Where does the A4LD modulator vacuum line connect on manifold

[Devo55]

I have a 93 Explorer Sport 4.0 with a whopping 365,000 miles. Recently the it just stopped 1-2 shifting. I was driving along then I felt a whoosh, like a balloon releasing it's air. My truck went straight to first gear. Luckily, I was on a back street with no traffic because I could only do 20mph after that. Now when I drive I have to let the rpms go to 2000 then ease of the gas until it drops to 1500rpms and it will shift into second. I changed the modulator (with a Duralast MVP14 from Autozone) and it didn't fix the problem, infact, it got worse. It still wouldn't shift automatically, l had to let off the gas to get it to shift gears but now the tachometer had to climb to 3000rpms and only then it would sometimes shift into second gear. Sometimes it would jump back to first gear without warning. I suspect the modulator may have been bad in the box or just the wrong one. I pulled the Duralast out and put the old one back in, because no nearby auto parts had one in stock and need to drive to work. I ordered a new modulator online and should be here in a few days.
Side note: I tested my old modulator with a vacuum and it held 20 -17 inches of vacuum for almost 7 minutes. Pretty good! The hose did have a bit of ATF when I pulled it off the transmission though. The Duralast held 20 inches of vacuum for a few mins too but it's definitely not right for my truck.

So my question is, does anyone know where does the vacuum line from the modulator connect on the intake manifold? I want to make sure the line the vacuum line has no leaks, but I can't find where it connects exactly. I tried to follow it from underneath the truck but got lost in the maze of wiring. It's also very sketchy on diagrams. I need a picture. "This is the A4LD vacuum hose --- it connect here". Any Ford scholars there?

 

[Josh P]

The vacuum tree is on the back of the intake manifold on the drivers side. There is a pin that goes in the modulator, did it end up in the new one?

 

[Devo55]

The vacuum tree is on the back of the intake manifold on the drivers side. There is a pin that goes in the modulator, did it end up in the new one?

Yeah I did take the pin out of the old modulator and placed it in the new one. Still didn't shift. So the transmission line def connects to the vacuum tree? I'll check it again.

 

[410Fortune]

Yes the vacuum tree back of intake drivers side near wiper
Motor
The a4ld has a hard line and the soft rubber line that goes up the spine of the transmission up around the back of the intake and to one of the larger feeds off that tree

 

[Devo55]

Yes the vacuum tree back of intake drivers side near wiper
Motor
The a4ld has a hard line and the soft rubber line that goes up the spine of the transmission up around the back of the intake and to one of the larger feeds off that tree

Thanks! I found it. Did a vacuum test on the line to the modulator. It held at 20 inches. Started the truck and did a vacuum test at the manifold port where the vacuum hose connects. Same result, 20 inches.

My old modulator had some ATF in the small hose when I took it off but it still holds a 20 -18 inch vacuum for almost 5 minutes. How is this possible?

 

[Technoguyfication]

Thanks! I found it. Did a vacuum test on the line to the modulator. It held at 20 inches. Started the truck and did a vacuum test at the manifold port where the vacuum hose connects. Same result, 20 inches.

My old modulator had some ATF in the small hose when I took it off but it still holds a 20 -18 inch vacuum for almost 5 minutes. How is this possible?

Hey Devo,

Did you ever figure this out? I'm having the same symptoms you described in the original post with the trans in my 94 Explorer. I just did a rebuild and swapped in a non-adjustable modulator from the rebuild kit. I suspect it may be bad, or it's not adjusted correctly for the transmission. Just wondering what you did to solve the issue.

 

[Josh P]

Hey Devo,

Did you ever figure this out? I'm having the same symptoms you described in the original post with the trans in my 94 Explorer. I just did a rebuild and swapped in a non-adjustable modulator from the rebuild kit. I suspect it may be bad, or it's not adjusted correctly for the transmission. Just wondering what you did to solve the issue.

Does the transmission shift if you start out with the shifter in 1st then manually shift it to 2nd when rolling?

 

[Technoguyfication]

Does the transmission shift if you start out with the shifter in 1st then manually shift it to 2nd when rolling?

Yes, I wanted to update this thread with my fix to the problem. I used a rebuild kit that came with a new, non-adjustable vacuum modulator. Something about this modulator isn’t calibrated right for the transmission and it was causing it to not want to shift at all. I could get it from 1-2 if I revved super high, but that’s it. I dug the old modulator out of the trash and put it in, everything works perfectly now.