torque convereter not locking up

[thedirtyneck]

I have searched around for info about this and i have found some but i need more ideas.....

My torque converter is not locking up and wanted to know what people would try to fix it. I changed my transmission filter and flushed the fluid but that did not work.... What should i try now???

O2 sensors???
Voltage regulator???
Vacuum Pressure Sensor??? (I think that's right)

any suggestions will be helpful...

Also does anyone know how to tell if your torgue convertor has failed mechanically? I know of a stall test but i cant find the specs anywhere.

Thanks

 

[MrShorty]

Here's what I did as I've done some troubleshooting on my torque converter clutch. First the basic test for tcc engagement out of the manuals. With engine at operating temperature and while maintaining a constant speed above 50 mph, tap on the brake and you should see a jump in the engine rpm as the tcc disengages.

Second is to be absolutely certain the computer is telling the tcc to engage or disengage. I may catch some flack for this, but I used a volt meter hooked up to the tcc engagement circuit and monitored it while driving. I forget which state is on or off, but essentially there is a choice of 12 volts or 0 volts, and you'll easily see when the computer tells the tcc to engage. If the computer doesn't tell the tcc to engage, and the tcc circuitry is intact, then there is a problem in one of the sensors so that the computer doesn't want to engage the tcc. (This is when I wish I had a good scanner that would monitor the sensors while I was driving.)
If, as in my case, the computer tells the tcc to engage, but the tcc doesn't engage, then there is an internal transmission fault. Dirty valve body, bad torque converter, etc. That's where I'm at on mine, the computer tells the tcc to lock, but it doesn't effectively lock up.

 

[410Fortune]

Thats right! there are two wires that go from the EEC-IV computer box to the A4LD transmission. One is the 3-4 shift (overdrive) and the other is the convertor lock up.

You can locate the TC wire in the tranny harness, hook up a volt meter or a test light and drive the truck, you will be able to tell when the EEC tells the convertor to lock up/unlock. This is the first place to start.......

I dont have the info here with me but I can tell you exactly what wire to look at if you need me too....

 

[thedirtyneck]

Thank you both for the info... I had no idea you could test the the torque converter that way. But it will be my next step. Where is the best place to hook up to the wire?

410Fortune... if you can send me more info about what wire i need to monitor that would be great.

Thanks again for the info

 

[410Fortune]

The easiest place to locate the wires going down to the transmission is on the drivers side, near the upper intake manifold (right around the dipstick). You will see a harness goes through the upper intake and down the back of the 4.0L to the tranny. There is a round plug with 8 wires in it, 5 of which continue on to the 5 wire key shaped plug that go into the tranny. The other 3 wires are the oil level sensor, oil pressure sensor, and the canister purge sensor wire. I'll give you more details when I have the wiring schematics in front of me.

The wires that go to the A4LD are:
reverse light sensor purple/black
neautral sensor lblue/yellow
3-4 shift signal
torque convertor lock up signal
electric shift neautral sensor red/w

Those colors are from memory. I believe the 3-4 shift wire is purple/yellow and the torque convertor lock up is orange/yellow, however without the book this is useless.............

You can also get the TC wire and the 3-4 shift wires right at the 60 pin plug that goes into the EEC (under pass side kick panel)

 

[thedirtyneck]

I was driving around last night and when I tap on the brake the rpms drop slightly, they do not go up as they should. This confirms that the torque converter is ont locking and unlocking. Wells thats as far as i have gotten so far but i will update after i tap into the wire(if i can find it) and test it that way.

 

[MyExpWork]

What are the symptons of the torque converter not locking up?

If it does not lock up, what problems would it cause? I know nothing about how these things work.

Someone educate me.

What would your truck do, to lead you to beleive that your tc is not locking?

Brian

 

[thedirtyneck]

I first noticed something wasnt quite right because my rpms are really high when driving. On the interstate crusing at 70 mph on pretty flat ground I am turning somewhere around 3400 rpms. This is what clued me in to the fact that something was wrong.

I was told to get up to speed at about 55mph then apply some gas. Your rpms should increase at the same rate as your speed, instead of rpms jumping up and then the speed catching up like when you start out in first gear. Your torque converter is not locked up in first or second gear and this is why your rpms jump up when you hit the gas. Im not sure but i think the torque converter partially kicks in (about 60%) in 3rd gear and then fully locks up in 4th gear.

I dont know if that helps at all but thats about all I know. Check out www.howstuffworks.com they explain car stuff pretty well most of the time.

 

[410Fortune]

You've got it backwards.

If the convertor isnt locking up you can tell like this:

Get up to speed, 55 or 65 MPH, whatever. Let off the gas, if the RPM's drop down to 1500 and you are still doing 60 MPH then it's not locked up. Basically if the convertor doesnt lock up the engine will try to return to an idle while the truck still rolls along at speed...

