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AW4 acting like a 5 speed???

L

larry91xj

NAXJA Forum User
Location
colorado
I have a 91 xj 4.0, and the transmission is acting really funny. While getting up to highway speed my transmission will shift through all 4 gears and then the rpm's will drop another 6-700 rpm, just like there was another gear after overdrive. If I push on the accelerator the trans will downshift into 3rd like it should but as soon as i get off of the pedal it will do the same thing. I unplugged the tcu and did not experence this problem. Tested tps and all is good, any ideas, before I have to take this thing to the tranny shop??
 
the AW4 is effectively a 6 speed, though more common to experience 5 speeds. the reason for this is the lockup torque convertor which will lock under certain conditions in 3rd and 4th gear. so you have 1, 2, 3, 3 & tc, 4, 4 & tc. it is not as common to have the torque convertor lock in 3rd as in 4th.

also, when the torque convertor locks, the tranny is more efficient, which means better gas mileage and less heat in the tranny, this is a good thing, do not be concerned.

i swapped an AW4 without using the TCU and used a 5 position rotary switch for gears 1 through 4 and the 5th position being 4th gear with the convertor locked, like you are experiencing. then i also have a toggle that i can lock the torque convertor in any gear.
 
are you just sending a straight 12v to the tranny solenoids? I was kicking around the idea of making a switch/push button style shift set-up, but wasnt' sure what the voltage was to the solenoids.

Josh
 
JBrobeck said:
are you just sending a straight 12v to the tranny solenoids? I was kicking around the idea of making a switch/push button style shift set-up, but wasnt' sure what the voltage was to the solenoids.

Josh
Click to expand...

Not sure how far this ever got, but on the XJ list @ Moab OffRoad I think someone built a unit like that within the last year. You might want to ask about that there.
 
I have it all written up in diagrams how to do a complete electronic shift with 2 momentary contact switches, though you have to lock the converter yourself via another manual switch. It would essentially be the same as the steeringwheel mounted shifters in some of the newer cars, but I haven't had the time to research the actual voltage output to the solenoids and I don't wanna burn anything out! If I find that I don't need to do any further developement, I will do a writeup and diagram of my setup after I give it a trial run for a little while.

Josh
 
Josh, There was someone on this board a couple of months ago that was designing a push button tranny control using diodes. The basic idea was an on/off switch to activate the unit and then four push buttons to select the desired gear and another button to lock/unlock the torque converter. My understanding was that all of the design and diagrams were done and it was awaiting an install. If all went well there was supposed to be a write up with pictures. Sorry I can’t remember the guy’s name, but he was enrolled in some type of college electronics class and this was going to be a project. If you decide to do this your self or run across anyone else who has please post the results. I’d love to have a set up like that. BTW I have a write up on how to a manual conversion and torque converter lock/unlock, but it is not nearly as nice as a push button setup. PM me with your email address and I’ll send you a copy of the file. I would give you the web address for it, but I cut and pasted the article into word and I don’t remember where I originally found it.

Terry
 
mad maXJ said:
the AW4 is effectively a 6 speed, though more common to experience 5 speeds. the reason for this is the lockup torque convertor which will lock under certain conditions in 3rd and 4th gear. so you have 1, 2, 3, 3 & tc, 4, 4 & tc. it is not as common to have the torque convertor lock in 3rd as in 4th.

also, when the torque convertor locks, the tranny is more efficient, which means better gas mileage and less heat in the tranny, this is a good thing, do not be concerned.

i swapped an AW4 without using the TCU and used a 5 position rotary switch for gears 1 through 4 and the 5th position being 4th gear with the convertor locked, like you are experiencing. then i also have a toggle that i can lock the torque convertor in any gear.
Click to expand...

My 87 lacked a tachometer, so it's a little hard to be sure, but my impression was that it went 1-2-3-3TC-4TC, in other words, if accelerated smoothly, it seemed to shift from 3 to 4 without unlocking. If accelerated hard, for instance going onto a freeway ramp with a trailer, it would wait until after it was in fourth to lock the TC.
 
I remember reading that somewhere also, thats where I got the Idea from, mine is a slight variation, but with 2 switches, an upswitch and downswitch with a manual T.C. lockup switch seperate from the other 2. This way you cannot accidentally skip gears (although some may want to). When that original post was made I started drawing something up but lost interest cause it started to get really confusing. He mentioned that he was doing something electrical in college, and it got me thinking of my friend who goes to Dunwoody college here in the twin cities (big electical/tech college) He has a program on his school laptop that allows you to build circuits in the program and test them. Its quite a few relays but really pretty simple, we have a problem with it defaulting to O.D. when we turned it on, so something is kind of backwards but that will get figured out. Its been a couple weeks since we have putzed with it cause I didn't know if I would be able to just send 12v straight to the solenoids, but its looking like that is the way it will work. I'll try and keep everyone updated, it'll be a little bit yet, but should be cool if it works.

