XJ XJ8 / XJR ( X308 ) 1997 - 2003

Foot hard down... but nothing happens.

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Old 01-03-2016, 06:15 PM
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Angry Foot hard down... but nothing happens.

I've gone 3 months without this bothering me, but after being rinsed at the lights by my female colleagues Peugeot 206 I feel I need to take some action!

I've got a 3.2 '99 XJ8 Sport (99k miles) - if I put my foot to the floor doing around 50mph, the acceleration throws me back into my seat (love it)

If I'm at a standstill, or doing less than 40 mph - flooring it seems to put the car in neutral (the best way I can describe it). Lifting my foot off puts it in gear, but there is no urgency in the acceleration.

I have lurked in the past and read about dodgy fuel pumps, but I can't tell if these people are experiencing the same problem as me.

I hope someone might be able to shed some light on the issue!
 
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Old 01-03-2016, 07:20 PM
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That sounds more like a transmission problem. It should downshift when floored. But I don't know which transmission is used in the 3.2 sport.
 
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Old 01-03-2016, 07:45 PM
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Did you notice what your engine rpm was doing? That would tell you if it's a gear box issue.
 
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Old 01-03-2016, 08:20 PM
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Does pressing the sport button not help?
 
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Old 01-04-2016, 02:16 AM
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I have a faulty MAF sensor and a similar thing happens... but it's at all speeds, not specific ones. Probably not the same problem you have, but might be useful if you're having trouble finding the exact cause.

Are you getting any fault codes? That would be the first place to check if you're getting a sensor error
 
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Old 01-04-2016, 05:44 AM
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You might want to check the throttle cable for excess play. At idle the slack will effect the throttle response above that the slack is out of the cable and the throttle responds. It is easily adjustable at the throttle body connection.
 
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Old 01-04-2016, 01:39 PM
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Originally Posted by themechanicco
Did you notice what your engine rpm was doing? That would tell you if it's a gear box issue.
It sounds like the revs climb, but I'll have to double check - what rpm's would suggest a gearbox problem?

Originally Posted by Wessex
Does pressing the sport button not help?
It makes it worse unfortunately! I can take off faster without the sport button - if I need to drop a couple of gears at 50mph the sport button does it job though.

Originally Posted by grandell
I have a faulty MAF sensor and a similar thing happens... but it's at all speeds, not specific ones. Probably not the same problem you have, but might be useful if you're having trouble finding the exact cause.

Are you getting any fault codes? That would be the first place to check if you're getting a sensor error
I'll put this on my list of 'to-checks' - I'm a complete novice though, what do I need to get the codes?

Thank you for all the feedback so far!
 
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Old 01-04-2016, 02:01 PM
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Originally Posted by Stenzi
It sounds like the revs climb, but I'll have to double check - what rpm's would suggest a gearbox problem?



It makes it worse unfortunately! I can take off faster without the sport button - if I need to drop a couple of gears at 50mph the sport button does it job though.



I'll put this on my list of 'to-checks' - I'm a complete novice though, what do I need to get the codes?

Thank you for all the feedback so far!
If your car seems to rev quite a bit for the relative speed, you may have clutches slipping.

If you have a check engine light you can use a code reader to get the code and then look it up. Some codes are Jaguar specific so you'll take the code and look it up here:

https://www.jaguarforums.com/forum/x...d-codes-45032/

Here is a copy of the procedure that should work for your car to adjust the throttle cable. You just have to remove that cover near the firewall that exists on the XJ (not on the XK). If you have a scan tool, you can read the value for the throttle position sensor and verify you tightened it to 100% there too! This procedure is more than enough though.

https://www.jaguarforums.com/forum/x...e3/#post220085

Originally Posted by hlgeorge
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.
 
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Old 01-05-2016, 03:15 AM
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Blocked cat(s) might be a cause.
 
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