Well the big cat is out of her winter slumber (with a few short sleep walking episodes to keep fluids free and moving) and as I've been driving her around I'll find myself looking down at the console to see if I've accidentally hit the "sport" switch. I use that one sparingly as the old girl is pretty lively without hitting it and although great fun I can watch the gas guage dive for E as another tank full of 93 octane releases all that energy the dinosaurs left all those millions of years ago.
Acceleration lately has been pretty exhillerating as the big cat practically leaps in response to the go pedal and each time I look the "sport" button is relaxing in wait mode. I was thinking back to one of the "dry day" winter drives that my wife took, a nice highway blast to work and back that allows everything to get up to temperature, this past February. She called from work and was very shaken up as going around a left turn at the bottom of the exit ramp near her office she lost control, over steered, over corrected, spun (missed everything), and came to rest pointing the wrong way.
I chalked it up to a little ice on the road and my wife's lack of drifting practice but given my recent observations I'm wondering if these are signs that the throttle body doesn't know where it wants to position the throttle plate.
Starting is fine, idle is fine, cruising seems ok with no noticable surging but something seems different from previous years use. Has anyone recently had their XJR throttle body rebuilt or replaced? If there's any recommendations for sources or suppliers it would be great to hear what you've got.
Thanks.

 

from my experience, sport mode is more so just for transmission programming and eagerness to downshift. It would be an odd failure to have the throttle be more touchy after sitting over winter. I don't think there is anything wrong with your throttle body and sources for rebuilds are pretty slim from what I understand. You could always try a used throttlebody off ebay or something if you're convinced its a problem.

My advice would be to simply adjust the throttle cable so there is a bit more slack at tip in. Might just take a half turn.

 

I'm pretty sure the sport button does affect the sensitivity of the throttle as well as the gearbox. I've never heard of one doing such things on it's own though.

 

Yes, I am with Quadcammer on this. It is much more likely the Mrs. ran into a slippery spot of oil, wet pavement,
or maybe ice as you suggested, than a throttle body issue. These cars are usually pretty good about taking corners.

 

That was my initial take about the spin the little woman took but my recent observations have me wondering.
As for what sport mode does (uses 1st gear for starts, holds shifts longer, or what other magic) it sure does make a difference when engaged (acceleration and thirst for fuel).
I just replaced the throttle body on our manvan but it had been exhibiting several symptoms, irregular idle, dead spot just off the line then surging ahead, as well as surging at my popular highway speed.
All this pointed (to me anyway) to the throttle position sensor being worn at the popular spots.
That could have been either sensor (pedal or throttle body) but the pedal lives in a pretty cushy environment compared to the throttle body.
Despite skeptisism on the manvan board all the symptoms disappeared and the big lug behaves much closer to what it's being told aftre the switch.
As far as the Jag it could be my mind playing tricks on me (I'm not as young as I used to be) but I think it's a change in behavior.
I guess I'll monitor it while I search for a good used throttle body...

 

https://www.ebay.com/itm/16595369396...Bk9SR-qamfLzYQ

https://www.ebay.com/itm/27547168234...Bk9SR-yamfLzYQ

 

I think I have the answer for your question.

3 years ago my X308 developed the issue the car just kept installing even when running ( I know it sounds crazy) . I sent my TB for rebuild service. see the link. I think they are also on eBay.

https://www.autoecu.com/jaguar-3/

I went extra step sending the "just rebuilt"_TB to another place for porting.

my suggestion, don't just buy another "used" TB for replacement, it may work for now but they are just as old as the one you have. just a matter of time, the used one will die also putting you in the bad situation.

now I have my peace of mind .

 

https://socalporting.com/

they ported my TB

 

I have a slightly used TB off a '98 XJR that's been in a plastic bag for 19+1/4 years. I had to replace the TB about a month before I crashed the car, and I rescued it the day after.
PM me if you're interested in a spare.

 

Thanks Vincent, what did the porting cost you and did you think it was worthwhile?
Thanks Quadcammer for the ebay links, it will probably make sense to get ahold of a spare that I can use while mine is being repaired.

 

these cars are always dumber than a rock in winter mode that’s just how it is. when you press the summer button you’re starting in first you get double kickdown all that fun stuff

throttle isn’t your problem

 

I did the porting pre/early-COVID in 2020 as well and the rebuild . as you know about the COVID inflation. I don't remember the exact price for the porting but I recalled it wasn't that much and sounded fair to me. But let me say 2 things up front here for declaimer. even the shop was being transparent to me saying there was too much metal they can shred out but the difference is notable. it is worth the price I sent.

back to the TB rebuild . Also my suggestion. DO IT anyway even TB is not the root cause today but it will be your headache one day soon. if you need to drive Jag and dont have the way to store the disable car. you want to get a back up TB.

 

Found the picture

 

???? pull the throttle motor connector and the limp home lever will take you to where you need to go

 

Vincent, is that TB ported on the underside as well?

 

Edit, my mistake ;-)

 

Yes