So I ran over to Orielly and rented a compression test kit. I tested each of the cylinders 1-6.

Cylinder 1 was 70
Cylinder 2 was 80
Cylinder 3 was 90
Cylinder 4 was 80
Cylinder 5 was 70
Cylinder 6 was 80

I did also notice that after we finishing turning the engine 6-7 times, the pressure gauge immediately started dropping down. I double checked all of my fittings, etc and made sure the compression test hose and gauge were tight.

So....what are my options? Could it be my compression test kit? Could those readings plus the immediate lose of pressure shown on the gauge indicate a cracked engine block? I think it's the compression tester itself that's the problem, not holding compression or something.

 

The compression checker should have a 1 way valve in it. That meaning after you crank it over, the needle should never drop until you hit the air release button. You might have got a dud from them. If your compression is really what the gauge said, it wouldn't run.

 

@5-speed. Agreed. I went back over to orielly's and dropped it back off. Guy said "Huh...you aren't the first person to say that". I just shook my head. I went ahead and just bought my own brand new compression test tool kit.

 

Haha i am not surprised. Test again with the new set and post results.

 

So I rechecked with my new test kit and I got the following values

Cyl 1 140
Cyl 2 140
Cyl 3 150
Cyl 4 160
Cyl 5 150
Cyl 6 150

All are within the 120-150 pounds spec except #4 but I'm not really concerned (at this point). My biggest concerns that I wanted to figure out was a. my jeep is idling REALLY badly and b. before I put any more money in this jeep, I wanted to make sure my engine wasn't hosed.

 

Those numbers look fine to me. For rough idle there are plenty of palces to start.
Plugs - Champion copper or NGK
Cap
Rotor
Idle Air Control
Vacuum leaks
Coil - I had a marginal coil cause really bad idle when hot
Spark plug wires
Make sure each cylinder is firing by pulling each plug, attach the plug wire and hold the plug by the block. You should get a fat blue spark for each one.

I'm sure others will chime in with other things to check

 

@dzywicki

Thanks for the input. This was just my first initial test of the engine to make sure that nothing was majorly wrong. Didn't want to stick a bunch of money replacing other things if the engine was bad. Already had a tuneup and head

I've got a laundry list of things to do.

Replace power steering pump
Replace engine and transmission mounts
Replace the IAC, O2 Sensor, and TPS sensors, whatever replacable sensors there are.
Do my diffs
Undercarriage cleaning and coating.
Transmission flush
Replace Fuel injectors
and round and round until my Jeep runs like the fine tuned beast it should be.

 

Looks like a great plan.
I wouldn't worry about replacing injectors if you're worried about money. IT's a good idea to replace the orings though.

It is pretty amazing how well the 4.0 will run when you replace all the worn parts. If you are going to all that trouble, you may want to check your distributor (if you have one). The shaft bearings will wear and wobble. Also worth going through the suspension. the front end is pretty easy to rebuild.

Be careful on the TPS screws. They are loctited in there and can be very difficult to get out. I have found it easier to just remove the throttle body completely. Then you have easier access to the IAC and TPS. Just remove the air intake tube and then it's 4 bolts holding the throttle body on. IAC screws are easy, TPS ones are not (do a google search).

 

Yes, this is often overlooked. When it gets bad enough, it will wipe out the cam sensor, which gives symptoms which are very similar to a bad crankshaft sensor.

New distributors will usually come with a garbage aftermarket cam sensor, so buyer beware.