AW4 Shifting / Overheating Issues in XJ Buggy

Alright, so after doing a bit of wheeling last month, I need to get some issues addressed with my setup, so all input would help .

So in my build (yeah I know my pictures aren't working), I connected up my own gate shifter to the shift lever on the side of the AW4.

However I'm running into some issues.

- Tranny gets way too hot just crawling (gauge sits at 250°+)
- I think I may not be actually getting 1st gear? (according to Flores, who seems pretty familiar with the AW4 )
- 3rd gear is all the highest I can go (RPM's are getting up there doing 40MPH or so).

Now, I know part of this is due in fact to:
- Torque converter not locking up, thus creating excess heat
- If I'm not getting 1st (which I'm thinking i'm not), then the heat build up with the couplers in second makes sense
- I run manual brakes, so the transmission isn't seeing the resisted signal that the brakes are/aren't on.

So...

How do I go about fixing these issues? I'm not remotely electronically dumb, but transmissions aren't exactly my forte :laugh:

Essentially I'd like to be able to cruise it at 40-50mph, as well as crawl like normal.

I don't want to be doing manual shifting, I'd like to use the AW4 as "normally" as possible.

Thoughts? Fixes? How to's?

Have you tried removing the shifter and manually shifting at the trans?

trippled said:

Have you tried removing the shifter and manually shifting at the trans?

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Not sure what you're getting at here? The gate shifter I have is manually attached to the trans shifter arm as was the cable shifter in the OEM shift setup.

Basically are sure it has enough throw to fully aengage first? My last 99 wouldn't like to engage m1 and id have to slam the shifter down to get it to go. It recently got totaled tho so never had time to mess with it. Any trouble codes?

trippled said:

Basically are sure it has enough throw to fully aengage first? My last 99 wouldn't like to engage m1 and id have to slam the shifter down to get it to go. It recently got totaled tho so never had time to mess with it. Any trouble codes?

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Oh yeah, it definitely does. I can easily feel it engage each detented position.

If you're in low-low (~7.2:1) in the t-cases and go from D to 1-2...it will want to throw you through the windshield

I've got check engine codes at all times (since my rig is missing a lot of OEM stuff).

Last time we checked, nothing related to the trans.

Bigger trans oil cooler. AW4s like to run hot, especially if you remove them from the factory radiator heat exchanger. If you are only running a stand alone cooler, something this is what you will need to keep the trans temp in check.

http://www.kartek.com/Product/1022/CBR-Large-Off-Road-Oil-Cooler.aspx

squirrel80 said:

Bigger trans oil cooler. AW4s like to run hot, especially if you remove them from the factory radiator heat exchanger. If you are only running a stand alone cooler, something this is what you will need to keep the trans temp in check.

http://www.kartek.com/Product/1022/CBR-Large-Off-Road-Oil-Cooler.aspx

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That may be true.

I had thought my current setup would have been plenty:



There's a 7" Derale Fan mounted as a puller on the bottom, rated for 1500CFM.

What Tcase,axle gearing and tire size are you running?
The stock cooler in the Rad is very small and just about any aftermarket stand alone cooler is better. And it should work even better with its own fan and mounted away from the hos rad.

But really knowing the rest of the drive line and tire size is key to this problem. The AW4 is a great little trans but like people have posted its a heat monster. Its really due to its small converter.

Mach2nh said:

What Tcase,axle gearing and tire size are you running?
The stock cooler in the Rad is very small and just about any aftermarket stand alone cooler is better. And it should work even better with its own fan and mounted away from the hos rad.

But really knowing the rest of the drive line and tire size is key to this problem. The AW4 is a great little trans but like people have posted its a heat monster. Its really due to its small converter.

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231/D300 doubler (1:1, 2.62:1, 2.72:1, 7.2:1), 5.38's in the axles, 40" tires

My thoughts were the same.

Essentially as far as solving the heat issue, I'm thinking about going all out (i.e. overkill).

