• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Aw4 slipping after 20 minutes?

eyebeatbadgers

NAXJA Forum User
Location
Nashville, TN
I'm running an AW4 behind a VW tdi engine in my YJ wrangler. Manually controlled with Winters Shifter and Radesigns controller. Engine puts out 300+ lb. Ft of torque

Put 5k miles on it successfully. One day on commute home, tcc came out of lockup on the highway. Odd because tcc lockup is on a switch. After letting off gas a little it went back into lockup.

Next day trans started slipping after 20 minutes of working fine on the interstate. Started after sitting at red light. Trans temps stay under 100F at all times. Still shifts through all 4 gears no problem, just slips to the point I can't go over 30mph.

I pull over to check fluid level etc, no problem. No leaks, all seems normal. Gets a bit worse over next mile. I pull over and turn off engine for 10 minutes, afterwards trans acts fine.

Same scenario next day on commute to work, runs perfect for 20 minutes, then gets slippy after highway run and then red light. Trans temp never goes over 100f before it starts slipping.

Ideas? I feel like maybe torque converter is failing? I'm probably going to just replace entire trans again, just would like a diagnosis of failure.
 
I would start by changing the filter and making sure you use the correct ATF before making any determinations.
 
BTW, how are dealing with the trans TV cable?
 
Another trans is just a bit drastic at this point. As suggested, start with the cheap and easy stuff. Make sure all the wires are in good order with no damage, short circuits or open circuits, or faulty connections, and perform a 100% fluid change using the specified Dexron-III/Mercon fluid. Test the solenoids.
 
That's not that much torque, specially for the AW-4. Things to consider though since it produces it all at a very low rpm.
You may need a lower lock-up rpm torque converter......
You may need a cam on the tv cable to bring in earlier......
 
How much pressure does the aw4 make? Is pressure rising with throttle input.

I'd do filter change dumping fluid from converter to.

Make sure all adjustments are to spec. Top it off with tractor transmission fluid like jd30 or chevron thf1000.


Do not continue to drive if its slipping.

Wire tv lever to ensure it's open at 70-100% of its travel. This will creat higher rpm later shifts possibly harsh shifts but will ensure that transmission is producing more pressure under throttle.

Good luck.

I have a aw4 kicking around thought about playing with it but know very little about them. I saw I could run it with a RAD's shifter like your doing with the winters
 
Fluid and filter have 5k miles on them, still pink in color. Hard to believe that's the problem.

The TV cable has been pulled to about 75% out and zip tied in place there. That may be my issue. Kinda forgot about doing that until it was mentioned. Could have burned up clutches perhaps?

Solenoids are fine, they were all checked a couple hundred miles ago when one failed.
 
I'm interested in the aw4 so did some reading.
They don't seem to have the aftermarket support that trannies like the 47re in my truck have. But look to be able to be rebuilt fairly inexpensive and up holding capacity considerably

https://www.naxja.org/forum/showthread.php?t=1055170

That's the only issue, getting good parts for it. The trans itself is just like any automatic otherwise.
 
The TV cable has been pulled to about 75% out and zip tied in place there. That may be my issue. Kinda forgot about doing that until it was mentioned. Could have burned up clutches perhaps?

You need to duplicate the stock throttle body's TV cable attachment, so it opens more as the throttle opening is increased, reaching full pull at full throttle.
If Toyotas engineering thought the AW4's variable TV wasn't necessary, they would have saved the money and eliminated it.
A 75% TV opening, at full throttle, isn't enough to provide full pressure to the servos and could have caused the friction material to wear away, with extended use.
 
But more important is the fact Toyota's turn better than 6000rpm which means the valve is calibrated for that vs the TDI which has about a max of 3000rpm. This means using a cam to adjust for a much lower initiation and not over pull the cable.
 
I agree with this.
Autos in gas trucks and cars turn higher rpm. The creat mre pump volume that's why diesel trucks need higher idle pressure exspecly when mdded.

My 47re factory idle pressure is about 50-55 psi. And 90-100 at wide open throttle.

My tranny now makes 100 at idle and 165ish wide open..

I am not sure it needs t be variable TV arm but it kinda is at least on the 47re because the arm sings in arc. I have messed with springs and arms because I have slac at idle because of were I have my tv lever stop set at. So my tv valve doesn't move till I hit about 1/4 throttle.
This has not been a problem because I make mre than enough power t hold 400hp and who knows how much tourqe.


Since your aw4 is slipping its spreading clutch material throughout and possibly clogging the filter reducing transmission pressure intensifying the problem.

If your not wanting to change fluid and filter I would try dropping a couple bottles of friction modifiers in it. This will not fix worn damaged parts but will most likely show and instant increase in holding power because it will make what's still left hold better in both lock up and fluid coupling.

