XJGirl23

Back story:

This issue started very suddenly, and progressed very quickly. Initially, it was just a "hiccup" while driving on the highway, just a little bump every so often like it was slipping out of 4th. She's an '87 on her original transmission with 177k, so I assumed I would just need a transmission soon, no biggie.

Within a week it was significantly worse. Basically undrivable on the highway, because the whole vehicle shudders as it "slips" from 4th. Did the "slipping" more often than it didn't. For a while, it was just on the highway, and only in 4th, so I drove it around town in 3rd. Even on the highway, it was only after 30 min. or so, when the vehicle was fully warmed up.

Now, maybe 400 miles later, I cannot even drive it around town, as it's lurching and unable to "find" a gear (just describing the feeling, it's probably not actually what's happening) just three minutes down the road. It's hard to explain, but it's not just a slight "slip"....the entire vehicle is lurching and feels like something is about to break off.

What could it be? Could the transmission degrade so quickly (it's literally worse every time I start up the vehicle) and lose so many gears so quickly? (She does the lurching even in 1-2 now.) Throttle position sensor was an idea tossed out, so we replaced it and it hasn't seemed to help. Ignition coil was the next option, as clearly something is not happy about the vehicle warming up.

Any other ideas? Anyone had the same issue and fixed it with a $5 part from Autozone? At this point we're really not under the impression that it's the transmission, because initially the lurching could be stopped just by downshifting, but it's now "infected" all the other gears.

Additionally, she seems to have trouble starting forward when stopped for extended periods, as at a stoplight. The only way I can describe it is that something seems to not be connecting correctly, and there is a "grinding" feeling while everything "aligns" and then everything clicks into place and the vehicle can lurch forward.

Everything underneath seems to be in decent shape/where it's supposed to be, it's been gone over a couple of times since the problem started.

Thanks in advance!

excess650

PM me your email address and I'll reply back with the AW4 trans and troubleshooting manuals.

There are several items that communicate and control the shifting. The TCU is the controller. It receives input for the TPS (which must be adjusted on the older XJs) the VSS which is on the tailhousing of the trans, and the brake pedal switch which will disable lockup. There is also the kickdown cable attached to the throttle linkage, but is connected internally to the trans rather than electronically.

Has the fluid been changed? Did it look and smell OK? Has the filter been cleaned or changed? Do you have the correct fluid and the proper amount?

The transmission really is a "biggie". The AW4s quite often outlast the engines, so is pretty robust.

tjwalker

excess650 has you covered. Follow his lead as the factory service manual outlines some good troubleshooting tests.

You can disconnect the TCU and see if the transmission shifts normally (manually). If it shifts according to the manual with the TCU unplugged, the TCU needs to be replaced.

But you could very well have something going on internally as well.