good vibration

[honda12]

well its really not a good vibration. my 93 grand cherokee 4.0L has a nasty vibration at idle and as soon as i increase the rpms around 200 it disapearse and the vehicle drives fine in all situations untill the idle drops again.(idle is around 500 to 600rpms in drive.)the lower the rpms the worst it gets for instance in drive and the wheel turned all the way to lock with the a/c on is the worst.some have said it could be a vacume leak but it just passed smog with no trouble and gets 18mpg.the harmonic balancer looks ok. i looked into raising the idle but the sticker under the hood says its not adjustible and didnt have a spec to go by.please tell me this is a common problem and its really easy to fix.

 

[Jackhill442]

I have seen it happen many times. Just raise the idle slightly, that will fix it and not harm anything. Regualer Cherokees idle higher than GCs so they don't hafe this prob. Forget about smog stuff, it won't make a difference