AT holds 1st gear

[Sstrretch]

trying to help fix my buddies truck... he's got a 91 ford ranger extended cab 2wd 3.0 6cyl... holds first gear to about 4k rpm and when shifting into reverse, it doesn't idle down and jump into gear.. did some searching and came up with a vacuum module... he had someone rebuild his motor and now instead of having the double hump intake, it now has a single side... now i can't seem to find out where that hose from the vacuum module goes to... wasn't sure if it ran to a canister/plunger first then the vacuum hub or straight to the hub? tube has "t" that has been plugged.. seems like the vacuum tube that comes up the firewall goes towards the front the the motor on the side instead of going straight to hub....? don't know if the other guy by-passed it or whatever... any ideas? much appreciated!!! thanks in advance....~Ron

 

[Earl43P]

Most Fords have a vaccum diagram either on the underside of the hood or the top of the radiator support.

I can look at this 93 vaccum diagram and tell you that the tranny gets a straight line from the vaccum distribution block. So does the Cruise, brake booster. Another hose goes to a checkvalve (single line in, dual out) one line going to the HVAC reservoir, the other to inside the cab for heater controls.

So, no T in the tranny vaccum line.

 

[Sstrretch]

checked under hood and no diagram for the tranny vac line... so then the line coming from the vac mod goes into a hose line straight to the vacuum distribution block? right? so problem prolly consists of getting the vac mod...? will that solve the hard shifting prob going into reverse also? thanks again

 

[Runnin'OnEmpty]

checked under hood and no diagram for the tranny vac line... so then the line coming from the vac mod goes into a hose line straight to the vacuum distribution block? right? so problem prolly consists of getting the vac mod...? will that solve the hard shifting prob going into reverse also? thanks again

It should. The vacuum modulator does what the name says;
it 'modulates' the shifts by changing the line pressure according
to manifold vacuum.

Another thing that might cause a hanging shift is the governer
located inside the tailshaft. Sometimes they'll bind up at high
mileage, and cause shifting problems.

I'd go with the vac mod first, though.

 

[Sstrretch]

thanks... will start with the vac.... hopefully that solves it...

 

[Sstrretch]

buddy was wondering if the govenor would control all gear shifting cuz problem is it hard shifts into reverse and holds 1st gear to 3500 rpms but is smooth after that....? thank

 

[Runnin'OnEmpty]

buddy was wondering if the govenor would control all gear shifting cuz problem is it hard shifts into reverse and holds 1st gear to 3500 rpms but is smooth after that....? thank

I assume this is an A4LD in the 91?
The govenor reads the vehicle speed and helps to determine the
speed at which the trans shifts. It might be the cause of 1st
gear hanging too long, but shouldn't have any effect on the
hard reverse shift.

It almost sounds like the line pressure is too high, giving the
hard reverse shift. The vacuum modulator varies the pressure,
so I'd look at that. There's a small actuator rod that's in the
vac mod bore behind the unit, so make sure it's not missing
or out of position.

If you have to go into it further,
the low/reverse servo is accessed by removing the pan, and
it does tend to get lots of buildup from gunk and debris....

 

[Sstrretch]

was wondering if u could point in the direction of complete lay-outs/prints...? will let u know how this turns out... thanks again!!! !Ron

 

[Sstrretch]

having to pull vac. mod., for color code for replacement part, but, unable to remove it..... any suggestions? it has just 1 bolt holding retainer support...??? does it come straight out, or is it threaded?? Or would u know color code for this truck? thanks again, Ron

 

[Runnin'OnEmpty]

having to pull vac. mod., for color code for replacement part, but, unable to remove it..... any suggestions? it has just 1 bolt holding retainer support...??? does it come straight out, or is it threaded?? Or would u know color code for this truck? thanks again, Ron

Try this link for more info on vacuum modulators:
http://www.rockauto.com/catalog/x,carcode,1137765,parttype,8500

I suspect you're looking for a brown striped modulator, but don't
quote me on that. There's also a high-altitude unit available.

Yes, there's only one bolt for the retainer, and then the modulator
simply pulls out. It has an O-ring seal, and a small pin actuator that's
behind the modulator. DON'T LOSE THE PIN!!! It's small and
easy to lose, and very hard to replace........

If it's hard to pull out, try prying with a small screwdriver, or a knife
blade. It's not threaded, just pushed in, but access is probably limited
in some cases......

Good luck, hope that fixes it.

 

[DCinDC]

Sounds like the hose is off....

It goes to a manifold vacuum source. They come off alot, if the pipe isn't clipped to the bellhousing.