4.0 hesitation - 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 Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > 4.0 hesitation

Trailing Arms!JK Vent Covers - NalinMFGComponent speaker deal for your dash - NalinMFG

Reply
Unread 03-14-2008, 03:50 PM   #1
underpowered
Bouncin' on a Budget
 
underpowered's Avatar
1998 ZJ 
 
Join Date: Nov 2005
Location: northern kentucky
Posts: 2,720
4.0 hesitation

my 1995 ZJ with 4.0 has a bad stumble to it. in park it revs fine, but under a load, if you tromp it, all it does is stumble and fall on its face. tried some fresh gas (who knows how old the other stuff was) with some fuel injector cleaner and it did not help. any other ideas on what i could do? probably gonna seafoam it this weekend and see what that does for it.

__________________
1998 ZJ 2" bb and 31's. street queen but sees the woods once in a while.

2000 powerjoke tow pig

Anti-jeep--1989 K5 blazer. the new off road ride
underpowered is offline   Reply With Quote Quick reply to this message
Unread 03-14-2008, 06:35 PM   #2
_Kyle_
Registered User
2008 WK 
 
Join Date: Oct 2005
Location: Abingdon, MD
Posts: 2,760
I wouldn't advise using SeaFoam since it messes with the O2 sensors in Jeeps quite often. Try Mopar Combustion Chamber Cleaner from the dealership.

Sorry that's the only advice I have though.
__________________
-Kyle

1996 Grand Cherokee

RIP Troy (bigbluezj94)

1996 ZJ FOR SALE
_Kyle_ is offline   Reply With Quote Quick reply to this message
Unread 03-14-2008, 06:38 PM   #3
Windowsrookie
Registered User
2000 WJ 
 
Join Date: Nov 2007
Location: Minnesota
Posts: 1,822
I used Seafoam just fine. My dealership charges $38 for a can of Mopar CCC.

If you're really worried about it just dump the Seafoam in your gas.
__________________
2000 Grand Cherokee Laredo 4.7L V8 Quadra-Drive
1987 Wrangler 4.2L
Windowsrookie is offline   Reply With Quote Quick reply to this message
Unread 03-14-2008, 06:38 PM   #4
Vestjam
Senior Member
 
Vestjam's Avatar
2008 JK Wrangler 
 
Join Date: Feb 2006
Location: Illinois
Posts: 763
Could be lots of things..... When was the last time the fuel filter was replaced or for that matter, the plugs, wires, cap/rotor?
Clean the throttle body also.

All things to look at...
__________________
2008 Jeep Wrangler X (Hard Top)
Incubus Off Road 511's with BFG 285/70-17

1998 Jeep Cherokee Sport
4.0L/AW4, Yakima Roof Rack
Vestjam is offline   Reply With Quote Quick reply to this message
Unread 03-14-2008, 06:57 PM   #5
_Kyle_
Registered User
2008 WK 
 
Join Date: Oct 2005
Location: Abingdon, MD
Posts: 2,760
Quote:
Originally Posted by Windowsrookie View Post
I used Seafoam just fine. My dealership charges $38 for a can of Mopar CCC.

If you're really worried about it just dump the Seafoam in your gas.
Good god, is it in a gold plated can? I paid $6 the other day, that was CHEAPER than any place had Seafoam, even on sale.
__________________
-Kyle

1996 Grand Cherokee

RIP Troy (bigbluezj94)

1996 ZJ FOR SALE
_Kyle_ is offline   Reply With Quote Quick reply to this message
Unread 03-14-2008, 09:05 PM   #6
underpowered
Bouncin' on a Budget
 
underpowered's Avatar
1998 ZJ 
 
Join Date: Nov 2005
Location: northern kentucky
Posts: 2,720
this was discussed a while back,and the thread got closed. seafoam will not hurt it. the o2 in a jeep i smade of the same stuff as an o2 on a GM,ford, or any other make. no reason it would mess up on a jeep and not on anything else.


but back on topic, no idea on when the cap/rotor/wires/plugs/filter was all changed. i just bought it 2 months ago and have not evern messed with it till this past week, when i pulled out onto the road and tromped it to do a nice 4 wheel drift into the other driveway. it spun a little bit then fell flat on its face.

i will pull the plugs and see what they look like.
__________________
1998 ZJ 2" bb and 31's. street queen but sees the woods once in a while.

2000 powerjoke tow pig

Anti-jeep--1989 K5 blazer. the new off road ride
underpowered is offline   Reply With Quote Quick reply to this message
Unread 03-15-2008, 12:05 AM   #7
my2monkeys
Registered User
1989 XJ Cherokee 
 
Join Date: Jan 2007
Location: Mission Viejo CA
Posts: 89
Did you pull the plugs yet? My wifes 95 zj 4.0 auto, is doing the same thing. Been trouble shooting it for a couple weeks. I think I narrowed it down to the fuel pump. I put a fuel press. gauge on it, routed under the hood by the windshield so I could road test and check gauge when it stumbles. Couldnt get it to stumble(figures) yesterday, it had 1/4 tank. Wife drove it today, ran good. Went to pick up kid from school and it chugs and stalls with about 2 gals in tank now. I put $20 inthe tank (now its up to 1/4 tank again), put the press. gauge back on. yesterday the gauge read 40 psi consistently, today it would drop to below 20psi when I punched it and was chugging at 20psi then go back to 40psi when I let up alittle. Think I'll pull the pump tomorrow and see if its clogging up , seems to get bad with low fuel level.
my2monkeys is offline   Reply With Quote Quick reply to this message
Unread 03-15-2008, 03:19 AM   #8
00gcl
Registered User
 
Join Date: Aug 2007
Location: NY
Posts: 12
would check the plugs and wires first... I've had the same problems in other vehicles and it was always the wires, they may look good but if they're old they're not getting the spark to the plug, especially when the rpm's go up
__________________
2000 Grand Cherokee Laredo 4.0 I6
00gcl is offline   Reply With Quote Quick reply to this message
Unread 03-15-2008, 08:52 AM   #9
underpowered
Bouncin' on a Budget
 
underpowered's Avatar
1998 ZJ 
 
Join Date: Nov 2005
Location: northern kentucky
Posts: 2,720
its goin out on the trail today for a mud fest. i will see how it acts out there. for i all know it just needs blown out as it has not been actually driven for about 6 months now.

i will probably pull the plugs and wires tonight though.
__________________
1998 ZJ 2" bb and 31's. street queen but sees the woods once in a while.

2000 powerjoke tow pig

Anti-jeep--1989 K5 blazer. the new off road ride
underpowered is offline   Reply With Quote Quick reply to this message
Unread 12-21-2011, 11:35 AM   #10
VAzj
Registered User
1998 ZJ 
 
Join Date: Dec 2011
Location: virginia beach, va
Posts: 18
I have the same problem. The idle is fine after we put the new fuel pump in. It has a slight hesitation & surges around the 1800-2500 rpm range. IAC, MAP, TPS all are brand new. Was reading about the connector to the TPS, so I get my husband to check that.

Could it be the injectors? At 150k miles... they are pretty old.

I think the CAT is bad/old & I'll have that changed too later with the 02 sensors.
VAzj 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.