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1998 XJR...I have noticed when on the highway, if I fully press the gas pedal, the car seems to not downshift and "take off" so to speak. On any other automatic that I have had, it would surely downshift and have a quick "getaway".
If I use the manual shifting mode on the J-gate and put it into 3rd and floor it, it is definitely much faster than if the car is in drive and floored. I have never put it in Sport mode, and don't think that I should have to put it into Sport mode in order for it to downshift and fly.
There's nothing wrong with the transmission, it upshifts normally and doesn't slip or anything. HOWEVER, the previous owner did state that the transmission had been replaced with a "less problematic" 2002 model. I have no idea if it actually was replaced or if he was trying to make it sound like work had been done to the car. I don't know what transmission is in the car or how to even tell.
Does not have any codes or service engine light. Vehicle has 120,000 miles. Not sure if there is an adjustment that needs to be made...maybe throttle cable? TPS?
Once you get your throttle cable adjusted, you can check to ensure the kickdown switch engages at the same time the throttle butterfly valve reaches its stop. The kickdown switch is under the accelerator pedal, Part 5 in this diagram:
I'm not sure of the setup on the X308, but on our late XJ40 the kickdown switch mounts on a threaded stud with a stop nut. You loosen the nut and rotate the switch to adjust its height until it engages at WOT, then retighten the nut to fix the switch in place.
Thank you for the link to the cable adjustment. I will play with it tomorrow if time permits.
Also, the diagram of the pedal...I see the switch, number 5. It looks like just a plastic pedal stop. I will have to take a better look tomorrow and see if there are any wires coming out of it or what the case is.
I had the same issue in my 98 until i adjusted the TB and kick down correctly. Night and day difference in acceleration. Before adjustment under the majority of pedal to the metal conditions the car would not downshift.
The early cars had the EGS51 TCM and will only kick down 1 gear the latter R cars have the EGS52 and will downshift 2 gears at once.
I had the same issue in my 98 until i adjusted the TB and kick down correctly. Night and day difference in acceleration. Before adjustment under the majority of pedal to the metal conditions the car would not downshift.
The early cars had the EGS51 TCM and will only kick down 1 gear the latter R cars have the EGS52 and will downshift 2 gears at once.
I believe I have that early model TCM because it seems like it may only be a 1 gear downshift. Can the latter model TCM be interchanged?
The kick down is much slower in normal mode: I find it more effective to pop it into 4th gear or punch the Sport button.
exactly!!! put it in sport. Ive told customers to do this for years. it gives a more agressive shift pattern and goes down 2 gears not one and shift point is 500rpm higher. very suefull if you pull in front of someone and need to get out of the way.
exactly!!! put it in sport. Ive told customers to do this for years. it gives a more agressive shift pattern and goes down 2 gears not one and shift point is 500rpm higher. very suefull if you pull in front of someone and need to get out of the way.
I will give it a try and see if there is a difference.
exactly!!! put it in sport. Ive told customers to do this for years. it gives a more agressive shift pattern and goes down 2 gears not one and shift point is 500rpm higher. very suefull if you pull in front of someone and need to get out of the way.
+1
In town, I am permanently in SPORT + 4
On the highway, it used to be SPORT + D.
Lately, it's been SPORT + 4 on the highway as well.
80MPH cruise is about 2500 rpm and there is no more
sag when going up a long incline.
I did it to get a feel for where the engine would cruise
and the gas mileage with a 3.58 diff.
I don't know of any one who had done it for jaguars tho the swap is possible in Merc's. Adam699 worked at it pretty hard and determined it could not be done practically. He elected to get a programmable TCM. Before you think about altering your system, adjust the pedal: i have zero complaints. I drove a 2002 R1 and and it did not feel any different then my 1998. as i said in my other post: night and day difference. my car preformed exactly as yours does before adjustment.
Well I adjusted my throttle cable and it didn't really need any adjusting honestly. There was hardly any slack in the cable and when I adjusted the square adjuster piece any more than 1/4 turn, the throttle plate wouldn't close fully. The part that the cable connects to never rested against the stop screw.
SO...waited for my buddy to get off of work and bring his scanner over. He is a mechanic - doesn't know a ton about Jags specifically, but he did say that he would be able to read throttle position with his scanner (which is a $6000 unit). Hooked it up, throttle read 5% when closed, which he said was OK. When the gas was fully depressed, the throttle only read 60%!!!! I adjusted the kickdown switch which seemed like forever. Turned it in and in and in...finally, the switch read 98% and I stopped there. Going for a test drive now.
Well the kickdown switch adjustment did the trick! I can actually hear the supercharger whine. Car is flying now...I sure hope so since it was only 60% open previously! Night and day difference: YES!
07-07-2015, 07:40 PM
Crappy Kickdown / Downshift ...Slow Get Up
