I replaced my cracked exhaust manifold on my 99 Jeep Wrangler 4.0L (I-6). Note that this is really probably the 2nd time I try such a large job (at least I usually just deal with oil changes). This required the removal of the intake manifold also (because both intake and exhaust share the same gasket). I made sure I removed everything carefully. I disconnected 2 electrical connections and about 6 or so hoses, and of course the fuel line.
I re-tightent the bolts according to the sequence suggested (center bolts first and then the outer). I tried to turn the jeep on, and the engine just rev'ed really fast to redline. I immediately turned it off (the first time probably let it run for 5 seconds). I double and tripled checked the vacuum houses and all the connections I touched during the replacement of the exahust manifold. Note that I did not replace any hoses, except for a connector from the air intake that I broke while trying to remove it. I still need to check to make sure I torqued all the bolts to the correct amount. I tried turning it on about 6-8 more times to see if It would eventually come to a normal idle, but it never did. I actually did not let it run more than 1-2 seconds since every time I turned it on, it revs so fast, almost as if I were pressing on the accelator. I did checked the throttle, and its not stuck.
My question is if a leak in the gasket or a vacuum hose will cause this problem? Or what other things could I have screwed up while replacing the exhuast manifold? Any suggestions I can try would be very helpful.
-Juan