I have a 2000 Jeep Wrangler TJ, it is a 2.5 L 4 cylinder and I messed up. I went and bought a new exhaust manifold because my old one was cracked and it looked liked a straight foward thing. I took the fan, the fan cover, the power steering pump and belt, and went on with taking out the intake and exhaust manifold. All went well and i put the new one on and put the rest of the engine bay back together. Everything looks right but every time I start my car it starts aggressively reving and I am forced to turn the car off. I know it has to deal with some vacuum line or some sensor or something being put on in the wrong place but i cant figure it out. I cleaned all the sensors with sensor cleaner and I triple checked that all the sensors and tubes went back as they were before and it all seems correct. Does anybody have any tips on how to fix it or what is causing it or who I could call or anything. Its my only means of transportation and im kinda screwed.
2.4 engine revving high after replacing exhaust manifold
- Thread starter oSchenk
- Start date
Sounds like you have a vacuum leak. The most common place after this type of maintenance is the intake manifold not seating properly.
Check around the intake closely. If i remember correctly it's easy to get the intake placed wrong and think its on but leaking.
If it's not the manifold...wish I had a 2.5L to look at but, I'm thinking there are not too many vacuum source/connection points on the intake. Try pulling the lines of off and plugging all of them to see if that's it. If so, you can then reconnect one at a time to narrow it down.
Does it respond to the throttle at all. Is the throttle open like the cable is being pulled even at idle?
Does it respond to the throttle at all. Is the throttle open like the cable is being pulled even at idle?
No worries, as suggested above (unless you left a major vacuum hose disconnected like to the power brake booster) your intake manifold is simply not seated properly. This is a common issue when doing this job so I hate to say it but you essentially have to redo the entire job. Insure you spend enough time, don't rush this part of the job, to insure the intake manifold is properly seated against the head. A leak between the intake manifold and head results in the rpms you're experiencing.
You dont have to take off the fan and fan cover but it makes it a whole lot easier to get them out of the way so you can get to everything else but regarding the power steering pump and intake manifold both have to come off to get to the exhaust manifold
I guessing not a Mopar (NLA) so it's probably a Dorman or similar.
Please note: on numerous aftermarket manifolds the casting where the ex manifold shares the stud with the intake manifold can be to thick and the heavy washer that is supposed to secure both manifolds cannot reach the surface of the intake manifold. Take a look at these locations to see if the washer is not fully seated.
I'd have a look at your factory service manual (you can get it for free in the TJ Resources Subforum) and make sure you're getting the torque & tightening sequence correct. Also look carefully over the sealing surface, make sure there isn't any crap in there preventing a good seal like a nick in the gasket. Though with the symptoms you described it sounded like a pretty big leak, the thing was probably just cocked. Real important to get that tightening sequence right.
Damn, I got an all-caps compliment!
I mean if you’re going to thank anyone thank @Chris, he is after all the purveyor of this forum who makes available all the manuals, data, and knowledge you can get for free at anytime. Just be sure to get your angry-eye grille via his amazon store so he can continue to buy houses with cash all through the western United States.
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