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No downshift w/ WOT

Kyle Petterson

NAXJA Forum User
Raleigh, NC
1989 4.0l AW4 - Replaced rings and rod bearings and replaced transmission pan gasket. Now transmission won't downshift w/ WOT. Shifts normal otherwise. Checked TPS, checked kickdown cable, checked grounds, check transmission fluid level - all good. Any ideas?
NEW SYMPTOM - Alright, maybe not new, but just noticed it. In P, N, and 1-2 tach works fine. In (D) and in 3, tach will stop at 2,500 - 3,000. Vehicle will keep accelerating, but tach won't move. Any ideas?
What do you mean by "shift's normal otherwise"? Does it downshift when you slow down? Does it upshift as you accelerate? Does it rev higher before shifting when you stomp on it?

Is your tach behavior consistent with the gear selection? Any starting problems?
Downshifts when slow down, upshifts with acceleration. It does not shift at a higher point if throttle is wide open. As for the tach, like I said, it works fine in P, N, and 1-2, but acts up in (D) and 3.
I wonder if you have some grounding issues. The ground strap at the back of the valve cover to the firewall is known to rot away and start causing bizzare problems like this.
Alright, here's a weird one. TPS tested good. Replaced because I ran out of ideas. New TPS tested the same as the old. Fixed problem. I tested the old one 3 or 4 times and came up with the same good readings every time and the new one tests exactly the same. So go figure.
Glad you got it. Sometimes there a "bad spot" on the TPS that doesn't show using a meter.