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AW-4 shifting problem: won't shift past 2nd

Char-Broil

NAXJA Forum User
Location
PA
As some of you know, I just got an 87 XJ from my uncle. It has the 4.0, aw-4, 242, and 133k mi. I powerwashed the engine compartment and drivetrain this weekend before driving up to school. the engine was pretty nasty so i used engine brite. Now since i washed it the trans only shifts into second at about 4200 rpm. It doesnt shift again after that. I thought maybe something was just wet, so i let it sit for a day or so, and it actually worked the next time i drove it, shifted fine. But now it has done it the last 2 times i've driven it, only goes into second. is the TCU fried? is there a tcu? is my kickdown cable screwed up? i dont even know what alll could affect it. I have the ax-15 in my other jeep and i'm seriously considering dropping one in this xj, i already don't enjoy the auto's gimmicks. hopefully someone can shed some light on this so i can drive home this weekend and get more than 4 miles to the galon. thanks
 
change the fluid and check the filter would be my first guess there is TCU for the aw-4 but i'm not very experienced on it but there are a lot of guys on here who know the aw4 in and out id just search around and ask them
 
the tcu is under the steering wheel in the car. there are adjustments on the cable. but its not that. did you get the tps wet. they don't like water. so my guess is that its that. it controls the ecu and tcu. when mine went my torque converter locked up at random speeds.
 
If you washed the engine compartment i would check the TPS sensor, its involved in tranny shifting and really be effected by water. Dry it and clean the connector if not i would replqace it.

pete
 
The TCU on an 87 is under the dash on the passenger side. There is a fuse in teh wiring harness to it that may be easier to pull than getting your hands up there to pull the connector off. The tranny cable doesn't affect the shift points, btw.

I'm voting for a water logged TPS as that is pretty common after the careless use of a pressure washer. Try unplugging the TPS and see what happens. Swapping in an AX15 for an AW4 is a step down in reliability, imho.
 
Thanks for all the help guys, i will pull apart the TPS and if that doesnt fix it i will mess around with the TCU.

I would like a little further explanation on this however...

lawsoncl said:
Swapping in an AX15 for an AW4 is a step down in reliability, imho.

Can i just say that i have a 94 with over 215,000 on it and 65k of that is on oversized tires i've only replaced the clutch once and it was stock when i cracked it open. I've never replaced the slave cylinder or had any complaints about the trans. I enjoy that it is a non computer or electronically controlled device that will never leave me stuck in a gear when there is nothing mechanically wrong. there's just something wrong about not being able to put your transmission in teh gear you want because a computer "thinks" it is best to be in another gear.
i also have a friend who has a lot of miles on his ax-15 with not a single problem and still the stock clutch. I have been to a jeep shop around here that works with a lot of XJs and they much prefer the ax-15 because it is a stronger transmission. i understand people prefer autos and theres nothing wrong with that. but i dont see that they are very reliable.
 
The AW-4 will outlast several clutches every time, unless your a very easy and good driver then is a draw.
Oh and the Jeep shops don't get as much work on them and do find manuals easer to work on.
Very few shops can afford to keep a Auto tech working so most just shop Automatic work out.
 
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Would you consider doing burnouts with 31's an easy good driver?

Aw-4 is a good tranny, but when it comes to reliability...
I use the same idea as my door cranks.
when the key is off i can still roll the windows up.
for me...
one less thing to worry about, and if somthing goes wrong with it.
it's the clutch. none of this guessing.

If my jeep stops shifting correctly its usually because my wife is driving...
 
Did you powerwash underneath as well? Check the connectors on the transmission harness and NSS.

As for the swap. It's your buggy, do what you want. I know several other XJ with 200K+ on AW4s. My '88 has 170K and has never failed.
 
i did wash underneath, and i checked the connections didn't see anything amiss. nss wouldn't affect shifting, just reverse lights or starting the engine i thought. i agree the aw-4 is a about as good as medium duty autos come, but i still prefer a manual with metal gears that don't require any fluid couplers to lose power and torque through. and i've not known to many clutches to just fail and leave a vehicle sit, you can usually tell when it is going and replace it. well it's been raining like crazy here and i have not gotten under the hood of my soaked jeep yet....
 
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