TJ running wide open. Need help! - Pirate4x4.Com : 4x4 and Off-Road Forum
 
Pirate4x4.Com : 4x4 and Off-Road Forum  

Go Back   Pirate4x4.Com : 4x4 and Off-Road Forum > Brand Specific Tech > Jeep - Hardcore Tech
Notices

Reply
 
Share Thread Tools Display Modes
Old 11-05-2004, 06:52 PM   #1 (permalink)
Registered User
 
NATO4x4's Avatar
 
Join Date: Oct 2003
Member # 23862
Location: McClellanville,South Carolina
Posts: 41
TJ running wide open. Need help!

I was just helping some guys put a header on a TJ with a 4.0. Got it bolted up and when we cranked it it ran wide open hitting the rev limiter for a few seconds. Disconnected the neg cable and checked all connections and still when we crank it the thing runs wide open. The butterfly on the TB is not even opening. What would make it pump that much fuel? Could the air flow sensor be wacked out?
__________________
1980 Toyota pickup, 22rec, 36" IROKS, rears and chevys, 4.38s welded R,Aussi F, DOM cage.
2006 Chevy 2500HD D/A
1986 Isuzu Trooper II Headache.
1997 Grand Cherokee 2wd grocery getter.
NATO4x4 is offline   Reply With Quote
Old 11-05-2004, 07:38 PM   #2 (permalink)
Mo
Everyday is Tuesday.
 
Mo's Avatar
 
Join Date: Feb 2000
Member # 47
Location: Lizzy, CO
Posts: 15,752
stuck throttle cable?
Mo is offline   Reply With Quote
Sponsored Links
Old 11-05-2004, 07:47 PM   #3 (permalink)
Registered User
 
Join Date: Apr 2004
Member # 29856
Location: SFV, CA.
Posts: 89
Vaccum leak. Check around the intake and exhasut manifolds for leaks.
__________________
95 YJ 4.0L Auto. VIRTUAL HAMMERS RALLY POST #53
YJ_WOLF95 is offline   Reply With Quote
Old 11-05-2004, 08:50 PM   #4 (permalink)
Wheeler
 
lankchevy's Avatar
 
Join Date: Sep 2003
Member # 22909
Location: soutwest missouri
Posts: 178
Send a message via Yahoo to lankchevy
sounds like what my xj 4.0 did when the IAC sensor went out, basicaly just a solinoid that lets the motor have some extra air when its cold or on start up, i didnt have any money at the time and so i built a block off plate and havent had a problem since. ya its red neck fab at its worst but it gets the job done, it was free, and the only downside is u have to crank it for 2-3 seconds before itll start. but i hated how before when u started it flew up to 2k then slowly went back down. now it starts and doesnt jump way up. every been driving an auto and had the iac stick open? not alot of fun. mine went out at a drive thru dairy queen.

kolby
__________________
88 xj 4.0 aw4 np231
36s hp44 - 8.8 5.13s
chopped and caged
109"wb
lankchevy is offline   Reply With Quote
Old 11-05-2004, 10:21 PM   #5 (permalink)
Registered User
 
Join Date: Oct 2004
Member # 37430
Location: Jackson and Starkville, MS
Posts: 288
when you bolt the intake manifold back on you have to hold it up while snugging up the first few bots or it will slide downwards and let air leak in the intake ports. I had the same problem on mine...
MudTJ is offline   Reply With Quote
Old 11-05-2004, 11:52 PM   #6 (permalink)
Registered User
 
NATO4x4's Avatar
 
Join Date: Oct 2003
Member # 23862
Location: McClellanville,South Carolina
Posts: 41
What is funny is that the throttle is not opening at all. We looked down the TB and it does not open. It is back firing so that means its not getting enough air to burn the fuel. For whatever reason the injectors are pumping wide open as soon as it cranks. I think if we let it run it would bounce off the rev limiter until it blew up. Ill check vac hoses, and intake position tomorrow.
__________________
1980 Toyota pickup, 22rec, 36" IROKS, rears and chevys, 4.38s welded R,Aussi F, DOM cage.
2006 Chevy 2500HD D/A
1986 Isuzu Trooper II Headache.
1997 Grand Cherokee 2wd grocery getter.
NATO4x4 is offline   Reply With Quote
Old 11-06-2004, 12:59 AM   #7 (permalink)
Registered User
 
Join Date: Jun 2003
Member # 20592
Location: Mobile, AL
Posts: 1,258
Send a message via AIM to gumbojeepyj Send a message via Yahoo to gumbojeepyj
iac motor or severe intake vacuum leak, that's all it could possibly be.
__________________
Blake
http://www.lockitupoffroad.net
gumbojeepyj is offline   Reply With Quote
Old 11-06-2004, 01:44 PM   #8 (permalink)
Registered User
 
