My throttle started occasionally hanging-open a few months ago, then of late, got progressively more and more hissy. I reviewed the TSB's Bob referenced in post #4 here:
https://www.jaguarforums.com/forum/x...96-xjr-107975/
I searched the internet and found the new, increased-rate return spring at the pleasingly low price below $3! I was less enthused to find shipping charges in excess of $15. Tried adding a few more bits and pieces I don't "need" but would be handy to have around - all of which would fit in the palm of your hand along with the spring....and shipping ballooned to $24! So I e-mailed Motorcarman to ask if he had one lying around or perhaps had a local source? He replied that I didn't really need a new spring and explained how he handled the complaint when X300's were still in-warranty and before anyone was aware of the new spring.


I took some pics as I executed the procedure and have attached them in the pdf. Post-modification test run was an unqualified success! Throttle reliably returns to idle, now.

 

I'll also add that the higher tension new R493 recall spring is about $6 from Jaguar and is still available. I don't know the part number off hand, but it is in the recall documentation.

https://www.jaguarforums.com/forum/x...recall-126057/

.

 

I just bought and installed one, the part # is NBB3131AB

I haven't driven it yet cuz I only have a temporary-use permit from the DMV (long story), but I was able to wind it around a full extra turn, might be too tight now but it started and idled fine, just haven't ventured onto the road.

It was $2.61, genuine Jag part, $5 for shipping from terry's

 

I have performed the spring mod to try and cure intermittent high idle.
I have a question about the line in the Mod PDF:
"Motorcarman: “You don't need a new spring. I just unwind the old spring a half turn with pliers and then go one EXTRA turn when installing it again. You will find that it is too long so kinda guess how much too long, pull it back off, snip it shorter and then install it.”

I wasn't paying enough attention when I removed the original to remember how many turns it was.
So do I wind the shortened spring 1 Full turn or 2 Full turns when I re-install ?
Thanks

 

He meant 2 turns total, but there are multiple stop points available, so experiment as needed. I did this for the interim while I wait for the new higher tension spring to arrive:

https://www.ebay.com/itm/JAGUAR-XJR-...M/161588956541

 

Rod, did you see the pdf?....there's pictures!

 

I have a high idle every now and then. In the past, I've taken the boot off the throttle body and sprayed carb cleaner in there. The throttle plate seems to get gummed up and stick. At least that's what I thought it was. Now I wonder if I need this spring. If my car has a high idle, I just put the car in neutral and tap the gas pedal and it settles down to a normal idle.
So is my problem the spring?
Was there a stronger spring replacement solution back in the 90's and is this one on Ebay the solution?

I wonder if the dealer would still take care of the recall, if it hasn't been done on my car? It's emission related, so they might.

 

I have a high idle every now and then. In the past, I've taken the boot off the throttle body and sprayed carb cleaner in there. The throttle plate seems to get gummed up and stick. At least that's what I thought it was. Now I wonder if I need this spring. If my car has a high idle, I just put the car in neutral and tap the gas pedal and it settles down to a normal idle.
So is my problem the spring?
Was there a stronger spring replacement solution back in the 90's and is this one on Ebay the solution?
UPDATE: I pulled my files on the car and the recall was performed in 2002. So I have the stronger spring. I guess the intermittent high idle is from gunk.

 

The ebay item is the updated (stronger spring) NBB3131AB , though I have yet to get it in my possession. It sounds like your 2002 spring has fatigued regardless. Even if it is gunk causing the stickiness, a stiffer return can often overcome that. Of course it is in your best interest to get it as clean as you safely can. It is also pretty easy to add more preload to the spring, so I would give that a shot (and order a new one too since they are only $6.95 shipped), and not try bothering a dealer with it if it hadn't been done yet.

 

There comes a point when a stiffer throttle spring will overcome a balky throttle but at the cost of an uncomfortable pedal pressure.
A balance must be maintained.

You might want to obtain a new replacement spring before you add extra windings and cut the surplus 'tail'.

I straighten the last half of the spring with pliers, cut a half turn off and then add one extra winding so it is actually just an EXTRA HALF TURN of the spring.

(I am a non-attorney spokesman, your mileage may vary, not responsible for lost or stolen articles left behind...................)

 

"There comes a point when a stiffer throttle spring will overcome a balky throttle but at the cost of an uncomfortable pedal pressure.
A balance must be maintained."

Exactly. Thus it is most prudent to clean completely first,

I haven't removed the throttle body from the intake on mine (not very dirty really), so I haven't removed the TPS. I noticed the replacements are pretty spendy, so is there potential to damage it with cleaning fluids in the throttle body, such as seeping down the throttle plate shaft? Should a proper clean up be to remove the throttle body AND the TPS prior to cleaning it all up?

 

I would clean it 'removed' and also take the TPS off, BUT I have several WDS and IDS/laptops so I can reset the TPS if it becomes necessary.
Many people don't have that luxury so it would be prudent to clean and dry inverted?(leave TPS in place)

That way it is less likely for solvents to contaminate the TPS?

bob

 

Update: I received the new spring, and went to install it. With the linkage tower off, the throttle actuation is smooth and full, with no stickiness at all. I then installed the linkage tower and discovered that it is the source of the closed throttle stickiness (requires a healthy pressure to 'pop' it loose), and the higher rpm stickiness as well. I then experimented by shifting it around a little in all directions without it being bolted down. It appears that it is not lining up perfectly with the plate shaft anymore and needs shifted a touch from where it originally sat. In order to do so, I had to drill out the mounting holes a little on the bracket. I didn't have a lot of time to fine tune the position, but it is much better now. Will have to have a closer look to figure out what is hanging up when in original position, and relieve the stickiness. Ideally it should be able to work with a light pedal and not require over loading the return spring.