Trans. Shifting Problem

[BlackEXP-93]

I've started having this problem with my truck, a 93 Explorer 4WD Automatic.

The problem seems to be that it isn't shifting into 4th gear. (Somewhere around 55mph it should shift) I'm pretty sure 55mph is 4th gear anyhow.

I noticed this because I drive a 55mph highway nearly everyday, and have gotten used to feeling when the vehicle shifts. It isn't shifting into the final gear, which in turn means I have to press the accelerator more, and the engine's RPMs are around 3,000.

The cruise control also doesn't seem to want to work either. whether or not this has anything to do with the shifting problem I have no idea.

Does anyone have any possible reasons? Is my Tran dying?

 

[ricco750]

My hunch is that it is a vacuum related problem. Both your vacuum modulator valve (responsible for proper shifting) and your cruise control are driven by engine vacuum. I would start at the big vacuum tee at the right rear of the engine, and trace all the lines. Also, see if there is transmission fluid in your vacuum modulator hose. That's a sure sign the modulator is bad.

 

[BlackEXP-93]

Also, see if there is transmission fluid in your vacuum modulator hose. That's a sure sign the modulator is bad.

The more I read up on it the more I think it is the problem with the modulator valve itself. Unfortunately I wasn't able to check the lines, or the valve, because I could barely see the line going to the valve, or even where it is supposed to be located (passenger side of the transmission).

It looked like the catalytic converter was in the way, but perhaps not. I think I read somewhere about removing the transmission drip pan, but I'm not sure. I did notice that the underside of the pan has some fluid on it, however none was dripping.

Could anyone provide any SPECIFIC details for locating, checking, and removing the Vacuum Modulator Valve?

 

[BrooklynBay]

The modulator is to the rear of the 2 servos. It might be covered by a heat shield so it's hard to get to. There is an access panel in the hump on the floor. Did you ever adjust your kickdown cable?

 

[BrooklynBay]

 

[ricco750]

The more I read up on it the more I think it is the problem with the modulator valve itself. Unfortunately I wasn't able to check the lines, or the valve, because I could barely see the line going to the valve, or even where it is supposed to be located (passenger side of the transmission).

It looked like the catalytic converter was in the way, but perhaps not. I think I read somewhere about removing the transmission drip pan, but I'm not sure. I did notice that the underside of the pan has some fluid on it, however none was dripping.

Could anyone provide any SPECIFIC details for locating, checking, and removing the Vacuum Modulator Valve?

I'm gonna replace my vacmod today, going in from the top (remove front seats and center console). I'll let you know how it goes. I've been procrastinating this job for about 6 weeks.

 

[ricco750]

Vacuum Modulator Replacement Completed!

OK, I'm finished. This is not a complicated job, just a PITA. It took me about 6 hours...I think I read in a post by DeRocha that he did it in two and half hours...maybe he had practice.

Anyway, the seats come out first...each has four 13mm bolts that hold it to the floorpan, and a torx bolt that holds the seat belt fastener anchor. Then the console comes off. Remove the plastic trim that covers the panels as the floor transitions up toward the dash, and loosen the trim panel that holds the carpet to the floor. Pull back the carpet from the front to expose a large inspection panel over the tranny...remove four bolts and lift the panel off. You will now see the vacmod behind a heat shield. Remove the nut that holds the heat shield, and slide the heat shield forward to move it out of the way. Then remove the stud that holds the clamp on the vacmod, which will now easily pull out. Be careful not to lose the pin that is in the vacmod. This was not included with my replacement part, I guess it's considered part of the tranny. It's a little over an inch long, about 1/16" in diameter.

WARNING: When you pull out the vacmod, fluid will slowly drain out of the hole. I did not know this, and after about 45 minutes it must have drained about 5 or 6 ounces of fluid on my shop floor. I should have put a pan underneath to prevent the mess. You will probably want to put a new piece of rubber vacuum line on that goes from the vacmod to the metal line. Mine was about 4 inches long. Hope this helps.

 

[BlackEXP-93]

Well, after several hours of work, replacing the Vacuum Modulator didn't work to solve the problem. I couldn't remove the drive seat due to a rusted through bolt, and couldn't figure out how to remove the center console, so after removing the pass. seat I just peeled the carpet back and opened the panel like that.

There was a little fluid in the hose, so the modulator was bad. After swapping it out with the new one, and putting everything back together, I took it for a test drive.

Starting out, it had trouble going into 2nd gear (about 25mph). When it would try and shift, the RPMs would go to about 2000 and then it shifted. I had this problem accelerating several times before going onto the highway. When accelerating on the onramp, it wasn't shifting out of 2nd gear. I pushed the accelerator down more, the RPMs at 4000, yet the vehicle only going 35-40mph. After I slowed down and began again, it got up to speed. On the highway it still wouldn't shift into 4th gear, and the cruise control still doesn't work. I went up and down a small strech just to be sure.

After getting off the highway, it didn't have the 2nd gear problem and was shifting like normal.

I did loose a bit of tran fluid, but that doesn't seem to explain why the same 4th gear problem is occuring with a new Vac Mod.

Before I take it to a mechanic is there anything else I can check myself?

 

[BrooklynBay]

The servos might be bad or the bands might need to be adjusted.

 

[daydreamer]

We had a similar problem with the wife's 94 XLT Explorer. It would not shift into the last gear at 55. Also sometimes had problems with the cruise control working. I pulled the vacuum hose off the fuel pressure regulator and saw it was wet in there (with gasoline). Just don't pull the vacuum hose off your fuel pressure regulator on a hot engine (don't want to start a fire). After changing the fuel pressure regulator it now shifts at 55. I guess the gasoline in the vacuum hoses messed it up somehow. Not sure if the cruise is better as we haven't tried it lately.