Josh
 
If you have the shifter in "D", then the shift pattern will be 1-2-3-4-4locked.
If you have the shifter in 3rd, then the shift pattern will be 1-2-3-3locked.
If you have the shifter in 1-2, the pattern is 1-2-2locked.

Unfortunately, when in D and a downshift from 4locked is needed, it goes straight down to 3rd gear, unlocked. I find this rather annoying on the highway, when all I really need is a few hundred rpm that the unlocked converter would give me in 4th...

The transmission only has 4 forward ratios, but the torque converter locking in 2nd, 3rd and 4th makes it feel like there are 3 additional "gears". However, the tranny will only lock up the highest gear you have the shifter selected for.

I drive around in 3rd most of the time, so there are 3 "shifts" (1-2-3-3lock), then if I click it into "D" there are 2 more shifts (4 and 4lock), so it feels a bit like a 5 speed auto. The higher you rev it, the less rpm difference there will be between unlocked and locked, because the converter is slipping less. If you time everything right though, it sounds just like a 5 speed! :>)

Cheap entertainment.....
 
Last edited:
AndyS said:
If you have the shifter in "D", then the shift pattern will be 1-2-3-4-4locked.
If you have the shifter in 3rd, then the shift pattern will be 1-2-3-3locked.
If you have the shifter in 1-2, the pattern is 1-2-2locked.

Unfortunately, when in D and a downshift from 4locked is needed, it goes straight down to 3rd gear, unlocked. I find this rather annoying on the highway, when all I really need is a few hundred rpm that the unlocked converter would give me in 4th...

The transmission only has 4 forward ratios, but the torque converter locking in 2nd, 3rd and 4th makes it feel like there are 3 additional "gears". However, the tranny will only lock up the highest gear you have the shifter selected for.

I drive around in 3rd most of the time, so there are 3 "shifts" (1-2-3-3lock), then if I click it into "D" there are 2 more shifts (4 and 4lock), so it feels a bit like a 5 speed auto. The higher you rev it, the less rpm difference there will be between unlocked and locked, because the converter is slipping less. If you time everything right though, it sounds just like a 5 speed! :>)

Cheap entertainment.....
Click to expand...

Actually, according to the Factory Service Manual (and my memory, no manual at hand here), in "D" it will lock in both third and fourth, and in "3" it will lock in second and third.
 
has anyone worked this all out for the newer tranys?? i know there was alot of discussion last year about this subject... doesnt it have to do with the OBD system controling the trans now in the newer XJs.. (sorry about the hijack)

mike
 
JBrobeck said:
I remember reading that somewhere also, thats where I got the Idea from, mine is a slight variation, but with 2 switches, an upswitch and downswitch with a manual T.C. lockup switch seperate from the other 2. This way you cannot accidentally skip gears (although some may want to). When that original post was made I started drawing something up but lost interest cause it started to get really confusing. He mentioned that he was doing something electrical in college, and it got me thinking of my friend who goes to Dunwoody college here in the twin cities (big electical/tech college) He has a program on his school laptop that allows you to build circuits in the program and test them. Its quite a few relays but really pretty simple, we have a problem with it defaulting to O.D. when we turned it on, so something is kind of backwards but that will get figured out. Its been a couple weeks since we have putzed with it cause I didn't know if I would be able to just send 12v straight to the solenoids, but its looking like that is the way it will work. I'll try and keep everyone updated, it'll be a little bit yet, but should be cool if it works.
Click to expand...

...any update?!??! i know its been like a year....gotta have made some sort of headway....or just given up?
 
KinesthesiaDrums said:
...any update?!??! i know its been like a year....gotta have made some sort of headway....or just given up?
Click to expand...
it looks like he hasn't logged on in 3 months, so I don't think you can expect a reply from him. I have something similar now, and when I'm not working 60 hours a week (after the holidays) I plan on getting something together like he describes with momentary pushbuttons for up and down shift as well as an on/off pushbutton for torque convertor lock, and indicator LEDs for all of it to show you what gear you're in.
 
Brett,
I'm more than capable of engineering the pushbuttons, can you send me some schematics of your shifting kit? I'll be happy to do the engineering work and send it back to you. My brother has an AW4 and he want steering wheel paddles. I've even devised a homemade paddle system on the GM column.
 
Did you all see that there is a company who is making a steering wheel paddle shifter for the GM columns. It was in the latest Petersen's.

Brett, LED might help a little, but I think if the gears are clearly marked on yours, then it shouldn't be an issue.

I plan on ordering from you soon.


Erik
 
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