I'm thinking about buying a larger stacked plate cooler, larger fan, and mounting back behind the driver's seat under the action packer.

It's either that or buy a smaller plate cooler and swap it for the tube and fin I currently have and hope the efficiency pickup would do the trick.

I'm thinking the former of the two would be better if I'm going that far to swap things up.

Going to get some measurements tonight.

First, very nice rig!!!

It sounds like you may have multiple trouble spots and perhaps still sorting all of this out. It took me awhile, as well.

I agree with Squirrel80. I added a similar trans cooler after seeing 230*+ pre-running Barstow race courses in mid-August. Afterwards (+AMSOIL) , I can keep my trans at 180* or below. Typically, trans coolant temps are ~160* unless under heavy load.



Mine - 4.0L + AW4 + 231 w/4:1 + Klune V 2.72:1 + 4.56:1 in the axles + 33" tires, while utilizing Rory's Baja II manual shifter setup. Everything with Rory's setup is working, as expected. Including getting first and lock-up. Perhaps double-check the installation/wiring instructions on his website, as it seems you're still having some manual shifting issues.



I kept the stock trans cooler, as well.



Also, perhaps worthy of noting here is that I had a catalytic converter with ~10k miles on it fail (rattling at startup) that was affecting my engine coolant temp and performance, which I recently replaced.
Lately, my three little ones and I have been working to improve heat shielding for the undercarriage. Shields for both the converter and the muffler lowered floorboard temps directly above the muffler by ~150*. I'm now considering adding more shielding to keep heat away from critical drivetrain components.

JeepityJeep said:

First, very nice rig!!!

It sounds like you may have multiple trouble spots and perhaps still sorting all of this out. It took me awhile, as well.

I agree with Squirrel80. I added a similar trans cooler after seeing 230*+ pre-running Barstow race courses in mid-August. Afterwards (+AMSOIL) , I can keep my trans at 180* or below. Typically, trans coolant temps are ~160* unless under heavy load.

Mine - 4.0L + AW4 + 231 w/4:1 + Klune V 2.72:1 + 4.56:1 in the axles + 33" tires, while utilizing Rory's Baja II manual shifter setup. Everything with Rory's setup is working, as expected. Including getting first and lock-up. Perhaps double-check the installation/wiring instructions on his website, as it seems you're still having some manual shifting issues.

I kept the stock trans cooler, as well.

Also, perhaps worthy of noting here is that I had a catalytic converter with ~10k miles on it fail (rattling at startup) that was affecting my engine coolant temp and performance, which I recently replaced.
Lately, my three little ones and I have been working to improve heat shielding for the undercarriage. Shields for both the converter and the muffler lowered floorboard temps directly above the muffler by ~150*. I'm now considering adding more shielding to keep heat away from critical drivetrain components.

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Thanks!

I think I've decided to try and tackle the cooling issue by just going "overkill".

Going to go ahead and get the derale 13870, and mount it in the rear.

I also looked at Griffin and CBR, but I think those are going to be just more $$$ than anything when it comes to the AW4.

Now, to figure out / fix the other issues...

Have you tried just verifying computer function? Since you pulled so much wiring and stuff checking power and grounds to the trans computer might be worthwhile. Also checking solenoid command while your driving in od position and making sure the gears are correct (think you can just use some test lights).

Have you tested the solenoids?

I would make sure you can get 1st gear before upgrading the cooler though. The tranny would definitely be working substantially harder in 2nd even with the doubler in play.

trippled said:

Have you tried just verifying computer function? Since you pulled so much wiring and stuff checking power and grounds to the trans computer might be worthwhile. Also checking solenoid command while your driving in od position and making sure the gears are correct (think you can just use some test lights).

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Some of that is what I'm working on trying to get help figuring out

Boostwerks.com said:

Have you tested the solenoids?

I would make sure you can get 1st gear before upgrading the cooler though. The tranny would definitely be working substantially harder in 2nd even with the doubler in play.

