99 Tj stalls at stop and no guts when engine is cold - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 04-28-2011, 02:11 PM   #1
Newb
 
Join Date: Apr 2011
Posts: 4
99 Tj stalls at stop and no guts when engine is cold

Hey guys i need some help. I have a 99 TJ 4.0 I6 auto trans with about 50,000 miles on it. And for about a month now when i start the engine in the morning and start driving it seems like the engine is lagging and the jeep doesnt really have any guts. i push the gas pedal and it doesnt increase speed. But if I just floor it, itll take off. And when i come to the stop sign at the top of my street then engine rpms drop real low and it kinda goes up and down and sometimes it will stall. It only does this when i first start the engine when the engine is cold. once the engine warms up everything is fine. well last night i left a friends house to head home and i got to the bottom of his street and the engine stalled. but this time I had a hard time starting it, this was the first time it was hard to start. I turned the key and it just cranked for like 10 seconds and didnt start. I let it sit for a few seconds and tried again. after about 10 seconds of cranking it started. I've looked on a ton of jeep forums and people have similar problems and nobody ever seems to get an answer to this problem. Anyone having this same problem? any suggestions? I though maybe I had a dirty IAC because of all the stuff I read on forums but since last night I had a hard tome starting it I thought it could be the fuel pump going bad? Any help is much appreciated. Thanks!

jstuebs is offline   Quote Quick Reply
Old 09-08-2011, 09:47 PM   #2
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
Have you found out what the issue was, I am having the same exact issues right now

Does anybody out there have an idea???

Thanks

RockHound is offline   Quote Quick Reply
Old 09-08-2011, 10:04 PM   #3
moe
Jeeper
 
moe's Avatar
 
Join Date: Sep 2010
Location: Marseilles,Il
Posts: 150
Try cleaning the carbon off of and out of your Idle Air Controll valve, its on the backside of the throttle body..
__________________
If the wife knew how much I got in this thing I'd have to sleep in it!!
moe is offline   Quote Quick Reply
Old 09-09-2011, 09:37 AM   #4
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
Will do that this morning thanks
RockHound is offline   Quote Quick Reply
Old 09-11-2011, 11:07 AM   #5
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
There was a lot of carbon build up, cleaned it thoroughly and the problem still exist. Yesturday at idle started running like missing and stalled. Would not start back up. Eventually it would start but would still act like it was missing, backfiring through the intake. If you let is set for about an hour now runs like a champ. Have no idea, thinking about the idle control valve. My buddy said that controls air and fuel mixture, thinking maybe that is acting up confusing the computer on fuel delivery???
RockHound is offline   Quote Quick Reply
Old 09-11-2011, 11:19 AM   #6
Jeeper
 
farlok72's Avatar
 
Join Date: Jun 2010
Location: SD, CA
Posts: 20
I have the same jeep but with 115k and had similar problems. I changed the plugs, wires, cap and rotor and it's all better. But just yesterday my jeep had no power at the end of a steep highway grade. I have heard that a bad cat can really affect a vehicles performance also. Best of luck.
farlok72 is offline   Quote Quick Reply
Old 09-11-2011, 04:52 PM   #7
moe
Jeeper
 
moe's Avatar
 
Join Date: Sep 2010
Location: Marseilles,Il
Posts: 150
Oxygen sensor senses the air/fuel ratio and adjusts injector pulse width vs how much air is going thru intake.... If now ur havin a drivability problem i would have like autobone plug into ur vehicle.... Look for oxygen sensor codes..... Just went thru a deal with mine and it ended up bein a lazy (bad at times) pre convrter o2 sensor that caused lean missfires... ????
__________________
If the wife knew how much I got in this thing I'd have to sleep in it!!
moe is offline   Quote Quick Reply
Old 09-11-2011, 05:03 PM   #8
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 31,208
Images: 2
Quote:
Originally Posted by RockHound View Post
There was a lot of carbon build up, cleaned it thoroughly and the problem still exist. Yesturday at idle started running like missing and stalled. Would not start back up. Eventually it would start but would still act like it was missing, backfiring through the intake. If you let is set for about an hour now runs like a champ. Have no idea, thinking about the idle control valve. My buddy said that controls air and fuel mixture, thinking maybe that is acting up confusing the computer on fuel delivery???
Did you not separately specifically clean the gunk off the Idle Air Controller as suggested above? Only two screws hold it to the throttle body so it's easily removed and cleaned with a toothbrush and aerosol throttle body cleaner. Use something to clean out the hole in the throttle body the IAC's plunger fits into too, like a baby bottle nipple brush.

The IAC only feeds air into the engine at idle when you are not stepping on the gas pedal, it doesn't have anything to do with the air/fuel mixture.

If your mpg took a sudden recent nosedive and you can smell fuel, perhaps your upstream 02 sensor has gone bad.
__________________
When you have a choice, buy American.

