The 4.0 engine is a little different to adjust and easier it may seem. (Mine is the R model, but I assume the standard is similar)

The location of the cable and adjustment is not under the small cover, but attached to the left side of the throttle body.


Now you can pull back on the throttle by using your thumb on the post on the outside throttle pulley. When you let go, you should hear the metal to metal contact of the pulley as it snaps back into idle position. This is important to remember. There is a cable strap holding the throttle cable in the cable bracket. Clip the cable strap and remove it. (Be sure you have a replacement handy.) You can grab the throttle cable with two fingers and lift it up and down to see if there is slack in the cable. Now, grab the throttle cable on each side of the bracket with two fingers and lift straight up. Notice that the cable sheath is like a screw and the bracket attachment is like a nut on a screw. Turn the bracket attachment a few turns so that the cable goes to the rear of the car and snap it back in place. Feel the tension on the cable. Pull the throttle back with the outside pulley and let it go. If you hear the metal to metal contact when you release the the pulley the cable is not too tight. You may want to over adjust the cable and move the cable back by 1/4 turn of the bracket attachment until you hear the metal to metal contact when the pulley is released.


Here is my cable adjusted and the cable tie reinstalled. I didn't have a black one handy, so I used a white one. If this bugs me later on, I'll replace the white one with a black one.


WHAT I HAVE NOTICED:
The accelerator pedal is instant. (No more tapping on it to the beat of the music!)

Now I understand the the reason behind starting off in 2nd gear on the R model. I do not have to press as far to get the car up to speed.
In sport mode, the throttle response is instant!

Downshifts seem to be quicker, probably because I am not pressing the pedal as far to get the car going.

On hard acceleration the car seemed to run out of torque in the upper rpm range, but now it feels like it is pulling hard until the throttle is released.

I have not had it on the freeway yet, so more to report later.

 

This is the best thread EVER!

 

By the way, the impression that correctly setting the cable to remove slack has somehow resulted in more power is an illusion. If the cable was too slack and the throttle blades were not fully opening, then the only instance where you will truly find more power is at WOT--otherwise, no difference.

If you want to see what I mean you can create the same illusion of more power by moving your seat forward a few inches from where you normally have it. I have played around doing this with past cars and the sudden responsive you feel makes it seem like you found a bunch more horsepower. In reality, you are merely putting your foot into it quicker. This will eventually go away as your body adjusts to the new position. Similarly, move the seat further back than normal and it will feel like the car is suddenly sluggish.

So when taking the slack out of the cable, the same power is there as before but it is now just more responsive.

Doug

Doug

 

I totally agree! But with proper adjustment you don't feel like you are having to stomp the pedal every time you accelerate. It feels more normal now. And WOT is more responsive and doesn't feel like there is a brick under the pedal. BTW, my seat stays completely back as far as it can go. Also did not find that the pedal moved at all inside the car. It is in the same position as it was before the adjustment.

 

Thanks for contributing Lew, I was hoping a 4.0 owner would give some good instructions for that adjustment.

 

I disagree. If the throttle was never opening fully due to a slack cable, adjusting the cable so it opens completely will result in more power. I definitely have more power at WOT, of that I am certain. Isn't that the only time your power really shows? But now I don't have any slack in my throttle cable. Where I used to be able to slowly press down on the gas pedal for smooth acceleration, I'm finding that now as soon as I barely move the gas pedal the car jumps forward. I put about 350 miles on the car on Saturday. If it was just a matter of me needing to get used to the tension in the cable, I think I would have gotten used to it already. I realize that doesn't mean I have more power on the bottom end of the throttle setting, it just means that the throttle is more sensitive.

I actually think the sensitivity at the low end may be because the throttle sensor isn't hitting the stop at the low end. Perhaps it's sitting at 10% open even at idle. The ECU is adjusting the throttle opening for idle, but then as soon as I touch the gas pedal the ECU sees that the throttle should now be at 20% rather than 0% and it opens the throttle to 20% causing that jump. As an example of what I'm talking about, sit in any modern car and try to rev the engine to 1500 RPMs and hold it there. It will go there for a few seconds, then it slows back down to the normal idle speed. You have to keep tweaking the gas pedal to try to hold it at 1500 RPMs. I'm pretty sure that's the cars ECU (or whatever it's called in that brand of car) trying to compensate for a driver who is resting their foot on the gas pedal at idle.

