I got a series of questions

[HeepJr]

1. I put my jeep in 4x4 and once in awhile very rare i hear a loud metal snapping noise have no clue what it is has me scared but 4x4 works fine.

2.my fuel pump makes a high pitch noise is that normal or no?

3. my down stream o2 sesnor was dead i replaced it with a bosh and my engine light came back on and its saying low caty emission levels again down stream 02 sensor inst reading again same as last time any clue?

4. I'm getting a 3 inch lift kit what would you suggest i'm looking at rough country and sky jacker.. any others or whats better?

please help :D

[Mudderoy]

1. I put my jeep in 4x4 and once in awhile very rare i hear a loud metal snapping noise have no clue what it is has me scared but 4x4 works fine.

2.my fuel pump makes a high pitch noise is that normal or no?

3. my down stream o2 sesnor was dead i replaced it with a bosh and my engine light came back on and its saying low caty emission levels again down stream 02 sensor inst reading again same as last time any clue?

4. I'm getting a 3 inch lift kit what would you suggest i'm looking at rough country and sky jacker.. any others or whats better?

please help :D

1. I'd bet it's a stretched chain popping over the teeth of the gears. (Need more info to be sure)
2. Dunno about this one
3. How long since the upstream was replaced? How old is the cat?
4. Everyone seems to favor the Rubicon Express, I put a 3" on the 99 XJ, I think it's fine.

[HeepJr]

1. I'd bet it's a stretched chain popping over the teeth of the gears. (Need more info to be sure)
2. Dunno about this one
3. How long since the upstream was replaced? How old is the cat?
4. Everyone seems to favor the Rubicon Express, I put a 3" on the 99 XJ, I think it's fine.

umm havent replaced it since i bought it and also not sure the caty looked pretty new