Ford f fluid will also work well and is a red fluid tractor transmission fluid is what I run in my 47re I get lower temps and quicker firmer shifts compared to atf+4.
I would not run cheap tractor transmission fluid from farm and ranch stores. It may not have the additive package that higher quality johndeer or Chevron oils have.

I also wonder if your transmission is going into limp mode because of a heat issue or pressure transducer malfunction.

Even new sensors go bad. I just replaced a borgwarner upgraded pressure sensor in my tranny due to going into limp mode. Wich causes 2nd gear starts..

Tractor transmission fluid may make it so you get a few more years out of that aw4 before new clutches and tourqe converter are needed. Or adding friction modifiers. Some people are afraid to ver away from manufacture suggested oils.
 
My 47re factory idle pressure is about 50-55 psi. And 90-100 at wide open throttle.
Since your aw4 is slipping its spreading clutch material throughout and possibly clogging the filter reducing transmission pressure intensifying the problem.


Ford f fluid will also work well and is a red fluid tractor transmission fluid is what I run in my 47re I get lower temps and quicker firmer shifts compared to atf+4.
I would not run cheap tractor transmission fluid from farm and ranch stores. It may not have the additive package that higher quality johndeer or Chevron oils have.

I also wonder if your transmission is going into limp mode because of a heat issue or pressure transducer malfunction.

Even new sensors go bad. I just replaced a borgwarner upgraded pressure sensor in my tranny due to going into limp mode. Which causes 2nd gear starts..
.

I would think the AW4 used in XJ's would be Factory calibrated for the 4.0's RPM range. Comparing it to a 47e is an apples to oranges comparison.
The VW TDIs I have drive have power range not too different than the 4.0, they are not high reving engines.

AFAIK, the AW4 does not have a temperature sensor or a pressure sensor .
Older AW4s just have a the output speed sensor, while 1997+ AW4s have a second, input speed sensor .
I would be cautious about running tractor fluid or anything else beside Mercon III. Using it as an last attempt to temporally fix the trans is OK, I guess, but if needed, it's only going to be a band-aid.
 
The fluid things we can debate for years. Been working great for me for over 100k. Offcourse in different application.

Does appear the aw4 would be suited for the tdi.

As much as the OP says it was slipping I'd consider anything a bandaid at this point. If it is in fact slipping. It should show higher temps than 100 degrees if its slipping.

If temp gauges is reading correctly I'd also exspecly higher temp while not slipping.
 
I would think the AW4 used in XJ's would be Factory calibrated for the 4.0's RPM range. Comparing it to a 47e is an apples to oranges comparison.
The VW TDIs I have drive have power range not too different than the 4.0, they are not high reving engines.

I would agree with this - I have an 02 TDI (so the ALH motor), and the RPM range and powerband is not that different from the 4.0; redline on the TDI is around 4600-4700 RPM to the 4.0's 5200(approx), so if you were able to simply replicate the TV cable mechanism from the 4.0 you'd probably be pretty close to where you'd need to be

You might want to head over to www.tdiclub.com and post up in the conversions sub-forum - there's been a few Jeep conversions there (XJs, TJs, MJs).

Here's one thread about a TDI swap using an AW4: https://forums.tdiclub.com/showthread.php?t=455693

Sounds like the guy went AX15, but there's a post by a vendor name of "evguy1" who says he knows of folks who've made the AW4 work with a TDI - might be worth reaching out to him, his website's in his sig...
 
Fluid and filter have 5k miles on them, still pink in color. Hard to believe that's the problem.


Solenoids are fine, they were all checked a couple hundred miles ago when one failed.

What type of trans fluid is in it ? Lots of XJ Cherokee owners report transmission slippage when ATF+4 is used instead of the specified Dexron-III/Mercon fluid. IMO Dexron VI is not a suitable substitution for Dexron-III/Mercon in the AW-4.

The solenoids test fine, or you think they are fine ? The last repair or modification is always a primary suspect when new symptoms arise.
 
Last edited:
But more important is the fact Toyota's turn better than 6000rpm which means the valve is calibrated for that vs the TDI which has about a max of 3000rpm. This means using a cam to adjust for a much lower initiation and not over pull the cable.

An ALH TDI making 300 lb-ft will be fueled to near 5000rpm anyway. Not much different than a 4.slo
 
I appreciate the ideas from everyone. I assume my cheap and quick way of dealing with the tv cable is to blame here, I didn't intend for it to be left that way, but you know how that goes.

I'm going to replace fluid and try a little bandaid fix, and attach the tv cable properly. I can find good AW4 trans for around 100 bucks pretty often, so not a huge deal to replace.

For posterity's sake, the fb group tdi swapped trucks has a files section with good info on how to rig up the tv cable to a vw gas pedal.
 
Back
Top