Make sense? It's like if your doing 65 in a stick and you hold the clutch in (disengadge) the engine RPM's will slow down, until you let the clutch back out....

If the convertor is not locking up with the computer controlled solenoid then it's just like depressing the clutch........

The torque convertor in the A4LD is hydraulic to a point, the A4LD is a 3 speed transmission, but if you notice in OD it has 5 shifts. The 4th shift is the computer forcing the convertor to lock up. Until then it works just like any other hydraulic torque convertor.....the 5th shift is the computer controlled 3-4 Overdirve shift.....

the A4LD is actually a very cool transmission, it just gets a bad wrap because the aluminum overdrive parts can wear out early when not taken care of properly......

I have seen 160K hard miles from an A4LD when maintained properly (fluid and filter every year, proper fluid level, proper speedo gear for tires/gear ratio, and a good tranny cooler). Then I have also seen them fail after 10K miles because of a crappy rebuild.
Yes it could be better, and there are much stronger tranny's out there, but Explorer's didnt come with those so unless you like custom adapters and setups, your stuck with an A4LD. If anybody wants a heavy duty rebuild for their A4LD let me know, I know a guy here in CO who can do it. He rebuilt mine and I can tell you it is a monster.......it's not cheap, but he stands behind his work and he DEFINATLEY knows what he is doing.....

 

[thedirtyneck]

ok that makes sense but shouldnt the same hold true if you push on the gas instead of letting off of it? If the rpms do not increase or decrease at the same rate as the speed then the converter is not locked up, is that correct?

410Fortune, you said i can tap in to the wires near the computer in the passenger kick panel? did you do it this way or what? i just figured that would be easier to do since it is inside the truck. How would you recomend going about this test?

thanks

 

[410Fortune]

Well I build wiring harness for these things so I know what every wire is and where it goes and why. Of course I dont have it memorized (yet) so I have to look it up in the books. But basically there are two wires in the harness that go from the computer directly to the transmission. one is the 3-4 shift solenoid control wire (overdrive) and one is the lock up convertor.

So you can tap into the wire to test it anywhere along it's route. If it's easier for you to remove the kick panel, undo the computer mount, climb in there upside down with a flashlight and locate the proper wire in the loom by color or pin number then thats cool. Personally I think it;s easier to access the tranny wires under the hood, right near your oil dipstick.

Being as stupid as I am I forgot my wiring book that I was suppossed to grab last night so I cant tell you what wire you are looking for.

If your convertor is not locking up you would know it.

Now know this, the convertor is only forced to lock up by the computer, it feels like a gear shift.

Obviously if you are doing 60 mph and you let off the gas, the rpm's drop to 1200-800 (idle) the convertor is not locked up. Then you willhave to speed up the rpm's to "catch up" to the tranny, your not gonna gain any speed again until you get the rpm's backup to 2500-3000. Does that make sense?


Yeah what you are saying is correct, in a sense, like a slipping clutch. If you floor it, then engine wraps up to 4500 rom and it takes forever for the tranny to catch up you could have a convertor problem. However I would check my ATF level first as a low ATF level will cause this. Now know this the convertor works and grips hydraulically up to the point where the computer forces it to completely lock up, so it can be hard to tell.

Now an easy way to check that both your OD and torque convertor are working: start from a dead stop and accellerate (floor it if you are like me) you should count 5 shifts

 

[thedirtyneck]

I think i will try to go under the hood and do it, my voltmeter just has short wires so i thought inside might be easier.

As far as shifting, i have checked this out before and i only get three shifts. And I can move the gear shift lever down into D and it will downshift. These two things tell me that my overdrive is working properly, correct?

If my torque converter was locking up i would have one lockup (shift) between 3rd and OD, and then one more lockup after the shift to OD. Am i thinking correctly here?

Thanks for all your help.

 

[410Fortune]

If you only get 3 shifts there is something wrong.

1 problem could be you are always starting in 2nd gear (kickdown not adjusted properly)

What RPM are you at at 65 MPH? 3800?

Sounds to me like the convertor is not locking up, like you origianlly posted. If you drop it to D from OD and it downshifts then the OD is working. so your RPM's on the highway at 65 should be more like 1500-2000 (gears and tires affect this)

So your thinking is correct, we need to hook up a voltohmeter to the convertor lock up wire and ensure that the EEC is telling it to lock up. I will write myself a note so I dont forget the wiring info tomorrow.....

My buddy Brett (moderator here) has the Ford shop manuals that tell you step by step how to diagnose the A4ld, if you can get your hands on these books you will be able to pinpoint your problem.

How many miles are on your A4LD?

