Shifting issues

[tequilaiam]

On the way to work it kept dropping from 3 to 2 when I gave it any gas whatsoever, but it did go back up to 3rd when coasting. The shift from 1 to 2 feels normal, not a high rev hard shift like if the vacuum line is leaking. I have vaccuum from the pump and bypassed the valve on the IP months ago. This morning everything shifted fine and it started wanting to drop back to 2nd gear on the road.

Any ideas?

 

[mistaken1]

Doesn't the valve on the IP modulate the vacuum the transmission sees to control shift points?

 

[Dave Kay]

Crawl under your truck on the driver-side and look on the side of the transmission case. You will see a wire plugged into the side of case. Unplug the wire and test drive the truck: did it shift to 3rd now?

 

[tequilaiam]

I think vacuum valve only delays the shift on hard accelerating. If you plug the vac. pump line directly into the modulator (on the tranny) if shifts very early. Not ideal if you're drag racing between lights but makes daily driving easy.

I'll check the wiring on the transmission. What does that wire do anyway?

 

[CUCVFAN]

Kick down circuit.

 

[tequilaiam]

Is it supposed to be one wire? I pulled it, we'll see how it drives home.

 

[CUCVFAN]

Yup.

 

[tequilaiam]

Pulled it and there was no change. I checked the fluid and it looked a bit high after the drive so I sucked some out the dipstick tube and thought I saw foam come off the top. It was hard to tell in the dark with a flashlight.

So, if there was foam and if the level was high does that indicate something wrong internally? I'll give it another drive in the daylight but this has me a tad worried.

 

[tequilaiam]

Bah.....I changed the vacuum modulator, tranny filter and oil. Filter looked loose, which I read can cause foaming.

So with new stuff in there it still doesn't like to make the jump from 2-3 unless I manually work the lever from D to 2 to D again. At this point, I'm contemplating a full manual control kit.

Has anyone installed on of these? There's a sub $100 setup from Transgo, just some new gasket plates or for about $200 I can get a totally new valve body.

Can anyone recommend one or the other? I know these are made for dragsters and other high-HP monsters so I don't know how they'd function on the street. Would they increase or decrease reliability?