maybe you should think about fixing it like widing the throttle return spring tighter since this was a problem and eventually a recall for sticking thottles via return spring weakness. the springs and kits are no longer avail, but all I used to do anyway was to remove the top of the throttle apart to get att he spring and wind it one turn tighter and reassemble. If your throttle was dirty before and had a differant IACS setting(idle air control solenoid) the ecu will drive it open more and result in a high idle. You probobly never needed a TB anyway, but since you replaced it work with what you have.. This is a 1st stage diag and repair, report back

 

Hello;

First thing to do for high idle is clean the throttle body. On the AJ16 there is no adjustment, it is all electronic. Second look at your Idle Speed Control Valve mounted on the throttle body and clean thetip as well. Remove the entire throttle body when cleaning and remove the Throttle possition sensor in the bottom. If you get any cleaner on it it will be ruined. Drive it a couple of days and see if the idle becomes normal.

At that point you might want to tri another Idle Speed Control Valve and see if that works

Good Luck

 

I am having the same issue on my 1996 xjs. I put the car in the shop and they came back with it needing a idle control valve solenoid or something to that affect. The part is 800 bucks direct from the U.K.. I should hear back about my car tomorrow and I will re-post if this corrected the problem or if further diagnosis is required.

 

I had the same problem with my 96es when I bought them. The first one was resolved with a throttle body cleaning.

After that car was destroyed, my second 96 needed its parameters reset by the Jaguar PDU. Never had a problem since.

My recommendation is to find a shop that still has a PDU. I was charged $150 total.

I can recommend one in Northern Virginia, but that may not be convenient for you.

 

A couple of things here:

-The part number for the idle speed control valve or steeper for our (95-96) cars is JLM12185.
-The part, directly from Jaguar in the United Kingdom, cost 152.00 pounds sterling which equals 230.00 US dollars plus shipping
-The part, directly from US vendors costs around 300.00 and is readily available
-Changing the part takes 10 minutes or less
-This job should be no more than 400.00 and thats assuming they will charge you 100.00 for one hour of labor, which is the 10 minutes to remove the part...if they are quoting you 800.00 for the part or for the part and labor, I would suggest immediately picking up your car from that shop and finding another, unless they meant that the price included additional items not mentioned .
I agree with Vee as far as having the parameters reset-its always a good idea on the AJ16 cars, as they seem to stray of from time to time.