Join Date: Oct 2004
Member # 37559
Location: Kansas City
Posts: 16
I agree the Idle Air control is most likely stuck open
YHIKE is offline   Reply With Quote
Old 11-06-2004, 03:12 PM   #9 (permalink)
Registered User
 
Join Date: Jan 2003
Member # 16217
Location: Houston, Texas
Posts: 228
Send a message via ICQ to JeremyH Send a message via AIM to JeremyH
Quote:
Originally Posted by YHIKE
I agree the Idle Air control is most likely stuck open
They get gummed up, but it is unlikely that symptoms would only arive after the install.
JeremyH is offline   Reply With Quote
Old 11-06-2004, 03:15 PM   #10 (permalink)
Granite Guru
 
87yj38's Avatar
 
Join Date: Sep 2002
Member # 14010
Location: Asheville, NC
Posts: 671
Send a message via AIM to 87yj38
Most likely did not engage the intake manifold on its dowel pins on the block, look up from underneath and check. Huge vaccumn leak...

I'll bet thats it.
__________________
www.ujointoffroad.com
87yj38 is offline   Reply With Quote
Old 11-06-2004, 06:40 PM   #11 (permalink)
Registered User
 
jeeplord's Avatar
 
Join Date: Mar 2004
Member # 28273
Location: East of the Rockies
Posts: 513
Quote:
Originally Posted by YHIKE
I agree the Idle Air control is most likely stuck open
Newb response. You changed the exhuast manifold and didn't get it to seat properly. Did you check to make sure the flange was clean and didn't have any burrs? The smallest piece of junk will hold the header out and allow excessive air into the mix.

The Jeep is running was lean and it drives the RPMs up. If you let it go a minute you'll be able to see just how red a header can get, you'll almost be able to see though it (don't really try it, not worth the other damage you might do.

Take the whole thing apart, get another gasket and make sure that flange is clean. I know it takes 2 hours to take it all apart, but the current shop charge for that job is 7 hours total!

It has absolutely nothing to do with your IAC, so save yourself the trouble and fix the real problem.
__________________
[QUOTE=kodiak1232003]"RUN, WHITE PEOPLE!! RUN!..SAVE YOUR FAWKING SELVES!!!" or some sh#t, in broken engrish...."[/QUOTE]
jeeplord is offline   Reply With Quote
Old 11-07-2004, 08:42 AM   #12 (permalink)
Registered User
 
Join Date: Sep 2000
Member # 1699
Location: Wichita Falls, TX
Posts: 23
Quote:
Originally Posted by jeeplord
You changed the exhuast manifold and didn't get it to seat properly. Take the whole thing apart, get another gasket and make sure that flange is clean.

It has absolutely nothing to do with your IAC, so save yourself the trouble and fix the real problem.
This is exactly correct. I have worked on these engines many times and this is a common mistake. I have made it myself in the past. If you examine it closely you will find where the intake/exhaust manifold is not seating correctly. This lets a lot of air get into the engine just like an open throttle body would. USE A NEW GASKET! Some people try to reuse the old one and eventually it will do nothing but cause you to have to do this all over again.
__________________
Have a rock and a smile!
CreatureXJ is offline   Reply With Quote
Old 11-07-2004, 08:58 AM   #13 (permalink)
Registered User
 
sothpaw's Avatar
 
Join Date: Jan 2002
Member # 9279
Location: over there
Posts: 262
Send a message via AIM to sothpaw
Quote:
Originally Posted by YJ_WOLF95
Vaccum leak. Check around the intake and exhasut manifolds for leaks.
x2. I had a small leak on mine and it would idle around 2k.
__________________
______
SI VIS PACEM PARABELLUM

FJ40john: WTF are you talking about man?? You need a disclaimer at the top of this that says "If you are a pale friendless virgin (male or female), who likes (insert whatever the hell you were rambling about here), please read on...everyone else, please disregard."
sothpaw is offline   Reply With Quote
Old 11-08-2004, 08:15 AM   #14 (permalink)
Registered User
 
Join Date: Nov 2002
Member # 14952
Location: Des Moines, IA
Posts: 73
Check your gasket- if your header came with two (the Borla's used to) the gaskets are probably different- if you use the wrong one, you will have a massive vacuum leak that causes the high idle. I thought the two gaskets were identical when I put a borla header on a 4.0, but two of the intake ports on one of the gaskets were larger on one of them, which caused the massive vacuum leak.

Sorry to tell you, you had better tear it all back down and start over.
__________________
87 YJ: 5.3 Vortec, D44/ARB, D60 Detroit, 5.13s,38.5 SXs, 44044s SOA

Last edited by VortecYJ; 11-08-2004 at 08:16 AM.
VortecYJ is offline   Reply With Quote
Reply

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
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 06:25 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 ©2011, Crawlability, Inc.