Overdrive Woes!

[cowboy]

I have an 89 b2 4x4 with a 91 4.0 in it. No check engine lights, runs fine. Here's the problem, originally I left the 2.9 torque converter on the a4ld so 55mph was ~3000rpms. I recently replaced with a new TC to match the motor, changed the fluid and filter and now overdrive only works when it wants to. Sometimes I can put it in OD and take off and it shifts like a top. 55mph=2000rpms. Other times I can put it in OD and it acts like its in neutral so I throw it in drive and it runs fine just no OD. It's not losing fluid. Fluid isn't burnt. Good cooler. New speed sensor and throttle position sensor. Any ideas guys? I'm at a loss. I have an FM146 that I know is good I could do the swap with but I've got a REAL bad left knee from being in the military so I'd really rather stay automatic you know?

Thanks people.

 

[Flint311]

First of all, thank you for your service to the country!

I gotta check some stuff out on my daughters '93 A4LD. Everything I've read, it could be the key cylinder (worn and not making contact for solenoid in tranny), faulty solenoid or power to it, modulator, or leaking/faulty solenoid. Others may have more/better ideas. There's several "serviceable" parts you can do at home.....