Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.

engine revs on start up after changing head gasket HELP!!!!!!!

Thread Tools
 
Search this Thread
 
Old 07-11-2011 | 02:32 AM
  #1  
invictus89's Avatar
Thread Starter
Member
 
Joined: Sep 2009
Posts: 113
Likes: 0
From: louisville KY
Model: Cherokee
Default engine revs on start up after changing head gasket HELP!!!!!!!

changed my head gasket a couple days ago and after putting the engine back together, went to start it up and the engine revs to full throttle by itself. not sure why its doing it and ive triple checked everything i can think of and i cant find anything wrong or out of place. does anyone have some insight for me or some advice? anything will be helpful because im stuck.

thanks to all in advance,
brad
Old 07-11-2011 | 03:28 AM
  #2  
94JeepCherokeeMan's Avatar
CF Veteran
 
Joined: Jun 2011
Posts: 1,023
Likes: 1
From: Southern Idaho
Year: 1994
Model: Cherokee
Engine: 4.0 L/242 CID I-6 High Output MFI
Default

Massive air leak somewhere. Check all lines, seams, bolts, and retorque if necessary.
Old 07-11-2011 | 12:25 PM
  #3  
invictus89's Avatar
Thread Starter
Member
 
Joined: Sep 2009
Posts: 113
Likes: 0
From: louisville KY
Model: Cherokee
Default

ill do it today. if that doesnt work ill jumnp back on here and let everyone know. thanks a million! hope this works.
Old 07-11-2011 | 12:48 PM
  #4  
FL Denmark's Avatar
Member
 
Joined: Apr 2011
Posts: 178
Likes: 0
From: Ringsted
Year: 1997
Model: Cherokee
Engine: 4.0 L
Default

is the speeder cable correctly installed ? maybee its to tight and puls just a little on the throttle. it dont need much to rev high without load.

let us hear what you found
gohd luck
Old 07-11-2011 | 01:06 PM
  #5  
94JeepCherokeeMan's Avatar
CF Veteran
 
Joined: Jun 2011
Posts: 1,023
Likes: 1
From: Southern Idaho
Year: 1994
Model: Cherokee
Engine: 4.0 L/242 CID I-6 High Output MFI
Default

Let us know. Good luck. Good suggestion, denmark, that would easily be overlooked after doing a head gasket lol
Old 07-11-2011 | 06:11 PM
  #6  
south12xj's Avatar
Newbie
 
Joined: Jul 2011
Posts: 4
Likes: 0
From: Hampton, VA
Year: 2000
Model: Cherokee
Engine: 4.0
Default

I posted almost the same problem yesterday.Replaed the head, new gaskets, [runs fine] but revs high. I've gone through it, removed and reinstalled the manifolds(with new gasket), clamped off vac lines,retorque head bolts. I'm stumped. Could it be the IAC or TPS? Let us know if you figure it out.
Old 07-12-2011 | 08:04 PM
  #7  
invictus89's Avatar
Thread Starter
Member
 
Joined: Sep 2009
Posts: 113
Likes: 0
From: louisville KY
Model: Cherokee
Default

wnet through the whole engine and there werent any vac lines out of place or missing, and i checked the throttle cable and its actually a little loose so that couldnt be it. and its not just revving high, itll go all the way to redline. my pops in insisting that its the timing, but could i have messed that up just by changing the head gasket? and if i hear of anything else that it coud be ill be sure to let u know south12. im about to just tow it to a shop because its my dd and i cant afford to not ahave a vehicle. already lost my job over it so thats a whole new world of troubles.
Old 07-12-2011 | 08:38 PM
  #8  
SNIDELYWHIPLASH's Avatar
Member
 
Joined: Dec 2009
Posts: 207
Likes: 5
From: South Jersey
Year: 2001
Model: Cherokee (XJ)
Engine: 4.0L I6 Power Tech
Default

What was the original reason for changing the head gasket?
Did you have the head checked for cracks/warp?

A possibility:
When you put the manifolds on the head make sure you line up the 2 dowels on the intake to the head. If these don't line up the manifold is aluminum the dowel can wedge in the manifold creating a nasty vacuum leak which will cause the idle to be very high RPM (ask me how I know).
http://www.naxja.org/forum/showpost....8&postcount=12
Old 07-12-2011 | 08:38 PM
  #9  
freegdr's Avatar
CF Veteran
 
Joined: Mar 2010
Posts: 47,923
Likes: 31
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Default

bad vacuum leak under neath manifold where it bolts to head or brake booster vacuum line not hooked
Old 07-12-2011 | 09:06 PM
  #10  
sansocal's Avatar
Junior Member
 
Joined: Jun 2011
Posts: 77
Likes: 0
From: Western WA
Year: 1989
Model: Cherokee
Engine: 4.0
Default

When you leave the IAC unplugged it will rev to 2000 at least, that's when I shut it off. Check the harness to the IAC and before it. Could be something simple.
Old 07-13-2011 | 08:59 PM
  #11  
invictus89's Avatar
Thread Starter
Member
 
Joined: Sep 2009
Posts: 113
Likes: 0
From: louisville KY
Model: Cherokee
Default

all vaccuum lines are in place, the manifold is in place properly, and all plugs are plugged. im callin it quits and takin it to a shop here in town that has a nack for jeeps. ill make sure they let me know what the problem is and ill post it up on here for everyone to know. who knows, might help someone in the future.
Old 07-14-2011 | 01:19 AM
  #12  
94JeepCherokeeMan's Avatar
CF Veteran
 
Joined: Jun 2011
Posts: 1,023
Likes: 1
From: Southern Idaho
Year: 1994
Model: Cherokee
Engine: 4.0 L/242 CID I-6 High Output MFI
Default

Did you make sure everything was aligned correctly before you torqued it down?
Old 07-14-2011 | 09:34 AM
  #13  
invictus89's Avatar
Thread Starter
Member
 
Joined: Sep 2009
Posts: 113
Likes: 0
From: louisville KY
Model: Cherokee
Default

Yup. But I took it to my shop last night. Its no longer in my hands.
Old 07-14-2011 | 10:29 AM
  #14  
94JeepCherokeeMan's Avatar
CF Veteran
 
Joined: Jun 2011
Posts: 1,023
Likes: 1
From: Southern Idaho
Year: 1994
Model: Cherokee
Engine: 4.0 L/242 CID I-6 High Output MFI
Default

Good luck man
Old 07-14-2011 | 11:46 AM
  #15  
FL Denmark's Avatar
Member
 
Joined: Apr 2011
Posts: 178
Likes: 0
From: Ringsted
Year: 1997
Model: Cherokee
Engine: 4.0 L
Default

I hope its something simple, so it Will be Quick and painless.
Good luck, and remeber to let us know



All times are GMT -5. The time now is 06:07 PM.