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I'm thinking about pulling the solenoids and testing them. I need to drain the pan and do a fluid swap anyhow. As well I want to pull the gauge bung and verify it's reading right. From there I can pull the solenoids out and do a bench test on them. Luckily they're cheap.

Alright, so bringing this back from the dead.

I never swapped in another cooler/fan, as I want to make sure I've got the other issues solved first, and see if that remedies it.

I pulled the drain pan plug the other day, the fluid didn't appear burnt or discolored, seemed just fine.

I know I'm not getting the TC lock if for nothing more than I no longer have the brake light switch, so it's reading open at all times, and not getting the signal it should that the brakes are disengaged. It would be nice if all I needed to to was just wire in an ignition hot source to the brake light switch sense input wire on the TCU

A buddy of mine (zluster) has a DRBIII reader. I'm going to see about having him hook into the OBD2 and taking a drive to see if/what/when which solenoids are firing. Hopefully that should tell me if I'm getting first gear.

I'll be pulling the tranny temp bung as well to make sure it's reading properly.

So that leads me to:
1.) I've done a bit of searching around...but can't find this (I've got an FSM as well for wiring diagrams and pinouts): What all tells the TC solenoid to fire? I know it needs 12V across the brake switch sense...but what else? Obviously it's not on any time the brake is disengaged, so there are other inputs letting it know to be disengaged. Unfortunately, the FSM doesn't show (as far as I can see) the connections within the TCU, just inputs and outputs.

Most searching I do leads to the brake light switch sense, since most people haven't eliminated that system as I have.

I guess in all reality I could just put in a switch to feed the solenoid power, but it would be a hair bit nicer for it to just do it on it's own, instead on having to turn it off/on as I putz around :laugh:

I could be wrong, but I thought the brake input was only to unlock the tcc if it was already locked. Other inputs would be coolant temp, speed, load (map and tps) to name a few. Hook it up to the drb like you said tho and see what's going on.

Brake switch unlock converter, as does letting off the gas. As designed TC locks cruising on flat ground above 45mph in 3rd or 4th. It's not intended to be used going slow when wheelin'. Verify TCU is working correctly by checking the solenoid wires for power at the appropriate times. Better have help for this so you don't crash while driving and checking for power.

trippled said:

I could be wrong, but I thought the brake input was only to unlock the tcc if it was already locked. Other inputs would be coolant temp, speed, load (map and tps) to name a few. Hook it up to the drb like you said tho and see what's going on.

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R.DesJardin said:

Brake switch unlock converter, as does letting off the gas. As designed TC locks cruising on flat ground above 45mph in 3rd or 4th. It's not intended to be used going slow when wheelin'. Verify TCU is working correctly by checking the solenoid wires for power at the appropriate times. Better have help for this so you don't crash while driving and checking for power.

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If the brake like switch is normally closed, and normally open disconnects the TC, then wouldn't I still not get the TC to lock, as it needs the normally signal (as well as others) to lock?

I'll get the DRB3 hooked in and we'll make sure the solenoids can fire, and go for a drive to see them firing.

Now, say we go for a drive, and like normal the rig tops out at ~45...and there's no signal of the TC solenoid firing. Where would I need to go from there?

Seems like at that point, possibly just wiring in a switch will have to suffice.

TCU needs several inputs for all shifting including TC lock. TC lock is accomplished by supplying 12V+ to the TC solenoid.
If you changed gearing and tire sizes then this will affect when or even if the TC will lock up. Remember its looking for stock rpm, speed and throttle input characteristics, plus more.

R.DesJardin said:

TCU needs several inputs for all shifting including TC lock. TC lock is accomplished by supplying 12V+ to the TC solenoid.
If you changed gearing and tire sizes then this will affect when or even if the TC will lock up. Remember its looking for stock rpm, speed and throttle input characteristics, plus more.

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The speedo was changed to reflect a pretty near stock setup. Speedometer reads just fine and last I checked was pretty accurate.

What I'm trying to find it...what are all those inputs.

It's looking more and more like it's not worth the effort, and to just install a TC lock switch in like others have.