Replaced freeze plugs and now my engine skyrockets on start!

[bubbaguy]

Hello everybody, I recently replaced my freeze plugs on my 98 XJ and afterwards my engine hasn't been able to idle normally at all. On start the engine shakes violently and quickly revs super high until I cut ignition. It revs so fast and hard it feels like it's not even going to stop! I don't know where to start the troubleshooting at this point. I cracked an evap vacuum line in the process but I replaced it and I'm still experiencing the issue.

I've also messed with the order of my fuel injector plugs, and while it does seem to change the severity of the rough idle, no combination gets close to solving the problem. Thank you for any advice!

 

[bubbaguy]

My current thoughts are that I may have misaligned the intake manifold slightly, some of the washers don't seem to be sitting evenly on the underside of the manifold. I also found one loose bolt in the rear that I tightened down, but no luck. I'll pull the manifold tomorrow and try to realign it after checking it over for cracks.

 

[sidewaysstarion]

Yeah, it sounds like you didn't get the intake back on the dowel pins.

 

[old_man]

x2 on the intake leak.

Personally, I also spray the gasket with CopperKote to seal.

 

[bubbaguy]

Yeah, it sounds like you didn't get the intake back on the dowel pins.

Yup, that's what I get for trying to finish the job in a hurry. I ended up breaking off a piece of my intake manifold so I had to make a stop by my junkyard for a replacement, but after getting that one in my Jeep runs great again!