 

[Jack Flash]

not shifting to 4th/OD had nothing to do with the modulator. OD is electronically shifted via a shift solenoid inside the pan. Glacier's A4LD rebuild and lots of other posts in this forum tell the same thing. since the modulator was leaking, it was good that you replaced it anyway.

if your OD and cruise control quit at the same time, I would suggest checking all the connectors on the tranny. this points to the VSS possibly malfunctioning. could be a bad VSS; haven't run across one yet but they do go bad.

also, check the 3-4 (OD) shift solenoid with an ohmmeter and by applying 12v from an outside source. I have seen a couple of solenoids that checked ok with an ohmmeter, but failed the 12v test due to being clogged or stuck. the valve body will have to be pulled out to replace the solevoid.

since there was no major debris in the pan (<----I'm guessing), your OD unit may be ok. you also need to check the adjustment of the OD band. to determine which OD band you have, read Glacier's A4LD rebuild. you will have to drop the pan to see which band is there to make the correct adjustment.

hope these suggestions will get you on the right track to curing your problem.
.
.
.

 

[MustangDos]

I had the same problem w/ mine. I fixed it this am by pluggin in one of the loose electrical connectors on the side of the tranny near the shift lever....all is working now..

 

[BlackEXP-93]

since there was no major debris in the pan (<----I'm guessing), your OD unit may be ok. you also need to check the adjustment of the OD band. to determine which OD band you have, read Glacier's A4LD rebuild. you will have to drop the pan to see which band is there to make the correct adjustment.

hope these suggestions will get you on the right track to curing your problem.

I actually didn't drop the pan to replace the VacMod, I went in through the inside access panel over the tranny, in front of the center console. I oroginally went to drop the pan, but when I removed most of the bolts around the outside, and transmission fluid began to drip out, I thought I was doing it wrong and put the bolts back in, and went in from the top.

I'll check the below two problems first. I'm hopeful they may help...

It would not shift into the last gear at 55. Also sometimes had problems with the cruise control working. I pulled the vacuum hose off the fuel pressure regulator and saw it was wet in there (with gasoline). Just don't pull the vacuum hose off your fuel pressure regulator on a hot engine (don't want to start a fire). After changing the fuel pressure regulator it now shifts at 55. I guess the gasoline in the vacuum hoses messed it up somehow

I had the same problem w/ mine. I fixed it this am by pluggin in one of the loose electrical connectors on the side of the tranny near the shift lever....all is working now.

I'll try looking at these on my next day off. Hopefully I won't have to so into the transmission. =P

 

[BlackEXP-93]

Eh, I forgot to include a potentially important symptom.

When I'm driving, at say 45mph, the tachometer is around 2500rpm. However, when I let off the gas completely, the gauge quickly goes down to about 1000rpm, or even 500rpm (Idle speed I believe). I don't know why I'm just now mentioning this, but it seems to be a possible symptom for the problem I'm having.

Could this be caused by poor engine vacuume? Or would it be low fuel pressure due to something else? And how would this effect my transmission problem?

I've had a problem in the past where coolant got into one of my cylinders through a cracked head, but when that happened the pressure was worse and the engine would not idle high enough to stay running. I got a mechanic to fix the leak and put a sealant on the cylinder head. I know it wasn't a permanent fix and my truck is doomed in the long run, but RIGHT NOW I'm pretty sure it isn't the problem because of the transmission problem.

 

[letmein2]

BlacExp-93,
Did you get your fix?
Would like to know since I have similar problem with my 94' Explorer Sport.
It won't auto shift pass 2nd gear. I have to push the accelerator to get 4000RPM then slow it down and push the accelerator again before it can engaged.

 

[BlackEXP-93]

Nope. And I doubt I will. I have a grave feeling that it is my transmission that is messed up, that one of the bands may have broke or whatever happens inside a tranny. I've been driving my truck in 3rd gear for 6 months now. It isn't usually a problem under 50mph because the 4th gear kicks in at around 50-55mph for highway speeds. The road I take to work is a 55mph road, and it's 10 miles I travel to get there. I know it's bad to drive a truck like that, but it's all I can do because I can't afford a tranny rebuild. When I put the Shift gear in D instead of OD, I don't have the tachometer RPM issue mentioned in the last post.

Sorry I couldn't be of much help letmein2...

 

[35Remmy]

My OD went out on my '88Ranger, A4LD and the transmission lasted just a few months more. Burned her up, although she had close to 275,000 miles on the original transmission. GREAT truck. Had a high-performance rebuild done to that A4LD, but engine blew like 4,000 miles later. Still have her...waiting to put in the 351W, heh. $$ has been REAL tight these days for projects like this one.

 

[1sikstang]

not shifting to 4th/OD had nothing to do with the modulator. OD is electronically shifted via a shift solenoid inside the pan...
if your OD and cruise control quit at the same time, I would suggest checking all the connectors on the tranny. this points to the VSS possibly malfunctioning. could be a bad VSS; haven't run across one yet but they do go bad.
.
.
.

This is correct... I had the same exact symptoms BlackEXP, and it turned out that the speed sensor connector had came unplugged. Cleaned the connector, plugged back in, and now I have working CC, T/C lock-up, and O/D. I can't stress enough that the electrical connectors on the trans. should be inspected, as it's very easy and costs nothing at all!