NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old August 12th, 2017, 12:56
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Bad Transmission?

So I just got back from a long road trip. I noticed while driving up the mountain roads the Xj was bucking. I was not manipulating the pedal to keep it in a higher gear and I have been driving these Jeeps for many years now. They dont buck, at least not that I have ever managed to make it do and definitely not at 45 mph. I have not managed to get it to buck on the lower gears but in 4th if I am on any kind of incline it bucks. I checked the fluid and its at a good level, and the color is not red but its not black. Due for a change yes but not harmful for the transmission yet. Any way of fixing this problem? I need to avoid a new trans as much as possible. I have the ability but dont have the time or tools to swap it.

Oh I checked the transmission fluid after the vehicle had sat overnight. I thought that would be the best way of doing it. If thats the wrong way let me know.
Reply With Quote
  #2  
Old August 12th, 2017, 13:03
JohnX's Avatar
JohnX JohnX is offline
Sarge <3 Ben
 
Join Date: Nov 2004
Location: Rancho Cucamonga CA
Posts: 8,767
Re: Bad Transmission?

AW4s are pretty solid. Drop the pan, change the filter, clean the pan, reinstall, and fill with the correct fluid.


However...are you sure it isn't a misfire? Ignition system misfires initially show up under high load in higher gears. 4th gear climbing a hill without downshifting and at low (under 3k) tpms is a very likely time to notice a misfire.
__________________
88 MJ on 40's. 98 XJ on 35's. 98 Dodge, 52psi of boost. 94 Miata LS4. 70 Buick GS455. 01 Harley, been to 46 states. 05 KTM, 576cc. 06 Husky, girls need bikes too. 2011 R6, girls need sport bikes too. 99 Toyota Avalon, daily. 97 Miata, girls apparently need miatas too.
And everything fits in the garage!
Quote:
Originally Posted by mako my day View Post
Johnx is #1
Reply With Quote
  #3  
Old August 12th, 2017, 13:05
Yzzerdd Yzzerdd is offline
NAXJA Forum User
 
Join Date: Jun 2017
Location: North Attleboro, MA
Posts: 34
Re: Bad Transmission?

Checked after it sat? To check tranny fluid, in any auto, first get it to operating temp. Then, while at a stop, shift it from park, through all the gears(allowing them to engage), then back. Pull the dipstick, wipe it, stick it back in, check it.

I'm not an expert on the AW4, I'll let someone else chime in there.
Reply With Quote
  #4  
Old August 12th, 2017, 13:07
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Re: Bad Transmission?

Does not seem like a misfire. I derived the timing on that engine myself, has a new engine. The only sensor I replaced is an o2 though. Are you suggesting that the ignition coil may be going out? Also worth mentioning I have never actually reached 3k on my Jeep so its always at these low rpms
Reply With Quote
  #5  
Old August 12th, 2017, 13:08
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Re: Bad Transmission?

Quote:
Originally Posted by Yzzerdd View Post
Checked after it sat? To check tranny fluid, in any auto, first get it to operating temp. Then, while at a stop, shift it from park, through all the gears(allowing them to engage), then back. Pull the dipstick, wipe it, stick it back in, check it.

I'm not an expert on the AW4, I'll let someone else chime in there.
I will try that thank you. Definitely did it the wrong way
Reply With Quote
  #6  
Old August 12th, 2017, 13:16
Yzzerdd Yzzerdd is offline
NAXJA Forum User
 
Join Date: Jun 2017
Location: North Attleboro, MA
Posts: 34
Re: Bad Transmission?

Quote:
Originally Posted by alexgalexg View Post
I will try that thank you. Definitely did it the wrong way
I didn't mention it specifically, but you leave the Jeep run while you check the tranny fluid.
Reply With Quote
  #7  
Old August 12th, 2017, 15:14
Jeep Driver Jeep Driver is offline
NAXJA Forum User
 
Join Date: Jun 2016
Location: Parrottsville
Posts: 617
Re: Bad Transmission?

