Redlining at start up

[TheGarbs]

I have a 2000 xj with 200,000 miles on it. the head gasket blew on it so I took it all apart and then then let it sit for a while. Then finally put it back together. Now it fires right up but revs all the way up to redline and stays there. What could it be?

[Pookapotamus]

is the throttle cable jammed or routed incorrectly? is the butterfly stuck open some how?

Pook

[prcjeep]

maybe double check the installation of the TPS...

[bigjim350]

I would lean towards what pook said. Had a butterfly stick open on me before. Take your air intake off of the throttle body and see if you can see it stuck open.

Sent from my nerdy smartphone

[4.3LXJ]

A bad vacuum leak will give high revs, but I never heard of it red lining. Are you truly that fast or does it just seem like it?

[XJ Wheeler]

Check all vacuum lines too.

[TheGarbs]

All vacuum lines are closed and the butterfly is too. It seriously bounces off the the rev limiter. I was getting a code for throttle position sensor volts too high so I replaced the sensor but still nothing

[4.3LXJ]

If you have the butterfly closed then you have a serious vacuum leak. Check the intake gasket and the brake booster line. Brakes working alright?