I know its discussed a lot, but I was hoping for some advice on where the source of my vibrations may be coming from.
99 xj 4.0l automatic
I recently did a ton of work on it, and it runs great but I have a pretty annoying vibration problem. I installed brown dog rubber motor mounts and after some tweaking of the through bolt, I got the vibes to a more reasonable level.
Now, I feel I have a very loud but "soft" vibration (as opposed to the brown dogs at first which felt very stiff and rattled everything). I'm betting its vaccum related?
Here's what happens:
-Start the car, it idles solid at 1000 and is SMOOTH. Can't feel anything, hard to tell if it is even on. Will stay this way until I put it into gear.
-Once I put it into D or R, RPM will fall to about 700 and vibes will get rough. Still bearable though.
-When I accelerate, it is very smooth and no vibrations.
-As I slow down, no vibrations until I come to a stop, then the vibrations ramp up and become very loud over the course of a few seconds. Accelerate again and they disappear.
-Sitting in park or neutral, the vibrations are still worse than my initial start-up but much less than sitting in D/R with the brakes on.
-The vibrations remain fairly consistent in intensity, but do kind of fluctuate in terms of loudness
The vibrations don't shake everything like did when my brown dogs needed to be tweaked; but I can feel it in the pedals/seat, sorta see it in mirrors, and it is just a very overwhelmingly loud low-pitch vibration/hum. My RPMs are very solid at about 700 (1 tick down from 1000 RPM), but will occasionally bump maybe ~50 RPM in one direction. For the most part, it is very solid.
I have cleaned IAC and throttle body, cleaned intake, new exhaust manifold, timing chain, and a bunch of other things. I have an aftermarket pre-cat O2 sensor installed, and will be switching to an OEM one soon.
I would chalk it up to jeep things, but given that is is so damn smooth when I first start up makes me think there is more to it. Other than that, any ideas where to start?
Thanks!
99 xj 4.0l automatic
I recently did a ton of work on it, and it runs great but I have a pretty annoying vibration problem. I installed brown dog rubber motor mounts and after some tweaking of the through bolt, I got the vibes to a more reasonable level.
Now, I feel I have a very loud but "soft" vibration (as opposed to the brown dogs at first which felt very stiff and rattled everything). I'm betting its vaccum related?
Here's what happens:
-Start the car, it idles solid at 1000 and is SMOOTH. Can't feel anything, hard to tell if it is even on. Will stay this way until I put it into gear.
-Once I put it into D or R, RPM will fall to about 700 and vibes will get rough. Still bearable though.
-When I accelerate, it is very smooth and no vibrations.
-As I slow down, no vibrations until I come to a stop, then the vibrations ramp up and become very loud over the course of a few seconds. Accelerate again and they disappear.
-Sitting in park or neutral, the vibrations are still worse than my initial start-up but much less than sitting in D/R with the brakes on.
-The vibrations remain fairly consistent in intensity, but do kind of fluctuate in terms of loudness
The vibrations don't shake everything like did when my brown dogs needed to be tweaked; but I can feel it in the pedals/seat, sorta see it in mirrors, and it is just a very overwhelmingly loud low-pitch vibration/hum. My RPMs are very solid at about 700 (1 tick down from 1000 RPM), but will occasionally bump maybe ~50 RPM in one direction. For the most part, it is very solid.
I have cleaned IAC and throttle body, cleaned intake, new exhaust manifold, timing chain, and a bunch of other things. I have an aftermarket pre-cat O2 sensor installed, and will be switching to an OEM one soon.
I would chalk it up to jeep things, but given that is is so damn smooth when I first start up makes me think there is more to it. Other than that, any ideas where to start?
Thanks!