Bad tranny or cat. converter ? - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-24-2012, 07:15 AM   #1
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
Bad tranny or cat. converter ?

Hello all,

A month a go i was offered an '96. YJ 4.0 with auto transmission. I test driven it and it was accelerating like a turtle, only rev up to some 2000 and then shift up. I floored it all the time but it wouldnt go past 50-55mph. Could this be tranny or cat conv failure? Or maybe engine, but i heard those 4.0 are bullet-proof.

Regards,
Petar

zidodcigalah is offline   Quote Quick Reply
Old 06-24-2012, 07:30 AM   #2
Jeeper
 
stykthyn's Avatar
 
Join Date: Mar 2011
Location: gainesville florida
Posts: 1,168
Sounds like cat to me. Most likely it got wet and is plugged now.

__________________
1995 YJ- daily driver
1987 Mustang- the money pit. " I wanna go fast!"
stykthyn is offline   Quote Quick Reply
Old 06-24-2012, 11:51 AM   #3
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Honestly, it could be any number of things, but I would check all the easiest things first.

Is the check engine light on? If so, pull the codes...

If not, start checking things... does it run smooth otherwise? How many miles?

It could be, and more than likely is the cat over the transmission, but you cannot discount an actual engine issue.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 06-24-2012, 01:12 PM   #4
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
The engine light wasn't turned on.. But i pulled out the codes and as far as I remember it was something about oxygen sensor. There was some other code but I dont remember about what.. Unfortunatly i can't contact seller before sunday to check it again.

It runs smooth,starts at once, revs are constant on idle etc.. Also it shifts correctly, but shifts to soon(on some 2000rpm) and it takes time to get to 2000rpm. Everything seems fine about engine except acceleration. Kick-down or flooring it doesn't have any effect, it still moves like an old rag..Like it has 18 hp instead of 180...I had trouble hitting 50mph.. And it seems like it can't go any faster..

Odometer reads some 105 000 miles...A bit bigger tires than stock, some 30s are on it on stock gearing.. So I guess that can't be the problem

My first toughts were about tranny... But I've read some articles about connection between clogged cat and auto transmission,and it says that because of wrong readings computer doesnt give engine fine mixture of O2 and fuel and causes loss of power and auto tranny to shift sooner so it wont damage engine, or something like that...
zidodcigalah is offline   Quote Quick Reply
Old 06-24-2012, 02:16 PM   #5
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
That helps, Im leaning towards a clogged cat. Especially since it can be easy and cheap to verify. If it ends up not being the problem youre not out too much.

To check, I would recommend completely removing the cat and either run it with it open, or put in a temp pipe. Really the only difference would be the noise, and see if the power picks up and it runs pretty good. It may be a bit unnerving to run it with it open like that, but if you can ignore the noise and the change in performance, you can tell if the power has come back. I like putting in a pipe so the cops are not alerted, and I can get it out and run it good to see if things seem normal.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 06-24-2012, 10:42 PM   #6
Jeeper
 
Join Date: Mar 2012
Posts: 47
ha just hap to me cog cat only go 50 m.p.h but now it go 75 m.p.h put hole in cat ha ha
pupa1 is offline   Quote Quick Reply
Old 06-29-2012, 11:21 AM   #7
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
thanks people i'll check it in a next couple of days
zidodcigalah is offline   Quote Quick Reply
Old 06-29-2012, 11:39 AM   #8
The Rogue Moderator

::WF Moderator::
 
Cons_Table's Avatar
 
Join Date: Aug 2009
Location: Ridgecrest, CA
Posts: 7,572
I have never tried this so I cant verify it, but I have heard that sometimes if your cat is bad...after u drive it for a while, turn it off, go and listen to the cat, and if the cat is popping like popcorn it's bad.

I had a bad cat on my previous car (not on my jeep) and it had no pickup and lugged bad.
__________________
Poor Boy Racing The definition of the EVERYMAN Challenge!

Everyman Challenge XJ Build
Cons_Table is offline   Quote Quick Reply
Old 06-29-2012, 12:51 PM   #9
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Quote:
Originally Posted by Cons_Table View Post
I have never tried this so I cant verify it, but I have heard that sometimes if your cat is bad...after u drive it for a while, turn it off, go and listen to the cat, and if the cat is popping like popcorn it's bad.

