Compression low in one cylinder

[scott henne]

Help i did a compression test on my jeep wrangler and all the cyl. had 150 psi except one had 135 psi #3 what would cause that. Its got a pretty bad miss.

 

[Dan Carey]

Exhaust valve

 

[Jezza]

You need to do a leak down test. A compression test gives you a general overview of the cylinders condition while the leak down helps you isolate the problem.

 

[CharlesHS]

You can purchase a Leak Down Test kit on Amazon.

https://www.amazon.com/s?k=leak+dow...ho6ab_e&tag=wranglerorg-20&tag=wranglerorg-20
There are a lot of videos on You Tube explaining how to perform a Leak Down Test (if you don't like this one).

 

[SkylinesSuck]

As others have said, a leak down test will tell you a lot. A bad cam intake lobe/lifter is a possibility.