O2 sensor. Yeah I know you say you replaced it................
Reply With Quote
  #8  
Old August 12th, 2017, 15:50
JohnX's Avatar
JohnX JohnX is offline
Sarge <3 Ben
 
Join Date: Nov 2004
Location: Rancho Cucamonga CA
Posts: 8,767
Re: Bad Transmission?

Quote:
Originally Posted by alexgalexg View Post
Does not seem like a misfire. I derived the timing on that engine myself, has a new engine. The only sensor I replaced is an o2 though. Are you suggesting that the ignition coil may be going out? Also worth mentioning I have never actually reached 3k on my Jeep so its always at these low rpms
An ignition induced misfire does not have anything to do with the timing, it actually means that one of the sparks is not making it to the spark plug or not jumping the spark plug gap because it is too weak. This can be caused by a loose plug wire boot at the plug, a loose plug wire boot on the distributor cap, a carbon track down the porcelain of the plug, a fouled spark plug from oil burning, a broken spark plug wire or damaged spark plug wire, a bad distributor cap or rotor, bad distributor shaft bearings, etc, etc, etc, the list goes on.

It's is easiest to diagnose if you've felt it before. You can intentionally create a high load by letting it shift into high gear, then steadily increase throttle pressure (not so hard as to cause a downshift). Usually this is done going up hill.

If you have a misfire it will feel like the engine shuts off instantaneously, and then comes right back to normal. You feel that "sputter" repeatedly if you keep the load high. Either downshifting to raise the rpm, or backing out of the throttle will cause the misfire to stop and it will run normal.


On a side note...why has your jeep never been over 3k rpm? Even new motors need to run the full rpm range to break in properly.
__________________
88 MJ on 40's. 98 XJ on 35's. 98 Dodge, 52psi of boost. 94 Miata LS4. 70 Buick GS455. 01 Harley, been to 46 states. 05 KTM, 576cc. 06 Husky, girls need bikes too. 2011 R6, girls need sport bikes too. 99 Toyota Avalon, daily. 97 Miata, girls apparently need miatas too.
And everything fits in the garage!
Quote:
Originally Posted by mako my day View Post
Johnx is #1
Reply With Quote
  #9  
Old August 12th, 2017, 16:37
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: Texas
Posts: 14,653
Re: Bad Transmission?

It sounds like it should be down shifting and is not. I would also suspect it is knocking, pre ignition under heavy load at too low of an rpm. I do not think a miss fire would could cause bucking (I could be wrong, I guess if the TC is locked even a miss fire might buck.)

What it sounds like for sure, is that it is not unlocking the TC and down shifting when it should to increase the torque enough.... If the TC is not locked, it should not buck even with a miss fire, (I think)

TPS????

What exactly does this mean?

" I derived the timing on that engine myself,"
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #10  
Old August 12th, 2017, 19:57
JohnX's Avatar
JohnX JohnX is offline
Sarge <3 Ben
 
Join Date: Nov 2004
Location: Rancho Cucamonga CA
Posts: 8,767
Re: Bad Transmission?

Quote:
Originally Posted by Ecomike View Post
If the TC is not locked, it should not buck even with a miss fire, (I think)
Depends a bit on the severity of the mis, but most of the time I can feel a mis regardless of gear or TC lock.
__________________
88 MJ on 40's. 98 XJ on 35's. 98 Dodge, 52psi of boost. 94 Miata LS4. 70 Buick GS455. 01 Harley, been to 46 states. 05 KTM, 576cc. 06 Husky, girls need bikes too. 2011 R6, girls need sport bikes too. 99 Toyota Avalon, daily. 97 Miata, girls apparently need miatas too.
And everything fits in the garage!
Quote:
Originally Posted by mako my day View Post
Johnx is #1
Reply With Quote
  #11  
Old August 12th, 2017, 20:04
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Re: Bad Transmission?

Quote:
Originally Posted by Ecomike View Post

What exactly does this mean?

" I derived the timing on that engine myself,"
This means that when I put the engine in it had no distributor. I put one in so I know its not off.

As to answer the questions about the sputtering and whatnot... The engine does not change in rpm level what so ever during this process. During the time that it is bucking you can only feel the vehicle bucking. No change in rpm and the engine runs smooth as can be. I would know if it ran even slightly different since it has a loud high flow exhaust.