After I converted my truck to an automatic I had similar problems, well I had a ton of problems, from getting the kick down adjusted properly, to a bad EEC (main problem),to having my wiring wrong in the first place. I started troubleshooting by the book, only to find the computer was in fact at fault. Now everything works perfect, of course with my truck it's a little different since it's completely custom..............

the EEC uses signals from all sorts of stuff to control the OD and lock up. The speed sensor is the big one for the OD, if you have the wrong gear in there or the sensor is busted the OD will not work. The throttle position sensor is another big one. The kick down cable has ALOT to do with the tranny functions too, if it is not adjusted right it can cause all sorts of shifting problems....The shifter cable and linkage at the tranny must be adjusted perfectly as well.


Lets start here:

How many miles on the A4LD?
Do you have any other modifications to the engine or drivetrain?
Have you done a visual inspection of the wiring harness, vacuum line, and shift linkage?

 

[thedirtyneck]

Well i just bought my ex about 3 months ago so i dont know much of the history on it.

The truck has 183,000 miles on it but i dont know if the tranny is a rebuild. I will find out tonight or tomorrow though. My dad works with the guy I got it from so he can ask him. I think he was the original owner so he should know.

I have a hypertech chip, problem existed before the chip, custom intake with KKM, 235/75/r15 tires, 3.73 gears

As far as a visual, everythign looks right, as far as I know. The wires are connected to the tranny, nothing is loose. I dont know what the shift linkage is supposed to look like, but it is on there. I recently replaced the tranny filter and fluid.

Ill try to find out as much other stuff about the truck as I can.

 

[410Fortune]

Well if thats the original tranny with 183K miles it;s time for a new one. The overdirve in that thing is worn out completley, guaranteed with that many miles.....

Right now your A4LD has outlasted any other I have ever seen (if it is the original) so the good news is somebody took care of it. Now the bad news is a rebuild is expensive and when they are rebuilt they usually dont last long because the rebuilders use cheapo parts, they dont perform all the TSB's like they are suppossed to and they dont always put them back together with care.
Now if you need a rebuild I can suggest a guy here in Denver who has been building Ford auto trannys for over 30 years, he stands behind his work, he can customize your throttle body, he knows of every upgraded part to use, he performs every TSB they have on the A4LD, can use a custom torque convertor, and basically the only guy I know of in the entire country who knows how to really build the A4LD. Well actually there is a guy in Arizona that I was gonna use, but then a friend of a friend pointed me to Lynn. Oh and if you are worried about shipping cost to CO, dont it would be worth it for you.
Now you can get a remand A4LD for about $1100 with a core trade in if you dotheowrk yourself but if you do some research on this site you will find that going with the cheapest A4LD rebuild you can find is usually where the nightmare begins...........remember Ford built the A4LD since 1984, usedit behind the 2.8, 2.9L and 4.0L engines and they upgraded the internals in them SEVERAL times, so unless you watch them pull it out of a 93+ Explorer you never know what you are getting....

I paid $1400 for my heavy duty rebuild, took him the core, did all the installation work myself, and I got a 25% discount because he is a friend of a friend (I got lucky!!!) I also sat with Lynn through part of my rebuild, and helped whenver I was not "in the way" Man those things are the biggest jigsaw puzzle I have ever seen....


Here's his info:

Contact Lynn
Peformance Transmission
303-288-7377
Denver, Colorado

Tell him Jamie with the BII refered ya.....

just talking to him on the phone you will soon find he's the Ford Auto Tranny man....

Oh and you can ask Brett Grooms (moderator) and Joe Dietz (board member) about the work Lynn does. Basically we consider Lynn our saving grace when it comes to our tranny's, he's almost 70 years old, and One hell of a guy!!!!

 

[MyExpWork]

I just tried that test trick. Going down the freeway at about 60 mph, tapped the brakes and yes the rpms jumped about 200.

So I guess mine is working properly.

 

[thedirtyneck]

Here is a website that gives some good information about torque converters, how they work, and how to test them.

Dead Link Removed

410Fortune.... If you have those schematics with you and can let me kow exactly what wire i need to tap into i would appreciate it. I have to have back surgery tomorrow so i will not be able to do anything about it for a while. Thanks for all your help and if you dont mind ill write you again in a few weeks when I am back on my feet. Thanks again.

 

[jojogirl]

Wow Great link. Answered everything I needed to know! Mine is being replaced and tranny being rebuilt as we speak! $1400.00 + change.. Can you tell me.. I requested a Transgo shift kit.. Good idea?

 

[Glacier991]

Excellent link Dirtyneck.... I may sticky it. And jojogirl... good either the transgo or Superior shift kits are an excellent idea.

I'll move this to the transmissions forum.