I had a bad cat on my previous car (not on my jeep) and it had no pickup and lugged bad.
that is not necessarily true; your entire engine/exhaust system will pop and ping as it cools down, its the nature of heat expansion and cooling contraction.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 06-29-2012, 01:05 PM   #10
The Rogue Moderator

::WF Moderator::
 
Cons_Table's Avatar
 
Join Date: Aug 2009
Location: Ridgecrest, CA
Posts: 7,572
Quote:
Originally Posted by camarozz View Post
that is not necessarily true; your entire engine/exhaust system will pop and ping as it cools down, its the nature of heat expansion and cooling contraction.
The impression I got was an excessive popping like popcorn, not the typical pop and ping from cooling. This is just all hear-say...it may be possible that this has to be done while it is running not sitting. I honestly can't remember for sure.
__________________
Poor Boy Racing The definition of the EVERYMAN Challenge!

Everyman Challenge XJ Build
Cons_Table is offline   Quote Quick Reply
Old 06-29-2012, 01:20 PM   #11
Founder, ThumbJeeps

WF Supporting Member
 
sevenservices's Avatar
 
Join Date: Sep 2009
Location: Mid-Michigan/Thumb
Posts: 3,952
no one mentioned brakes yet... I've seen that to. Spin each wheel up off the ground and be sure they're not dragging anywhere.

You can also put in N without it running, on flat ground and you should be able to push the jeep forward a foot or so by yourself with minimul effort. Make sure you can roll it easy. If you can roll it easy with no drag, the problem is NOT in your axles, brakes or trans.

Aside from that, check the cat for air flow but also check your air filter box. I've seen leaves get carried into an air box and it makes it run like it is choked all the time and is super sluggish plus can only do 40-50mph struggling. Oh, distributer cap and rotor can cause it as well. If you hadn't changed 'em yet, its cheap and they are designed to fail so its worth a shot.
__________________
-Chris
Founder, ThumbJeeps


1994 Wrangler YJ I6 4.0 H/O Auto 3 spd. 4" RC (33x12.5) (15x8) 3:54 Gears
sevenservices is offline   Quote Quick Reply
Old 06-29-2012, 01:46 PM   #12
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Quote:
Originally Posted by sevenservices View Post
no one mentioned brakes yet... I've seen that to. Spin each wheel up off the ground and be sure they're not dragging anywhere.

You can also put in N without it running, on flat ground and you should be able to push the jeep forward a foot or so by yourself with minimul effort. Make sure you can roll it easy. If you can roll it easy with no drag, the problem is NOT in your axles, brakes or trans.

Aside from that, check the cat for air flow but also check your air filter box. I've seen leaves get carried into an air box and it makes it run like it is choked all the time and is super sluggish plus can only do 40-50mph struggling. Oh, distributer cap and rotor can cause it as well. If you hadn't changed 'em yet, its cheap and they are designed to fail so its worth a shot.
You know, I was thinking something very similar last night. Get the jeep up on stands and spin the tires looking at the drivelines, and get a feel for where the binding or drag problem is. If its driveline, say bad angle, you will see it be the problem when you spin the tires.

Still could be in the tranny/tc though, but I would think it would be a constant issue and not one so fleeting.

Trouble being, its very difficult to troubleshoot without being able to drive and check in person. Sometimes those little nuances that occur with the problem give it away, and without being able to see/hear/feel them it is just a good hearted guess at this point.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 06-29-2012, 01:49 PM   #13
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Quote:
Originally Posted by Cons_Table View Post
The impression I got was an excessive popping like popcorn, not the typical pop and ping from cooling. This is just all hear-say...it may be possible that this has to be done while it is running not sitting. I honestly can't remember for sure.
Ah gotcha; and I suppose it may be one way to check, but honestly with my bad cats I have never heard anything out of the ordinary, it was just a "guess" based on a friends advice and it happened to be the problem.

The one I had taken 3 of the four bolts off, then the fourth got stuck about half way and it was still a problem. Cut that sucker off and the car ran like a raped ape.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 07-04-2012, 11:50 AM   #14
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
cat removed, but again same thing... like its lagging... checked engine compression readings are 120+-5 psi.. it throws code 21 for 0o2 sensor... could it be tge problem.. or ail filter?
zidodcigalah is offline   Quote Quick Reply
Old 07-04-2012, 12:28 PM   #15
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
ooo, that changes things.

