Hello All, Ive been trying to figure out my transmission problem for about a week now. My car is an 88T with the E4n71B. And after reading the trouble shoot in the fsm, my probelm is most likely a Vacuum diaphragm issue. Its located on the driver side of the tranny right next to the downshift solenoid.
My Question is.... is there supost to be a vacuum hose connected to this??? The FSM shows a hose coming off it, but i wasnt sure if it was a vent to atmosphere type or it acually needs to be hooked up to the engine vacuum supply.

My trans has the following problems
Rough shift 1-2
No OD even after a long warm up
shifts are always different with about the same throttle given

 

Yes, there should be a vacuum line connected to the modulator. There should be a small plunger pin that the modulator pushes against to work the valve inside the tranny, but ATF will pour out the hole if you unscrew the modulator without draining the sump.

 

awesome ken! but where on gods green earth does the vacuum line go?

 

OK so i think i know what my car is missing.... the metal tube the connects the vacuum diaphragm to the intake manifold. Great! time to find one of those now. And answer the other post some guy wrote "whats this metal tube coming from my tranny" in the other fourm.

 

Car is fixed!!! Added the steel tube between the vac diaphragm and intake that the PO decided to leave off and confuse the crap out of me. All problems listed above are gone! If any of yall have weird tranny problems.... Check the vac at this valve first it's a HUGE PART on how the tranny works!

 

 

What if the car only runs on 1st and 2nd gear? Automatic transmission..