Engine REVs high at start after manifold replacement :confused: - JeepForum.com
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 Wrangler Forums > TJ Wrangler Technical Forum > Engine REVs high at start after manifold replacement :confused:

FS: Wranger BRIGHT License Plate LED! Just $3! Great valueFS: Jeep Fog Light LED Bulbs! Several Brightness Options! Model 54 Rotary Bender - 90 degree 1 shot with auto stop f

Unread 01-09-2011, 09:06 PM   #1
Registered User
1997 TJ Wrangler 
Join Date: Feb 2006
Location: Southern Pines, NC
Posts: 63
Engine REVs high at start after manifold replacement :confused:

I just replaced the exhaust manifold on my 97 TJ 4.0. Whenever i start it now the engine just REVs like someone is stomping on the Gas. i'm not sure what would cause this but i ran into a couple other problems as i was putting everything back together that might be helpful in helping me figure this out.

When i put the power steering pump back on the bolts didn't line up through the bracket and into the intake manifold, so i had to unbolt the bracket from the block in order to get the power steering pump screwed into the intake manifold. then the serpentine belt would not fit around the power steering pump pulley, even when the idler pull/tensioner pulley was fully extended; i ended up having to use a pry bar to get the belt around the pulley and even then its still not completely on.

I'm assuming that when i put on the intake manifold i must've not seated it fully or correctly and that is somehow contributing to the immediate high acceleration when i start the engine. i've checked the accelerator cable and it's not stuck open at all, so i don't think that is the problem.

i'm hoping someone might know what i did wrong before i have to strip the whole thing down again. so any advice or ideas anyone could lend would be greatly appreciated.

oh, and using a torque wrench on those manifold bolts is practically impossible, i don't see how you're supposed to get a torque wrench in some of those tight fit spots.

GDM97TJ is offline   Reply With Quote Quick reply to this message
Unread 01-09-2011, 09:38 PM   #2
Registered User
1998 TJ Wrangler 
Join Date: Jul 2004
Location: Colorado Springs, CO
Posts: 664
Vacuum leak is the most likely source. Since you had bolt alignment issues, maybe the manifold isn't seated well.
NakedJeeper is offline   Reply With Quote Quick reply to this message
Unread 01-09-2011, 09:39 PM   #3
Real Jeeps have dents
CJ7-Tim's Avatar
2000 XJ Cherokee 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 23,536
That's the most common symptom of a massive air leak at the intake manifold. Re-check your work, either the intake manifold is not fully flush to the head or you forgot to reattach one of the vacuum hoses.

Total US debt has increased by 70% under Obama, from $10.625 trillion on January 21, 2009 to $18.005 trillion January 1, 2015.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Unread 01-10-2011, 06:18 AM   #4
Registered User
1999 TJ Wrangler 
Join Date: Nov 2002
Location: Baton Rouge, LA
Posts: 66
i had this happen the first time i replaced my exhaust manifold, and wound up cracking the intake. make sure the intake is lined up on the 2 dowel pins on block at each end of the intake. once you have the intake back on try to hold it flush up against the block and try to slide it STRAIGHT up, you should have about 1/8" of play up and down, if it comes up off the engine it wasnt on the dowel pins.
iceman6533 is offline   Reply With Quote Quick reply to this message
Unread 01-10-2011, 06:25 AM   #5
Registered User
1999 TJ Wrangler 
Join Date: Nov 2002
Location: Baton Rouge, LA
Posts: 66
also i have found that using a u-joint in between the socket and extension (6 inch on the bolts closer to the ends and a 9 inch on the inside bolts) works best. reach under the intake with the socket/u-joint/extension (off the wrench) and put it on the bolt head and hold it there, then install the wrench on the extension and torque to spec. if you have someone helping you, have them get under the jeep with a flashlight to help you get the socket on the bolt head (also can have them stick their pinkey finger in the dowel pin hole to see if it is lined up properly)
iceman6533 is offline   Reply With Quote Quick reply to this message
Unread 09-30-2014, 10:58 PM   #6
Registered User
2002 TJ Wrangler 
Join Date: Sep 2014
Location: Sault Ste Marie, Ontario
Posts: 1
I'm having the identical problem. I have already re-installed the manifolds for the second time and i still have the high revving at start up. My vacuum lines seem to be ok so i have to assume I'm not lining up the intake manifold properly. I looked at where the intake manifold seats on block and it is touching on the top edge but slightly off as you go down . I think the problem is that I didn't hold the manifold tight and square onto the block as I tightened the bolts . I assumed the manifold would seat square as I tightened it but its not happening . I'm going to try again and focus on keeping the manifold square onto the block as I tighten and also on those alignment pins . Regarding torquing the bolts i just torqued them by feel because like you said there's no way to get a torque wrench in that clutter. A friend of mine said that they should be torqued to about the same force you use when installing a spark plug . Something I did to help line up the lower bolts is I marked their location vertically on the valve cover so i had a target when trying to get them onto the wrench socket. I will let you know how I make out tomorrow.
greekroman is offline   Reply With Quote Quick reply to this message

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
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:


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.