My opinion, O2 wont cause that problem; but a very clogged Air filter could. You could remove it and see how it runs, but I would think it would take a VERY clogged filter for it to do that.

It does sound like it could be tranny, check the fluid even change it (and filter if possible) Check your vacuum lines, especially the one to the transmission, and if you even know a trans guy see if he can give you an opinion.

What does it rev to as it starts to move?
Can you do a power brake, hold the brakes and rev the motor and see where it stalls. Typically at some point the revs will not go any higher no matter how much throttle is applied, that is the number needed.
Have you checked at the trans for unconnected connectors/hoses/ oddities?

Im trying to find what transmission you have, but I cannot locate it; are you sure its a '96? or could it be a '97? Is it a 3 speed or 4 speed auto? Or do you know what trans you have?
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 07-04-2012, 02:23 PM   #16
Jeeper
 
Redrider94's Avatar
 
Join Date: Aug 2010
Posts: 651
It would have to be either a 95yj or a 97 TJ no wranglers were built with a 96 year, anything early 95 was sold as a 95. Does your jeep have round or square headlights? Round = 97 or after, square = 95 or earlier.
Redrider94 is offline   Quote Quick Reply
Old 07-04-2012, 02:24 PM   #17
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
auto, 3 speed no overdrive.. same as in 95. models... engine seems to be ok.. i feel like it has lack of power...
zidodcigalah is offline   Quote Quick Reply
Old 07-04-2012, 02:25 PM   #18
Jeeper
 
Redrider94's Avatar
 
Join Date: Aug 2010
Posts: 651
Quote:
Originally Posted by Redrider94
It would have to be either a 95yj or a 97 TJ no wranglers were built with a 96 year, anything early 95 was sold as a 95. Does your jeep have round or square headlights? Round = 97 or after, square = 95 or earlier.
Sorry meant to say ( anything early 96 was sold as a 95)
Redrider94 is offline   Quote Quick Reply
Old 07-04-2012, 02:49 PM   #19
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Than it looks like a TF999 trans, Jeep Wrangler - Wikipedia, the free encyclopedia

If that is any help...

You can try to change the O2, cant hurt. But it seems a bit odd for it to be causing such an issue.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 07-05-2012, 03:54 PM   #20
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
Yeah its a tf999.. anyway, what are symptoms of a bad 02?
zidodcigalah is offline   Quote Quick Reply
Old 07-06-2012, 12:23 AM   #21
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
Typically, running rough, bad gas mileage, and a check engine light.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 07-06-2012, 08:59 AM   #22
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
Well, seems like tranny is a problem.. Because engine behaves normal on idle, just a little pressure on throttle pedal and revs go wild When it moves, seems like its dying to get to 3000rpm.. Might be torque converter, or something in tranny..
Anyway thank you all for your tips and answers And just another one question..
Since Wranglers are rare in my country, i cant find parts for them on junkjards. I was thinking about converting it from automatic to manual, but I cant find an AX-15 transmission from wrangler, only from old Cherokees with same 4 litre engine.Would that one form cherokee fit inside wrangler,and Are there any major modifications needed since its the same transmission, but from different car?
zidodcigalah is offline   Quote Quick Reply
Old 07-06-2012, 09:10 AM   #23
Jeeper
 
Join Date: Jun 2012
Location: Central Washington
Posts: 1,207
For the most part it should fit, depending.

You will need the pedals, the hydraulics (master/slave and lines), the flywheel, all the linkages, the bell housing and possibly the transfer case. (someone else may be able to verify that). Once you get all that it should be fairly easy.

If you get the TC with the set, you would need to re-clock the TC to the transmission. It typically is shifted lower on a cherokee, and to clear your skid plate it would need to be redrilled and shifted. Not a big deal, there is plenty of room to drill new mounting holes.

If you dont, be sure to check the output spline count on the trans to match the input spline count on the TC or you will need to replace that input shaft on the TC.
__________________
Gotta stand by all you cool guys... Maybe it'll rub off?!
camarozz is offline   Quote Quick Reply
Old 07-06-2012, 01:22 PM   #24
Jeeper
 
zidodcigalah's Avatar
 
Join Date: Jun 2012
Posts: 75
Seems that both tf999 and ax15 have 23 spline output. so i guess i wouldnt need TC also, seems that the driveshafts arent compatible so i'd have to change them too

zidodcigalah is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 03:59 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC