1994 Mazda b4000 a4ld problems

[callmedak]

I’ve got a 1994 Mazda b4000 with the a4ld haven’t owned it very long and when I got it I noticed it the trans was lagging and not shifting properly. When when in drive or overdrive it won’t shift out of first until around 4k rpm and then I’m not sure if it’s shifting or slipping in the 2nd/3rd shift it’ll go until 4k/4.5k and then jolt hard but only to drop rpm and then go back up high rpm as you accelerate. Sometimes once you get around 50-55 mph it’ll shift into overdrive and it’ll act normal low rpm and won’t go above 3k and drive fine. Even if you manually put it in first and shift up it won’t shift until you put it back in drive and ride it out til 4k. After draining trans fluid it’s definitely burnt more than it should be but not seeing any flakes or metal. Haven’t dropped the pan yet figured I’d look around and get opinions if it’s worth looking into or is it not worth it and just go ahead with a rebuild

 

[RonD]

Reads like a transmission vacuum modulator issue

On the passenger side of the transmission is the Vacuum Modulator, has a vacuum hose up to the intake manifold, make sure hose is hooked up and air tight no cracks/leaks
Check for ATF fluid in the hose or leaking out of the modulator

Also put another hose on modulator and suck on it to see if modulator can hold a Vacuum

Vacuum modulator conveys engine LOAD level to transmission, so is part of shift point strategy

 

[Josh B]

Hey Dak, good luck with it, welcome to TRS

 

[callmedak]

Reads like a transmission vacuum modulator issue

On the passenger side of the transmission is the Vacuum Modulator, has a vacuum hose up to the intake manifold, make sure hose is hooked up and air tight no cracks/leaks
Check for ATF fluid in the hose or leaking out of the modulator

Also put another hose on modulator and suck on it to see if modulator can hold a Vacuum

Vacuum modulator conveys engine LOAD level to transmission, so is part of shift point strategy

You were correct I got around to it today took the interior out and went through the panel on trans tunnel to find the line to the modulator not even connected. I’ve got receipts from the previous owner for trans work at a shop guess they didn’t hook it back up is my best guess.