I am trying to identify a vibration I have - I cannot work out where or what it is.

What Ive done:
1. replace motor mounts - Brown Dog rubber (just niice and tight, as the Brown says)
2. transmission mount replaced (again)
3. Spark plugs
4. Mopar IAC replaced
5. Mopar TPS sensor
6. Cat replaced
7. O2 sensors replaced
8. Spark plug wires / dizzy cap replaced
9. Idler pulley tensioners replaced

What needs doing:
Shocks have had it, replacing shortly with IRO lift, bilsteins

What Im experiencing:

bad vibes coming through at idle only, AC off - wing mirrors shake slightly

AC on - shakes / vibes is worse - I need a dental medical plan

I checked the Harmonic Balancer - no play

AC blows nice cold air, no noise from pulley (bad bearing sound)

What could be causing the vibes, especially with the AC on??? Can the bad shocks do this at idle? Map sensor??

 

No not the MAP sensor, or any other sensor. Vibration is usually resonance, especially since its at idle and only with AC on? What is your belt tension like. Do you hear any pulley noise when idling?
Probably dive into checking all fasteners around the ac compressor, transmission mount (you stated the engine mounts are snug) .
Your harmonic balancer still could well give you vibration if its under par. Yes, it might not have a huge play, but does it have a wobble? This is usually a sign that it is starting to give (the rubber) and its wise to replace it ( in the middle of doing this myself). Vibrations in the crankshaft can cause a lot of costly damage down the road...
Its suggestive that the ac compressor might cause some sort of drag out of spec, since its causing the vibration to occur...

 

The serpentine belt has tiny fraying on edges, i can twist it slightly. I cant hear noises when idling, motor is quiet.

 

This is doing my head in....i cant figure it out. The vibes were not there until i changed the motor mounts from stock to brown dog. Ive played around tightening and loosening the through bolts daily. No freaken change.
Am i best to just get some factory mounts?

 

Vibrations at idle are normal for the Brown Dog mounts.
Very noticeable compared to stock mounts.

 

You may want to check the integrity of the mechanical fan bearing in the AC Compressor mount bracket.

Loosen the drive belt enough to free up the fan pulley then grab the fan and rock it up and down and from side to side.

 

^^Start here^^
You're going to have to get in there and start wiggling all of the rotating parts to see if any are loose, bent, out of round or has bad bearings.

 

Try tightening your belt. If it's too loose but still tight enough to work, it could produce a "humming" sound. You should replace the belt if it is fraying.

 

Mechanical fan is good, i checked it last weekend when i replaced the idler pulleys. Brown Dog just told me i still have the through bolts on too tight.
Wouldnt it be the trans mount if it only happens in gear?

 

Simple enough to remove the fan belt and start the engine up to see if it is related to anything belt driven (i.e. compressor, fan bearing, alternator, etc)... If it remains with the belt off, then you know it resides else where... Being that you won't have any water circulation during this test, I would advise it be run only long enough to verify vibration is still present or not (less than a minute of running)...

 

If it helps my tj didn't have vibes until I installed those same mounts. Not saying they are bad just stiff.

 

My idle sits at 500...if i increase to 800 its smooth as silk. Is my idle too low?. I can handle the vibes with no ac but is not tolerable with it on...unless im moving.

 

Possibly time for a IAC cleaning... Read post #2 in the below URL...

http://www.jeepforum.com/forum/f11/2...dling-1301807/

 

Ive cleaned out the throttle body. What i did notice is the battery voltage drops 5 secs after start up by 2 volts and with ac on it drops to 10 while driving..at idle it drops again. They other day i had doors open for 10 mins and it wouldnt start?

 

I'd be doing a charging/battery system test.