Jeep Cherokee Bucking... HELP! - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > XJ Cherokee Technical Forum > Jeep Cherokee Bucking... HELP!

Huge Soft top SaleRockridge 4WD IS Taking Zone Offroad Suspension Lift Kits BLACK FRIDAY SPECIALS!! You asked, we deliver!

Reply
Unread 07-21-2008, 06:21 PM   #1
bravedeer
Registered User
1996 FSJ Cherokee 
 
Join Date: Jul 2008
Location: New Jersey
Posts: 2
Jeep Cherokee Bucking... HELP!

I had this Jeep donated to me (1996 Cherokee Sport Manual 4WD) and the previous owner said no mechanic can figure out what the problem is. Here are the symptoms:

Bucking - Car bucks/jerks. Seems worse at 1st, 2nd and 3rd gear. The car acts as if you took your foot off the gas pedal and then quickly put your foot back on it, you can hear a clunk under the car as if something is getting engaged and disengaged.

Flooring the gas pedal seems to temporarily fix it. If car is bucking and you stop, car will idle erratically, RPMs dropping down to 500 and car revs to 1500 then drops to 500 again. Car idles fine when not in bucking mode. Car seems to buck first thing in the morning. Highway driving seems to aleviate bucking.

Thanks!

bravedeer is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 06:26 PM   #2
durango-bob
Registered User
2000 TJ Wrangler 
 
Join Date: Jul 2008
Location: Sioux Falls, South Dakota
Posts: 2,928
If it were mine, I'd spend $100 at a shop that can do a proper complete diagnostic of all the sensors and systems. Then you will know what to fix. I had a similar issue with an engine miss and the computer diagnostic service pinpointed the problem after several mechanics couldn't.
durango-bob is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 07:49 PM   #3
LCFRJEEP
Registered User
1997 XJ Cherokee 
 
Join Date: Apr 2008
Location: Inwood, WV
Posts: 307
I am assuming that if you depress the clutch, the "bucking" stops??? Sounds like either a TPS mabey or something in the drivetrain is binding up. Need more info?? What all did the mechanic say and or do to your rig before you got it??
__________________
Life's too short so always do the right thing even when no one is looking and never look back!
LCFRJEEP is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 08:01 PM   #4
bravedeer
Registered User
1996 FSJ Cherokee 
 
Join Date: Jul 2008
Location: New Jersey
Posts: 2
Clutch

Yeah, if the clutch is depressed everything is fine. This happens if you are driving normally, if you floor the gas pedal there's no bucking!

I don't have enough info from the previous owner other than the fact he said the car bucks sometimes and that he brought it to several mechanics who couldn't figure it out.

I'm bringing it to my mechanic, I'm just scared that this car may become a money pit. I'll let you guys know what he thinks it is.
bravedeer is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 08:18 PM   #5
Ewen91
Registered User
2006 TJ Wrangler 
 
Join Date: Jun 2008
Location: Lunenburg
Posts: 115
my 94 jeep cherokee 4.o 5speed stick does the same thing sometimes. Mine however does not do the idle problem. I do however notice the bucking especially in 1st gear. I mean Ill let off the clutch nice and easy, and then the u go to give it some gas, and the thing is like riding a bull. Also when going down the road, in almost any gear even on level ground i will let off the gas and the jeep feels like there is so much play in the drivetrain, between leting off and geting back on, there is some kick back. The only time u dont notice it is going down hill. I have 186XXX on my jeep cherokee xj. I have about 3/4 inch or so give or take in the driveshaft when twisting it back and fourth when stopped.
Ewen91 is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 08:21 PM   #6
LCFRJEEP
Registered User
1997 XJ Cherokee 
 
Join Date: Apr 2008
Location: Inwood, WV
Posts: 307
HMMMM.... I wonder if your clutch is going out. Might be that the clutch is grabbing and engaging and then violently disengaging. Might mention that to your mechanic.
__________________
Life's too short so always do the right thing even when no one is looking and never look back!
LCFRJEEP is offline   Reply With Quote Quick reply to this message
Unread 07-21-2008, 08:47 PM   #7
Ewen91
Registered User
2006 TJ Wrangler 
 
Join Date: Jun 2008
Location: Lunenburg
Posts: 115
I plan on doing the clutch over sometime soon. I know it has a rough spot on the flywheel it seems when engaging. So new clutch and flywheel are in order. Also plan on going with new HD leafs and skyjacker nitro shocks, and coil spacer up front with new bushings all around.
Ewen91 is offline   Reply With Quote Quick reply to this message
Unread 07-23-2008, 09:44 AM   #8
RamboPants
Registered User
1987 XJ Cherokee 
 
Join Date: Jan 2007
Location: Roanoke, VA
Posts: 1,307
you would think a mech. could pin point a bad clutch though...
RamboPants is offline   Reply With Quote Quick reply to this message
Unread 07-25-2008, 04:45 PM   #9
t0ast3d
Registered User
2000 XJ Cherokee 
 
Join Date: Nov 2004
Location: Southern Ontario
Posts: 99
You might check that your idle air controller is not gummed up. Carb cleaner bath fixed that problem for me.
t0ast3d is offline   Reply With Quote Quick reply to this message
Unread 07-25-2008, 05:11 PM   #10
cmjust0
Registered User
 
Join Date: Jun 2005
Location: Central Kentucky
Posts: 65
Might check/change the fluid in the transfer case.. Mine started bucking this weekend, and I was hearing (and feeling) thumps from the undercarriage.. Didn't have any idle problems, though..