Jerry Bransford is offline   Quote Quick Reply
Old 09-11-2011, 07:23 PM   #9
Jeeper
 
tella's Avatar
 
Join Date: Aug 2010
Location: Jackson, WY.
Posts: 65
Mine just started today.
tella is offline   Quote Quick Reply
Old 09-11-2011, 07:56 PM   #10
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
I removed the IAC and cleaned it with throttle body cleaner, along with the hole in the throttle body itself. I have never smelled fuel and have not noticed the milage decreasing. But i do know the o2 censors have not been changed and there is about 135K on the jeep
RockHound is offline   Quote Quick Reply
Old 09-11-2011, 08:19 PM   #11
Knows a couple things...

WF Supporting Member
 
Jerry Bransford's Avatar
 
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 31,208
Images: 2
The Throttle Position Sensor can get dirty inside and cause all kinds of intermittent idle and acceleration problems. The bad news is that it is not cleanable like the IAC is, it needs to be replaced when it goes bad. The TPS is the sensor that tells the engine computer what position the throttle (via your foot on the gas pedal) is at.

I would try one thing to see if the symptoms change any which if they do, would indicate the TPS is probably bad. Work the throttle linkage or the accelerator pedal fully 50-100 times. That will cause the wiper inside that makes a variable resistance connection to wipe back & forth on its resistor and possibly clean up the connection or knock loose carbon off to the side where it temporarily won't cause any problems. If it starts running better afterwards, that's pretty conclusive evidence of a bad TPS.

If it doesn't help, that doesn't necessarily mean the TPS is good... just that it may be beyond the temporary help of cycling it 50-100 times.
__________________
When you have a choice, buy American.

Jerry Bransford is offline   Quote Quick Reply
Old 09-19-2011, 08:30 AM   #12
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
So far I have:

Changed MAP Sensor
Changed Crank Sensor
Cleaned TPS and Throttle Body

Still will run great, then suddenly start miss fireing at lower RPM's. When at a stand still It will try to stall, I will keep pumping the gas pedle and it is like no fuel is delivering. Will backfire through the exhaust and intake.

Plan on replacing O2 sensors tonight, i will let you all know what happens......
RockHound is offline   Quote Quick Reply
Old 09-19-2011, 07:43 PM   #13
moe
Jeeper
 
moe's Avatar
 
Join Date: Sep 2010
Location: Marseilles,Il
Posts: 150
Wut did u come up with Rock?
__________________
If the wife knew how much I got in this thing I'd have to sleep in it!!
moe is offline   Quote Quick Reply
Old 09-19-2011, 07:56 PM   #14
Jeeper
 
mudslinger5000's Avatar
 
Join Date: Mar 2010
Location: Lenoir, NC
Posts: 258
i have the same problem. i have an auto trans and when i back out of the driveway i usually put it in neutral and let it roll a little then put it in drive and most of the time it stalls. then when i crank it back up it'll run rough for like 30 secs or until i rev it up a little. but it doesnt do it hardly at all in the summer. someone said it might be the crank position sensor?
__________________
'99 wrangler TJ 4" RC lift, 33x12.50 BFG KM2's, Banks Monster Catback, Warn M8000
'07 JK 4-door Rescue Green 3" RC lift, 33x11.50 Nitto terra grappler (dad's)
mudslinger5000 is offline   Quote Quick Reply
Old 09-21-2011, 10:29 AM   #15
Jeeper
 
RockHound's Avatar
 
Join Date: Sep 2011
Location: Ogden Utah(4.5 hours from Moab)
Posts: 92
Last night i drove around town hoping to get the jeep to do its thing. I parked it at my buddies place and left it running in the drive way. Well after about 15 minutes it started to die out. This time it would not start, again I checked the fuel pressure by pushing in the valve with a scredriver. I have done this in the past and it would allways spray out, thinking it was good. Well the gas did not spray out, just ran out slowly. So i started thinking fuel pump again, checked power going back to the pump and good to go. But the pump would not run all the time when turning the key on. So i replaced it last night and so far running like a dream. I was thinking back and all the times it would die i would have 1/4 tank or a little more of gas. Thinking the fuel pump was getting hot and stop running. I am not one of those guys who keeps the tank full all the time. My neighbor works for an auto store and said in the past couple years with fuel cost they have sold alot of fuel pumps becouse people do not keep there tanks full, and gas is what cools the pump. So hopefully I have finally figured it outNot sure how much a fuel pressure gage cost, but I may have been able to figure this out a while ago if I had one. Just becouse gas sprays out does not mean it is good presure to run.....

RockHound 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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Please Help! 2005 Jeep Wrangler Engine Suddenly Stops While Driving mariah9999 TJ Tech Forum 31 04-16-2014 07:14 AM
Engine stop nleal61122 New York Jeep Forum 0 03-13-2011 08:33 AM
1989 6 cyl stalls at stop sign and when clutch is engaged while slowing down ducatiman YJ Tech Forum 12 07-16-2010 03:56 PM
Jeep Stalls In Cold Weather for Newbie DBRASS3497 TJ Tech Forum 4 12-21-2008 09:35 PM
my tj engine just stop to work marko_tj TJ Tech Forum 3 06-05-2006 11:32 AM



» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 04:03 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