2001 S type 4.0..this started as a slight miss after driving at highway speeds for twenty minutes. It still does that but now the engine stumbles and has a slight miss at idle about every five seconds cold or warm. It doesn’t last long enough to register on the tach but you can feel the car shake. I have checked the fuel trims with two different devices and they are basically the same readings as follows:
STFT BANK ONE. -6.3 to 1.56
LTFT BANK ONE. +2.34
STFT BANK TWO. -6.25 to 2.34
LTFT BANK TWO. basically a steady 0

fuel pressure runs about 55 psi if I remember correctly and there are no codes set. The car runs pretty good but this miss might well turn into a shut off at a bad time. Also I noticed that when I hit the throttle pretty hard with the car in park it doesn’t want to rev above 2800-3000 rpm regardless of pedal position. Is this normal or some safety thing I’m not aware of? I’m pretty good mechanically but Jaguars are a new world to me. This engine bay is still a mystery to me. I apologize if there are threads I missed or other facts I should have known before posting, but this forum was a great help to me with a battery drain problem ( ignition switch sticking) all thoughts appreciated

I haven’t changed them yet, but the car isn’t being driven. Currently removing plugs and coils to check or replace as necessary. Chain tensioners are next on the list before going back on the road. Looking around for parts and videos on how to. Thanks for the heads up, I had no idea this was such a danger before. Have done some reading on it and it’s definitely on the have to do list.

I have spent the last two hours searching around for timing chain tensioner parts and I have managed to confuse myself about exactly what I need and where I should buy them from. Would some of you experts please advise me what I should buy and who you would buy them from. I would be very appreciative.
2001 S type 4.0 85K miles

[QUOTE=NBCat;1937666]You can check with some of the forum sponsors by clicking on the Marketplace tab at the top of the page.

There are also some kits for sale on eBay:

https://www.ebay.com/itm/Timing-Chai...sid=m570.l1313

More importantly, follow the procedure in the Workshop Manual, which you can download here:

https://www.dropbox.com/home/Jaguar?...S-Type_FSM.pdf

You must also use the correct tools to properly time the AJ28 fitted to the S-Type:

https://www.ebay.com/itm/Jaguar-97-0...itleDesc=0%7C0[/QUO

Thanks very much for the leads. I have the tools in my cart on eBay.i have two other questions please,
my car has 85k miles on the engine. Do I need to replace all those components or just the tensioners. Sorry if the answer to this should be obvious but I’m an old big block Chevy guy and these engines are still pretty exotic to me
also the link to the workshop manual takes me to the Dropbox home page. I have a Dropbox account but it won’t take me to the file. Do I need an invite or permission of some kind?

thanks again for your assistance, it’s greatly appreciated.

Thanks to everyone for all this valuable information. Special thanks to NBCat for the links to the manual, tools needed, parts and engine course. I have been reading about the variable cam timing and how the cams function in this engine and it really is pretty exotic for an old big block Chevy guy who grew up in the 60s and early 70s muscle car era. This engine is really a piece of work and I mean that as a compliment. I have to check with my family banker, read wife, to see about the funding to get all the necessary parts, but I’m not going to drive the car until I get this resolved. I’m so glad my first indication of a problem wasn’t a cloud of smoke and metal grinding followed by a quick stop. It might be awhile before I’m done but I will let everyone know how this works out. Any other suggestions are of course welcome, but if not thanks again.

Bill M in VA

Thanks for your post. I ended up doing the same thing you did, changed to NGK plugs and all new COP. I had the same result, it now runs perfectly. I’m thinking one of the coils was dying because the plugs looked pretty good. Valve cover gaskets are fine for now, no signs of oil or even smudge anywhere. I haven’t bought the chain and tensioner kit yet. I’m still looking for some help with how much to replace, proper parts, etc just like you are. I may derfer this until winter time when I’m not getting out much and need a project. I’m driving the car very little until I get that done, just 5-10 miles every week or so to keep the battery up and circulate all the fluids. It stays in the garage for now.

Thanks for the post..... I changed all the plugs to NGK and replaced all the coils and it now runs perfectly. Just not driving it much due to the need to change out the cam chains and tensioners. That’s my winter project.

Hi there. Attempting the full chain replacement Friday. 60% torn down. Almost to the timing cover. John

Thanks for your reply. Good luck with the project. Please let me know how it goes and if you have any bumps in the road getting it done. I haven’t started yet, family issues and competing priorities as usual. Hope all goes well for you.