Over the last month, I have been targeting my ABS/traction control and have it fixed. But with that, of course, have brought along a few other issues that I need some help on. I purchased a new parts car with everything I need plus a lot more. (If you are looking for something let me know). I pulled off the traction control, all cables, and the throttle body. I cleaned up the throttle body and replaced the main spring,(the bottom one), and cleaned up the upper spring. Looks brand new now. I have the car idle set to about 600 RPM and for the most part, the car is running great.

I just drove about 250 miles and when letting off the gas the car starts to back down but VERY slowly and sometimes I have to hit the gas peddle real hard for it to continue to back down. While on cruise control going down a hill it lets up but again slowly. If I go to stop it will, of course, slow down and the idle begins to go down as it should. Also when passing I have to punch down hard to get it to drop down to the passing gear.

One thing that it might be is that when I put in the new spring I am not sure if I am supposed to just put it in with minimal tension or take it around a few times to make it tight. I tried to do that first but I had it so tight that it was hard to press the gas peddle and get up to speed.

Wondering if I should "RESET" the car after all the changes.

The new spring that I purchased was NEW JAGUAR SPRING NBB3131AA

Let me know what you think

Phil

 

Jaguar had info for this a few decades ago.

You might need to reset all the cables and check spring tensions?
I have had to add 'helper-spring' from an XJ40 throttle setup in extreme cases.

I also have had luck unwinding the old spring a half tun (bending open) and then a full turn more and 'snip-off' the longer 'tail' to seat the spring.

 

The idle is fine. Example would be driving at highway speeds. Staying at 75mph.you come up on another vehicle, let off the gas and nothing really happens. It is not that the throttle is stuck. Something is keeping it from slowing down immediately. If I hit the breaks it would slowly start to decelerate but very slowly. Also if I open the hood and pull on the throttle body and Rev the engine it goes back to idle speed fine.

 

I gave it one extra twist on the throttle spring and seems to help but it is a little harder to press down on the peddle.

 

One mistake I made when reassembling mine was I put the lever from the cruise control bellows to the throttle body on the wrong way, this caused it to bind a little when decelerating. It would take a few taps on the pedal to release properly. It's a simple enough setup, so hopefully something in there is misaligned.
Maybe try disconnecting the cruise control linkage to test it out.

 

It is funny you say that I was looking at it today and wondering does the throttle linkage go on top or on the bottom of the cruise control.

 

I hope you have the same problem, since it will be a 2 minute fix.
Here's a photo of the cruise control linkage on mine, which is working normally.

Cruise Control to Throttle Body linkage

 

Here is mine so I think everything looks correct. I took a bigger view just in case someone see something

 

The cruise control connections look ok from up there. The two arms should have a loose connection, with a good gap. There's also a washer on the nut.
It all looks like its hooked up as it should be from what I can see.

 

I don't know why, but if you did clean the butterfly when you had the throttle body out (and you clearly did) then a TPS reset is in order. I don't know why, but it does help.

The only other issue I can think of is whether the TPS is properly seated? Maybe too tight, not tight enough? I believe the TPS is also spring loaded, is it not?

 

TPS reset? Is that a dealer thing?

 

I am beginning to think I live in a third-world country. So I called the local, and only, Jaguar dealership and told them I needed to bring in my car to get the TPS reset. The answer was, "The scan tool for that sometimes works and sometimes doesn't. We will give it a shot but Jaguar does not support "old" cars anymore and if it does work may not be able to reset it." I guess I have no other choice. That also tells me they probably don't have anyone that works on "older" jaguars. I will continue to look for someone that might have a scan tool to work on it.

 

Although there is little to no wiggle room on the TPS, you should be able to 'adjust' it so that you see the right voltage on the sensor at idle.I should be 0.6 volts, oh and you'll need a multimeter.
If all you did was remove it and clean the TB, then you should be able to return the TPS to it's original position.

Check the link here.
https://www.jaguarforums.com/forum/x...y-free-164263/

I don't have IDS or WDS systems, but I believe they can do the TPS reset as well as other things like O2 sensor re-orientation.

 

Well I will give the dealer one shot. Hand them the directions to set it and if that does not work I will do it myself

 

I followed the procedure and I went from. 2 to. 6. Will see how she rides.

Update.....SOOO much better. Thanks for all the advice as usual. Everything is working better than it was.

 

Awesome news, well done. And a cost free fix.
Are you able to check ODB2 fuel trims? It might be interesting to see how it's settling back in to normal running.

 

Everyone uses acronyms on this forum, is there a list I can use to translate please? First off would be TPS?

 

Throttle Position Sensor (TPS)

 

I am out of town and only have my Autel with me, and not sure I can use that, but when I get home, I will check. It was interesting after the fix. Idle went real high and stayed there for a few. I shut the engine off to clear all my codes from the change, started it back, and it came right back to 650-700 RPM. If there is a way to check it with the Autel let me know and I have time to review.

 

I don't know the Autel, but I assume you should be able to check long and short fuel trims.
it's probably not urgent, just good to know.