Anyway, ended up being that the transfer case was trashed.. I think the bucking and jumping was either A) teeth getting rounded off the gears, or B) broken teeth/various frag passing between the chain and the gears.. Eventually, it just started making a horrific, blood-curdling grinding noise and wouldn't go forward or backward except in 4LO..

The good news is that $356 put it back on the road with a boneyard tcase, and that included parts and labor at a mechanic's shop.
cmjust0 is offline   Reply With Quote Quick reply to this message
Unread 07-25-2008, 11:36 PM   #11
chocflip201
Registered User
1988 YJ Wrangler 
 
Join Date: Mar 2007
Location: Utah
Posts: 668
I used to have a manual Jetta before my xj and it had this same problem. im not entirely sure about the manual xj since how mine and all the ones i know personally are auto. but it turns out there is a sensor called a WOT switch (wide open throttle) on my jetta that would change that air-fuel ratio when the throttle is fully depressed to avoid blowing up the engine. fixed the switch and TA DA the erratic idle was fixed and it drove like new again. hope this can help in some way.
chocflip201 is offline   Reply With Quote Quick reply to this message
Unread 07-25-2008, 11:42 PM   #12
chocflip201
Registered User
1988 YJ Wrangler 
 
Join Date: Mar 2007
Location: Utah
Posts: 668
p.s. it just seems to me like the description of your problem seems more like a "proper engine running" problem more than a worn out clutch/transfercase etc whereas you havnt described any wierd/loud/scary noises or hard shifting or clutch slipping symptoms.
chocflip201 is offline   Reply With Quote Quick reply to this message
Unread 09-11-2008, 08:03 PM   #13
94gc4.0
Registered User
 
Join Date: Nov 2006
Location: staten island ny
Posts: 11
just stoped my bucking

my 87 cherokee was doing the same thing had a bad idle air control clean it up but still would not move
94gc4.0 is offline   Reply With Quote Quick reply to this message
Unread 09-11-2008, 08:59 PM   #14
yagelanthony
Registered User
1990 XJ Cherokee 
 
Join Date: Sep 2008
Location: Florida
Posts: 28
I have a 90 xj sport and it just started doing it the other day and it sucks the fuel down. Im talkin about 70 miles so far on a half tank!!!!
yagelanthony is offline   Reply With Quote Quick reply to this message
Unread 09-12-2008, 01:01 AM   #15
BrunoS
Registered User
 
Join Date: Aug 2004
Location: South Bay Los Angeles, CA
Posts: 2,534
interesting.

having the same exact xj, heres my two cents:

1) the 96, 5-spd manual 4x4 is probably tops among xj's to own.

2) bucking like you describe could be few things. try in this order:

replace fuel filter. its a $12 part and 10 minutes of work. you need good fuel volume and pressure for good idle and driveability.

there's a fair chance the tps has a worn out spot in it. how to check very easily: get the motor warmed up and disconnect the TPS connector. the check engine light will come on, but should drive fine. if bucking stops, TPS is worn out and is a normal replacement item around 100-140k miles or so. reconnect it when done.

if it's not the tps....the next up is the idle air motor. this is the most likely suspect with the crazy idle where the idle air motor picksup some engine load when you first let out the clutch in 1st gear. use a torx 15 and remove it, clean all the gunk off it, and re-install. then, if it still bucks, get a decent idle rpm and disconnect the IAC (idle air control motor). drive around . if bucking stops now...then you still have bad carbon residue or a worn out IAC .

look, it should be an easy fix, and you do have a rare, great 4.0 xj. with a high flow muffler/cat/ MSD blaster coil/K&N air filter, some overdue fluid changes/plugs/wire cap rotor...you will have an awesome daily ride. it won't cost much, and is incredibly tough.

odds are also very good that the original fan clutch is worn out ($40) normal wear item as well, and is #1 reason for running too hot above 210'F.

here's the biggest tip of all: stickshift 4.0's are known to shear off the motor mount bolts going in to the engine block on the right side, below the ignition coil....if they are loose, replace them/check them!!! these would be the plate that goes against the block, on each side, just above the oil pan. I sheared all 3 a month ago and only wish someone told me the same to check them, there are postings of 95+ year models (only with stick, around 5% of 4.0's have stick!!) that the bolts vibrate loose and shear off due to the high torque output of these motors. if you feel a lot of vibration in the stick (left to right) while going uphill in 1st gear or 5th down the freeway...YOUR BOLTS are loose, trust me... there's a huge difference in smoothness when the bolts are correct, and much smoother idle/freeway feel.

have fun.
__________________
Newly Painted! Emerald Green '96 XJ 4x4 4.0 HO 5-spd
3" Lift + 31" Tires / D35 TracLok / NP231
Drilled out Stock Airbox / Gauge Cluster Upgrade
Magnaflow Muffler / High-flo Cat / MSD Coil
BrunoS is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com 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 e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
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


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.