 

That is what he said so you agree LOL


Absolutely because you have changed thge "Tip In" on the car which is how sensitive the pedal is. As you stated smaller engined cars often change the tip in to give the immediate aceleration feeling while luxury cars tend to make a change in it so you have to depress the pedal more to accelerate the car to provide smoother starts and less neck jarring movements when you are in stop and go traffic or just accelerating from a stop.

 

I think we are all really just saying the same thing here. Just different interpretations of it.

 

I am a very non-technical guy - BUT - I have always heard that these cars "adjust and learn" from their drivers. Could that be what we have here?

Perhaps is is not so much the mechanical adjustment of taking out the slack, but the driver action of lowering the gas pedal to the floor (WOT) position, that is showing the increase in performance?

Inscrutable - these English! Dale D

 

Hey Everyone,

Would this procedure also apply to the X350 XJ as well?

Thanks,

Mat

 

I think the XJ is similar in many ways, so probably. Yours is a 2004, so I'd guess you'd have the new type of throttle position sensor, like on the video. Just pop the hood and take a look. It should be pretty easy to find.

 

All Right!!! The Tri-fecta!

Increased performance (or responsiveness?), nice 50's Ford V8 sounds, and new softer, grippier rubber! What's more to ask? If the mileage also increases - can the grin get any wider?

I'll let you know! DaleD

 

Actually, I have found that moving the seat forward gives that sense of more responsiveness because when you do that, you tend to put your heel farther up under the gas pedal, so that, in essence you do not have to extend your foot as far to give it the gas. When your heel is far back from the pedal, and you have to stretch your foot way out to give it some gas, it just feels exactly like that, that you have to really extend yourself, and your car to get it really going. Just put your heel up under and closer to the pedal, and you will get the impression that your car is suddenly more responsive. I found out about this when I bought a Mitsubishi, and I read info about it, where Mitsubishi had decided to make the car more responsive, and seemingly faster, by adjusting the gas pedal so that it applied a more open throttle faster than they had been doing it before. Even when you became used to it, it felt very responsive. When someone would drive it for the first time, they always started out from stop VERY rapidly, sometimes to the extent of spinning the tires slightly.

 

Wow I cannot believe something so simple could make such a difference.Ive not done it yet,but this weekend Im all over it.I will post with my comments then.Thankyou all for your comments.

 

Sam already answered, but just to add, the X350 (2004+ XJ) is the same engine/drivetrain as the 2003+ XK, so it should be just the same as Sam has documented here. My 1999 XJR is like the other pictures as it doesn't have the electronic throttle body that your model does, but the net result is the same.

 

Quote:

Originally Posted by Kevin D

Actually, I have found that moving the seat forward gives that sense of more responsiveness because when you do that, you tend to put your heel farther up under the gas pedal, so that, in essence you do not have to extend your foot as far to give it the gas. When your heel is far back from the pedal, and you have to stretch your foot way out to give it some gas, it just feels exactly like that, that you have to really extend yourself, and your car to get it really going. Just put your heel up under and closer to the pedal, and you will get the impression that your car is suddenly more responsive. I found out about this when I bought a Mitsubishi, and I read info about it, where Mitsubishi had decided to make the car more responsive, and seemingly faster, by adjusting the gas pedal so that it applied a more open throttle faster than they had been doing it before. Even when you became used to it, it felt very responsive. When someone would drive it for the first time, they always started out from stop VERY rapidly, sometimes to the extent of spinning the tires slightly.

By the time I get my 6'3" frame and my big feet into this cabin, there is very little room to consider pedal height, or foot access. I just know "it" goes better with this adjustment! DaleD

 

I took a look under the hood in the location where it would be on the 4.2 XK but I couldn't find the assembly. Does anyone have any idea where it might be?

Thanks,

Mat

 

Did you look at the video on page one? Unless you're driving a right hand drive car, it has to be under that little panel right there by the back left corner of the engine bay.

 

Just checked my 03 K8. Guess what!!! loose as a goose. adj it and seems like upgrade to an R. Thank for the post.

 

Matt, it appears your 04XJ8 has a similar accelerator arrangement between the pedal and throttle body sd the S-types; it remains different than the XK8/R and the <2003 XJs. You don't have any type of cable adjustment. This is from one of their threads.

I looked in the JTIS, in the same section as ours where it describes the adjustment procedure, and it wasn't in there...just like the s-type model. Sorry to get you excited.