slipping transmission

[hubs97xj]

Since when are details relevant in a technical discussion?

 

[scott00tj]

Funny but no one asked what tire size, gear ratio, road conditions and load you are carring in the XJ,...or did I miss that?

Pretty much all stock. '99, 4.0L, AW4, 231, 8.25"/D30 at I think 3.73. Current road conditions are a mix of wet and snow roads, typical Ohio winter. No load other then the driver.

 

[scott00tj]

This weekend I replaced the TPS and adjusted the throttle valve cable and at first I thought things were fixed. I put about 50 miles on the XJ and thought the issue was fixed.

Today the issue came back and by the time I got home it was really being a pain. It's as if I'm bumping the shifter from drive into neutral and then back when at 40-55 mph.

Something else I noticed today, or could just be me worrying to much, is it seems when this is happening and I'm going slower such as on city streets the RPMs are higher then they are normally are compared to the past. The gas miliage is suffering too now because of this, about 2 - 3 mpg.

 

[scott00tj]

Could I be seeing a problem with the torque converter staying locked up? I was reading THIS article and in the 4th paragraph it said one of signs of this could be the random shifting I'm seeing.

 

[Redsnake]

Any updates or solutions for you? I'm in the same boat as you and sounds like the same problems. When my transmission heats us ('96, 4.0, AW4, NP231 w/ 247K miles) the RPMs start climbing and my speed drops off.

Today as I pulled into my neighborhood I was hitting about 2200 RPMs and coasting down the road in 4WD. This huge snow storm we've had in OK has had me running around in 4WD for about a week straight. More than I ever have in the past. I did notice when I got home that my trany fluid was a bit overfilled. I drained about 1.5 qts and now it's at the low end of the 'check' bracket. It also smelled burnt but still looks pink. I just did a 3 qt tranny change about 4 months back so the fluid still looks good. I also checked my cable adjustment as mentioned here and it was good.

I REALLY don't want to pull the transmission and swap it out w/about 12" of snow and ice around. Not my idea of a pleasant experience.

 

[scott00tj]

Any updates or solutions for you? I'm in the same boat as you and sounds like the same problems. When my transmission heats us ('96, 4.0, AW4, NP231 w/ 247K miles) the RPMs start climbing and my speed drops off.

Today as I pulled into my neighborhood I was hitting about 2200 RPMs and coasting down the road in 4WD. This huge snow storm we've had in OK has had me running around in 4WD for about a week straight. More than I ever have in the past. I did notice when I got home that my trany fluid was a bit overfilled. I drained about 1.5 qts and now it's at the low end of the 'check' bracket. It also smelled burnt but still looks pink. I just did a 3 qt tranny change about 4 months back so the fluid still looks good. I also checked my cable adjustment as mentioned here and it was good.

I REALLY don't want to pull the transmission and swap it out w/about 12" of snow and ice around. Not my idea of a pleasant experience.

I haven't been able to track down the issue. I'm still having the same problem. It's really starting to drive me nuts. As far as suggestions left to try I still have to look at the NSS and seeing if its clean. I have this feeling its going to be a big pain in the butt so I've been putting it off.

At this point I'm real close to pulling the trigger on just getting a whole "new" AW4..... but its colder then hell here now and I don't feel like a swap right now. Kind of the Armageddon style of automotive maintenance, but that may not be the issue, which is the 1 thing holding me back.

 

[Redsnake]

I feel ya man. We've got about 2' of snow outside in the driveway and I don't want to mess w/my tranny right now. I'm going to do a search for a 'new' AW4 myself. I'm not sure I want to tackle swapping them out myself or take it to a shop. Depends on the cost and availability.

I'll keep this post updated if/when I find out something.

 

[XJ4JOE]

I just had this happen with the used transmission I we put in a 96 XJ. I had only driven it maybe 150 miles has fresh oil and filter. ATF-4 though which reading other threads could be an issue but fluid level seemed fine cold but when I checked it hot it was a little over filled. I haven't tried any of the adjustments mention previously but hopefully they work or I just wasted a few $$$ replacing my old transmission.

 

[scott00tj]

I just had this happen with the used transmission I we put in a 96 XJ. I had only driven it maybe 150 miles has fresh oil and filter. ATF-4 though which reading other threads could be an issue but fluid level seemed fine cold but when I checked it hot it was a little over filled. I haven't tried any of the adjustments mention previously but hopefully they work or I just wasted a few $$$ replacing my old transmission.

I replaced the fluid and filter in my AW4 as well. Each day when I get home from work (about 20 min drive) I check the fluid level. It's high, but not past the full mark. I would really like to have the fix just be a slight drain of fluid. My AW4 did start this issue before I changed the fluid though.

 

[scott00tj]

Before I jinx myself I have to say I'm not ready to call this issue corrected. I want to put a few more test drives and more miles on my XJ before I can call it fixed.

Today I replaced the brake switch. It was only $12 at AutoZone and I figured it was worth a shot. It's a really quick 5 minuet swap. After doing so I drove my XJ around for about 20 minuets going up and down a stretch of road where I can run 45 - 50 miles an hour for about 5 minutes at a time. This let me drive at the speed range where the issue presented itself. So far so good. I did not notice the shifting problem I've been dealing with. I noticed that my mpg on my overhead console went up 1.5mgh while running this test. These are encouraging signs, but like I said, I'll more more after some more seat time.

 

[bdahlg]

Why would the brake switch fix anything to do with the transmission? it's function is to control the brake lights and shut off cruise control if equipped.

 

[scott00tj]

Why would the brake switch fix anything to do with the transmission? it's function is to control the brake lights and shut off cruise control if equipped.

The TCU of the transmission gets a signal from the brake switch. Pin 23 if I recall correctly. I am by no means a mechanic, just a weekend warrior, I could be 100% off with this most recent test. I was also having an issue with the cruise control not working until I pulled up on the pedal so it was a fix for that too if nothing else.