I cannot emphasize how simple a check for good operation can be. I'm old enough to remember having to re-pack the front wheel bearings once yearly to maintain the ability to steer, then replace the cotter key to prevent loosening. Jack it up, put hands at 12 and 6 and rock. The wheels on a 1956 Chevrolet would wobble maybe 1/8-3/16 when properly adjusted. This was important as the brake shoes would sometimes overheat and cause splaying of the wheels, if too loose. Now, if only I could adjust the vacuum advance with a spring on the distributor again. NOT! I don't miss cable brakes, either, even though my '36 Ford Pickup is so equipped. You measure stopping distance in yards, not feet and inches. Thank you to OP for your insight.

 

Greetings Fellow Jag Junkies,

Had almost every problem Razorboy listed below, with my 03 XKR.

Gear Ratio Faults
Transmission output faults
Weird shifts between gears
2nd to 1st gear bump
RPM flaring between 3-4-5 shifts

Plus:
Howls on shifts
Restricted Performance, etc

Thought for sure I needed a new tranny. Then started thinking about the intake I had cobbled together from Silicon Intakes a few years ago to save on an OE Jag Intake pipe. It looked OK, but as I found out, was leaking like a sieve. Not to mention disturbed air flow.

Got the Mina intake installed and it's like I have a new car. Smooth shifts, no codes and feels like 50 extra HP.

With tranny probs, I highly recommend checking the basics first: coils, plugs, ignition, intake etc. These cars are so sensitive to incorrect pressures and temps. Try the little things first. You may be pleasantly surprised.

ET

 

Congrats on the fix! Who'd have thunk that would be the fix when you weren't throwing any lean codes. Yeh - the Mina set-up certainly reduces a bunch of variables. It's amazing how finicky these cars can be when seemingly unrelated functions are amiss. All of my tranny and cruise control problems were due to worn rear wheel bearings! I was very diligent to keep all the splits in my intake's bellows nicely sealed, so I stayed OEM throughout. I did like the "tuning" it provided. Congrats again and thanks for sharing! (You never know who might now be able to stop tearing his hair out - lol)

 

Would've been very interesting to have seen the fuel trims before the fix. (And whether even running closed loop.)