So, I have been having some issues with my kick down lately where it doesn't kick down nearly as much as it use to...

One person suggested adjusting the button on the floor by turning clockwise to increase and anti-clockwise to decrease, one problem, I can turn it anti-clockwise but it will not budge in the other direction..

Is there some special procedure that one must do to turn it clockwise?


Thanks all!

 

The throttle stop is screwed onto a unique looking bolt, have you tried pressing and pulling while attempting to turn the stop, it might be bound or x-threaded.

Also have a look at your throttle cable adjustment, to set it up remove the cable tie and give it a couple of turns to tension it then replace the cable tie. By checking throttle open % look at your obd scanner, I've always set them at 99% when the pedal is on the stop (100% can trigger a failsafe mode).

hope that helps

 

I did attempt to push and pull it whilst trying to turn it. I may not have been doing it correctly, I was in a bit of a rush. I turned anti-clockwise two clicks just fine though!

 

Does the ZF tranny have a kick down button at all? I've been searching and haven't found a thing... And my kick down works!?

 

I am not sure if the tranny itself does or not, but there is the sport button as well as the button on the floor by the accelerator petal. The kick down works, but it doesn't seem to go down as much as it use to.. Not sure the cause. It does have the same power/acceleration.

 

There is a stop-nut on the threaded shaft of the kickdown switch that you would need to thread up the shaft a bit in order to turn the switch further clockwise, but Sean's suggestion to adjust the slack out of your throttle cable is what I would do first, since cable stretch is the most likely cause of kickdown issues.

Once your throttle cable is properly adjusted, you can check the kickdown switch adjustment either by following the instructions in the Workshop Manual (using the PDU or equivalent), or do it the shade-tree way by setting it so the switch connects just as the throttle reaches its WOT stop, then hold the switch in position while you tighten the stop nut downward against the floor.

Cheers,

Don

 

Awesome, I will go ahead and give that a try when I get the car back from the body shop!

 

FYI - XJ8's have a floor stop, no kickdown switch, kickdown is taken from throttle position the ECU requests a lower gear from the TCU, hence getting the cable set up correctly.

The XJR's have a kickdown switch and this is direct to the TCU, I think....Both models benefit from correct throttle setting, in some cases down to 70%, when back to factory spec' owners comment that it's like having a new car.

My advice if the throttle position is down via OBD would be to set it up to as close to 99% then perform a hard reset and then let the car idle for 10 minutes to store the new throttle settings. This added to a new air filter should see better economy along with added performance.

Hope this helps

 

So, from what it sounds like, I will want to wait to set the throttle cable until I put on the new air filter & air duct? Not sure if it will make a HUGE difference but even if it is minimal I would like the car to run at peak efficiency & power. Hehe

On a side note, since I drive (almost) like Mario Andretti I want to do a trans flush, but don't know the history of the trans.... Can I replace the filter without draining the trans?

 

Hi Sean,

Before I advised Bcrary3 in my earlier post, I checked the EPC to confirm that his car should have a kickdown switch. The EPC lists part numbers for kickdown switches for both the Supercharged and "Except Supercharged" cars. Here are the numbers:

4.0 Litre Supercharged:
To VIN 853935: LNA6570AC
From VIN 853936: LJC6570BA

Except 4.0 Litre Supercharged:
To VIN 812316: LNA6570AC
VIN 812317 to 853935: DBC10854
From VIN 853936: LJC6570AA

The retail prices given for all the switches are similar (74-78 (pounds?)). I just searched all five of the above part numbers at jaguarmerriamparts.com, a U.S. Jaguar dealer, and all the parts show up as "Switch-Kickdown," and all are listed at discounted prices of about USD $29.00. You would think that if the units for the N/A cars were just a stop, they would be less expensive than the units for the S/C cars?

Could it be that N/A cars in certain markets have stops instead of switches? Or are the parts listed in the catalog as kickdown switches actually just stops?

Any clarification you can offer would be appreciated.

Cheers,

Don

 

To change the filter you have to remove the pan, so of course you must drain it.

While you have the pan off, remove the forward valve body and install the upgraded main pressure valve from ZF or the alternate from Transgo.


http://jagrepair.com/images/AutoRepa...%20ZF5HP24.pdf

ZF 5HP24 TRANSMISSION PRESSURE REGULATOR VALVE KIT TRANSGO 5HP-24-PR FITS BMW A5S440Z JAGUAR AUDI ROVER - The American Powertrain Warehouse

 

Sean's comments about the kickdown switch made me curious, so I just spent some time with the X308 Electrical Guides, and it appears that all of the S/C X308s have a kickdown switch, but only the early N/A cars with the AJ26 engine have a kickdown switch.

The later N/A AJ26 cars and all AJ27 N/A cars do not have a kickdown switch.

This still leaves me curious about all those part numbers for "Switch-Kickdown" in the catalog....

Cheers,

Don

 

I'm surprised they have an actual (connected) switch as for many years the same function has been done by software, with at most a dummy switch (so it "feels right").

 

Cheers for this information! I thought there wasn't a switch down there as my kickdown would also engage with a good gas blip without pressing right down...