I bought a 01 XJ sport for my wife while in a pinch, and fell in love with it the more I worked on it, and I have worked on it a lot! One thing that has baffled me from the start though, is having overdrive only half the time. Like clockwork, every other start will have overdrive, and the every other, will give no attempt what so ever to make the shift. I've taught her to look for the rpms being higher than they are supposed to, and turn off the vehicle for a few seconds, and turn back the key and instantly regain overdrive.
I've changed the transmission solonoids, filter, and fluid with a Lucas additive, and installed a new TPS all with no effect on this issue. My best guess at this point, is some sort of malfunction with the pcm, but was hoping one of you might be able to point me in another direction before I went to that expense. Thanks

 

look at cruiser54's website in my sig below, and do the procedure for refreshing all the transmission connectors (if you haven't already), then check the ground on the engine block right below the oil dipstick (where your tranny grounds). Then see if you can find a used TCM (the transmission control unit located under the drivers side dash, above the gas pedal.) my junkyard charged me like $10 for one. You may not need a new computer, just a new TCM. Let us know how it goes!

 

I appreciate the input, I had no idea the transmission had it's own computer. I was going to track down the grounds this weekend anyway, so I'll be sure to check that transmission ground. I found a tcm on ebay for $40, so I'll plug that in as soon as I get it, and post my findings.

Thanks again.

 

Soooo, today I did the 4 hole injector swap to have the upgrade, and having narrowed a long crank issue to the injectors, as I've already replaced the fuel pump assembly. After installation I reset the pcm, took it out for a test drive, and had overdrive. I thought this was strange, as it would have been the "other" start, and I shouldn't have that gear. Intrigued, I turned off the vehicle, started and got overdrive once again. After 5 times testing it out, I'm willing to say my overdrive issue is fixed. Now I'll see if I can return the TCM, or I'll just hang onto it, in case I ever need it.

Long story short, if you have overdrive every other start up, reset your PCM.