 

Those Jaguars XJ8s can be very finicky if the battery voltage drops much below 12VDC while cranking. Yes, quite finicky. If it were me, I would definitely connect a meter to the battery, and observe the voltage while cranking. By chance, you wouldn't happen to have anything plugged into one of the cigarette lighters while the car is sitting idle, and even if the device isn't turned on?

 

What codes are currently present?

 

None, zero, zip, clean as a whistle code wise.

Interesting note, today at around 22 degrees I turned the key to accessory, waited 10 seconds and shifted up and down the tree a few times before starting and it fired up after maybe 10 cranks which is an 'improvement'. Once out and about I picked up two bottles of Chevron fuel cleaner and dumped them into a 1/4 tank of gas because why not. At 155k miles I figured it was due. My gut at this point is telling me it's somehow fuel related. I've never changed the filter but always used 93+ octane gas. Not even sure where it is. Once warmer I will change the plugs but those are only about 25k in so it may be a waste of time/money. Who knows, maybe the fuel cleaner does the trick. Is vapor lock still a thing with the newer Jaguars? Had that on one of my previous Jaguars, don't recall which one.

 

Hi usasnq,

You apparently didn't notice but I moved all your posts to your own thread, which you can access here:

https://www.jaguarforums.com/forum/x...y-cold-197017/

I would suggest that you stop installing new parts until you've had your car scanned by a diagnostic system capable of reading the proprietary Jaguar diagnostic trouble codes (DTCs). I have never encountered an X350 that didn't have at least some B, C or U codes flagged. Going with your gut on these cars becomes very expensive very quickly. See my post in your thread at the above link.

I would also suggest that if you want to cure the problem yourself, you should download and study the factory documentation so you understand what is different about starting the car when it is very cold and therefore what could be causing the issue. See post #15 in this thread for links to several key documents, and also visit the HOW TO quick links thread on the home page of this X350 forum to download the factory Workshop Manual in six sections.

I'll give you a day to see this, then move these posts to your new thread at the link above.

Cheers,

Don