The parts store lists two different vacuum modulators for my 89 F150's C6. They told me that one has a green stripe and one has a purple stripe and that the only difference was that one has more aggressive shift points (shifts at a higher RPM). Anyone know which one is the more agressive or have a suggestion as to which one I should get?

 

It depends on the state of your motor. If your motor is loosing vacuum and your tranny is shifting late and hard, get the larger modulator. Id go the next larger and adjust it as needed. They have little screws you can tweak. Green stripe is the most common.

 

Is green larger than purple?

 

I installed the green one. I can not find any adjustment on it. Do you know where that screw is located that adjusts it?

 

I found the answer to this and thought I would post it incase anyone needed it. The adjustment screw is inline. You unplug the vaccuum line and the screw is inside the nozzle. The best I can tell backing the screw out makes it shift at a lower RPM and tightening it makes it shift at a higher RPM. Do not back the screw out too far. I did this and then my truck would not stay cranked. This did seem to help my transmission problems. It is still not quite right but it will shift while in drive now.

 

Cool tip! Im sorry to say I'm not real familar with workin on C6s. Never had a problem with one!

Adrianspeeder

 

I am hoping mine is alright and that some of these tweaks will get it going right. I am thinking now it might all be a problem with the vacuum lines.