AW4 Problems

[Dzimm]

I looked for my old post about this but couldn't find it so I'm just gonna start a new one.  My 98 XJ AW4 has been slipping/clunking in 4th gear for a while.  I can accelerate to whatever speed I want in 3rd gear but as soon as it shifts to 4th, I cannot accelerate without it slipping but I can hold speed just fine.  A couple days ago it got to the point I unplugged the computer and just drove it with 1,3, and 4th gear manually and have really been looking into this issue.  

 

Here is what I know.

- With the TCU unplugged, it drives fine in 1,3 and 4th with no slipping at all.

- With my TCU from my MJ project makes it slip MUCH worse than the original TCU.

- When accelerating moderately heavy in any gear with the TCU plugged in, it hesitates like I'm not getting fuel or something and I can hear a jingling noise from the rear end.

- When accelerating heavily in any gear with the TCU unplugged, it sometimes hesitates and makes the noise like above but not as frequent.

- I have done 1 fluid change on the trans and am planning on doing a few more.

- I have already changed the TPS with my spare one and it made no difference.

 

It seems to me that I likely have 2 problems that may be linked somehow.  One being that the Trans has some sort of electrical issue that I am not sure how to proceed with, and two being that my fuel pump of only 1.5 years is likely having issues.

 

I would really appreciate any input on this as it is very frustrating and being my DD I really don't have the ability to just tear everything apart.

:wall:  :wall:  :wall:  

[MeanLemons]

Ever adjusted theTV linkage?

[Dzimm]

Ever adjusted theTV linkage?

Yes I have done that.  Would that affect 4th gear though?

[omega_rugal]

 

Ever adjusted theTV linkage?

Yes I have done that.  Would that affect 4th gear though?

 

 

maybe it`s not "slipping"more like  it`s kicking down to 3rd gear as soon as it shifts to 4th... anyway if shifting manually is ok then the TCU is the culprit...

[Dzimm]

 

 

Ever adjusted theTV linkage?

Yes I have done that.  Would that affect 4th gear though?

 

 

maybe it`s not "slipping"more like  it`s kicking down to 3rd gear as soon as it shifts to 4th... anyway if shifting manually is ok then the TCU is the culprit...

 

But it shifts into 4th gear and I can hold a constant speed, its only when I am accelerating while in forth gear.  And yeah I was thinking the TCU as well but how could I have 2 TCUs that cause the exact same symptoms but 1 worse than the other.  Is there any other point along the electrical system I should be checking or is it one of those, follow and inspect every inch of wire kind of things.  I was also thinking maybe a bad solenoid, which could make sense if it is doing like you said and actually downshifting and then quickly upshifting again.  Is there a good way of testing solenoids without dropping the trans pan?

[ScottJeep]

It can be done via the connectors to the TCU. 

 

http://comancheclub.com/topic/34253-aw4-transmission-computer-testing/

http://mikestrawbridge.com/blog/2011/09/aw4-troubleshooting/

[Dzimm]

It can be done via the connectors to the TCU.

 

http://comancheclub.com/topic/34253-aw4-transmission-computer-testing/

http://mikestrawbridge.com/blog/2011/09/aw4-troubleshooting/

This is very helpful thanks! That CC thread is making me more confident in a bad solenoid. I will now be doing voltage testing.. Yay...