As far as the plugs and leads go I have looked them over since this has started. All new and all good.

Im not sure if this helps but being a 98 it has the HO system. HO Jeeps tend to start within a crank or two but this one starts more like a renix Jeep. Five cranks to fire up. Already checked for fuel leaks and pump is good I know how to do all that stuff.

Engine has actually been over 3k but only maybe 10 times when emergency accel has been needed. So it has done like 95mph and once a burn out when an emergency occurred. But I dont need it to shift past 2k to accel faster than average traffic not to mention I baby it.

I am not very good with diagnosing sensors because the only one that has ever given me trouble was a cps on a friends zj so I am not sure if the tps could cause any of this or not.

Hope this is enough info, tried to break it up to make it easier. Thank you all.
Reply With Quote
  #12  
Old August 12th, 2017, 20:07
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: Texas
Posts: 14,653
Re: Bad Transmission?

Quote:
Originally Posted by JohnX View Post
Depends a bit on the severity of the mis, but most of the time I can feel a mis regardless of gear or TC lock.
If the TC is not locked, the TC fluid slippage should not allow it it to buck, at all.

There is a difference between an engine miss-shake, and an entire drive train bucking. It feels very different.

If it is in gear with a clutch engaged or the AW4 TC is locked, yes an engine miss can cause bucking.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
  #13  
Old August 12th, 2017, 20:19
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Re: Bad Transmission?

So do I need a new TC then? Or what are some options to repair this problem
Reply With Quote
  #14  
Old August 12th, 2017, 20:28
alexgalexg's Avatar
alexgalexg alexgalexg is online now
NAXJA Forum User
 
Join Date: Jan 2013
Location: Connecticut
Posts: 223
Re: Bad Transmission?

Maybe just not enough fluid getting in and I need to add more? I will see tomorrow after work. When I come home and the engine is running and hot after the commute I can check the levels. If its low I will flush the whole thing
Reply With Quote
  #15  
Old August 12th, 2017, 20:42
Ecomike's Avatar
Ecomike Ecomike is offline
NAXJA# 2091
 
Join Date: Dec 2006
Location: Texas
Posts: 14,653
Re: Bad Transmission?

I would investigate why it is not down shifting on its own, unlocking the TC, down shifting to 3rd, and then re-locking to raise the RPM due to the higher torque load going up the grade. I had that problem ages ago, but the solutions were bits and pieces of many things wrong with it (it was, is a Renix).

I had the problem with my low HP diesel (64 HP tops, LOL), 85 custom XJ, and always had to down shift to solve it climbing grades.

Have you done the Transmission cable to throttle body adjustment yet? There is an entire thread on that super simple step and how huge the effect and difference in performance is on here in this section.

Then after that, the TPS may be an issue. I drove my 87 for 13 years before I discovered this year that the throttle cable rod was bent and cheating me out of 1/3 of the beasts peak power ability at a fixed gas pedal position. I had. have 3 rigs, and when the TPS data on my scanner was wrong, I compared the throttle rods and found the 13 old issue. I thought is was worn out engine LOL, 290,000 miles.

I'd ask some of the guys with later HO rigs about the vehicle speed sensors, etc that might affect shifting, because I suspect from what your saying on going up a grade, you need to be in 2200 to 2600 rpm range or higher....in 3rd gear. Mine does 2000 rpm in 4th at 55-60 mph on flat runs.

Something in the controls is not telling it down shift I think.


Quote:
Originally Posted by alexgalexg View Post
So do I need a new TC then? Or what are some options to repair this problem
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WTB: AW4 Transmission Pan xjchris98 NAC Classifieds 0 March 3rd, 2012 19:23
Transmission leak! AM I just retarded? Transmission removal step by step tirogers Modified Tech Discussion 0 October 20th, 2009 23:17
Transmission oil pan XJ Stryker OEM Tech Discussion 6 March 16th, 2008 19:47
91 Transmission in 96 xjpio OEM Tech Discussion 3 April 29th, 2006 21:08
Transmission Day! Professor Bobo OEM Tech Discussion 3 June 21st, 2004 21:05


All times are GMT -7. The time now is 19:20.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014