AW4 Shift Woes

Hey, my old man's '90 XJ with a 4.0, auto and the like is shifting badly.

It shifts like it's floored all the time, as in it will only upshift at about 4k RPM. But it doesn't downshift like it's floored, as in it doesn't jump from 3rd to 2nd at 45+ MPH. Also, it freewheels when you accelerate and then let off the gas, but only when it ought to be in a higher gear.

We suspected that the trans was just toast, so we swapped in a known-to-be-good spare while we were rebuilding the motor. No change whatsoever in the way the trans shifts. One trans shop has already given it back scratching their heads.

I don't know much about what operates these AW4's. I assume that they are electronic shift and they do not have a "kickdown cable" to sense the throttle position. Anybody have any ideas or experience with this problem?

Thanks,
Jaredatriot:

There is a cable going to the transmission from the throttle body. I would let this be my first check since you had the motor out. Pull the little collar back and snap the throttle wide open, it will adjust itself into place. This may not be the problem, but hey, its a start.

as mentioned they do have a TV cable. I'd try a different tps, adjusted properly, and if that doesn't work swap TCU's out. The TCU is behind the knee panel under the glovebox.

After the cable check the throttle position sensor. Is the donor engine a standard shift? If so get the TPS off the old engine. They are different.

JoBo

Mine acted similar to this; new TPS fixed it.

Hey, thanks for the great replies. I'll go try resetting the cable. Thanks for the tip on the location of the trans computer. I'll let you guys know how it goes.

Jaredatriot:

JoBo said:

...engine a standard shift? If so get the TPS off the old engine. They are different...

Click to expand...

Thank you. This reply saved the day. The genius previous owner had installed a manual trans sesnor on it. It shifted like it was floored because it thought that it was floored. TPS borrowed from my '88 fixed it instantly.

Jaredatriot: