Where do I look for the throttle return spring on my '03 XK8? The amount of foot pressure required on the accelerator pedal to control ones cruising speed or ones rate of acceleration seems excessive. I think it detracts from the drivers smoothness and overall driving pleasure. Fixing that problem before drive by wire became the norm was easy. Long short. Where is the the return spring on the electronic throttle controller located?
RB

 

Probably SNG Barrett (one of the sponsors here) can help you out. Funny thing is that with my 2005 XKR I feel the pedal can use MORE pressure (heavier spring). The perfect feel for whatever car I have owned is when you can be cruising around at highway speeds and basically have your foot comfortably resting on the pedal. With my car I feel I have to hold back a bit which produces leg fatigue. At constant open highway cruising this would not be an issue since I could just engage the cruise control. But around LA the freeways are generally not consistently open enough to do so, hence the leg fatigue.

Doug

 

If throttle by wire, buy a Sprint Booster.

 

Number 3 on the below is part number MJA4715BB priced at around $35.00 with your discount.. Hopefully this is what you're searching for?

 

I have the same problem with both of my cars. I suspect EH may have some other problem, like a binding bushing. Of course, mine aren't drive by wire so it's not the same thing.

 

All XK8s are are sort of a semi-drive-by-wire design.

There still is a mechanical linkage to the throttle body, to a position sensor.

The actual throttle is moved by a servo motor in the throttle body, within mechanical limits for safety in the event of electrical fault.

See http://www.thejagwrangler.com/upload...c_throttle.pdf for the details.

 

That's it (#3 in the parts drawing). So the question is, how do I decrease the amount of spring tension the spring exerts on the pedal assembly without pulling the entire assembly apart and cutting a coil off the spring? There isn't a ton of room down there for big hands to easily pop the two C-Clamps to get the spring off. Looks like I'm stuck using a heavy foot .
RB

 

You might also check your throttle cable. Usually it is too loose from age, but maybe yours has been adjusted too tight. It should have a slight amount of slack in it when pushed in the center point of its length. No more than maybe 1/4", but it should not be so tight that it has no slack at all.

Also check your butterfly to make sure it is not sticking. Crud builds up into a ring around it and it might be sticking slightly and opening up only after you have used too much pedal.

Both easy to check and easy to adjust. It might help and can't hurt.

 

Thanks Mike. All adjustments from the pedal to the TB are in spec. My initial complaint was and continues to be that the amount of spring tension at the pedal arm seems more aggressive than my foot is used to. Nothing is binding, needs adjustment or needs to be lubricated. The entire assembly all the way from the pedal to the TB is working just the way it was engineered. Perhaps I'm just too picky with the Jag but the foot pressure needed on the throttle pedal of my other cars (including three non throttle by wire mussel cars) just 'feels' better. I could be suffering from the 'Goldilocks syndrome' and can't quite say, "this one's just right".
RB

 

Try to shorten the arm on the spring (where the 3 Points at) and "recurve" it around the pedal leaver (no 9). This way the spring will seem weaker.