raclaymore

I have a 2001 xj. I just got done doing a motor swap to a 4.7 stroker. I also got rid of the coil rail and went with a coil pack from an 02 viper. The jeep starts fine and will idle at 900-1k rpm for around 1-5 seconds then all of a sudden it starts skyrocketing and I shut the jeep off just before the rpms max out. Any ideas?

Hayden98XJ

I've got the same problem just minus the viper coil swap. I was recommended to check and make sure the timing is set right so i'm hoping to tear into it and find if that's the problem this weekend.

cruiser54

Good sized vacuum leak because the intake manifold isn't fully seated as it's hanging up on a dowel.

raclaymore

The timing is good for the 5 seconds it idles it don't backfire or anything weird but then the rpms max out I am hoping it's just the IAC it also has a 70mm throttle body and I had to swap over all the stuff from the stock one so I may just put the stock one back on and see but I want to get a list together of things to check

Hayden98XJ

I installed my intake manifold with the motor on a cherry picker and everything else stripped off of it. I was pretty sure it was installed right. Would an intake manifold leak cause it to shut itself off?

cruiser54

I thought it was revving and YOU shut it off.

raclaymore

I did that's another guy posting with the same problem

cruiser54

That's how threads get mucked up.

You shut yours off then?

raclaymore

Yes

cruiser54

It's very common for the intake manifold to get hung up on a locating dowel and seem to torque down fine when putting things together.

Hayden98XJ

Yeah my bad didn't mean to thread-jack it just seemed like we were having the same problem.

cruiser54

No biggie.

raclaymore

Now she runs good it was the aftermarket exhaust manifold that was pushing on the intake manifold. My dad told me to use a cigarette and blow it down the throttle body and see where it comes out. I took to he aftermarket on off and put the stock one back on. Problem solved thanks for the hell yall