The mysterious 2k vibration going away by itself...

[AC439]

Hi ya'll !

I have been troubleshooting the 2k rpm vibration (at 4th gear, automatic) for over 2 years and have posted here few times and documenting what I have done. Pretty much ruled out everything except the head. I even called the machine shop few months ago planning to take the head for a rebuild job. The engine seems to put out only 75% of the power compare to the normal condition before the vibration started.

I drive the LXi sparingly, probably about once a week for 15-20 mins. However, few days ago, I noticed less vibration at 2k. Today, I took it out for a spin to the bank. I barely noticed the 2k rpm vibration. Car seems getting up to the normal power and passing slower cars was a breeze.

I know this isn't a technical question or discussion but I have never seen things fix itself, especially persistently having the vibration and it is reproducible. I'm still scratching my head writing this post.......

[2oodoor]

It seems like you already decided this was some imbalance in combustion, if it went away I would check out the distributor.

Read the spark plugs for rich/lean if it was fuel.
Compression/ valve seating would'nt likely fix itself, not with this particular engine anyway.
At first it sounded like the torque converter lock up coming in different which it will do if the TV cable setting was off a bit due to the tune degradation or sudden improvement.

[AC439]

It seems like you already decided this was some imbalance in combustion, if it went away I would check out the distributor.

Read the spark plugs for rich/lean if it was fuel.
Compression/ valve seating would'nt likely fix itself, not with this particular engine anyway.
At first it sounded like the torque converter lock up coming in different which it will do if the TV cable setting was off a bit due to the tune degradation or sudden improvement.

All you suggested were ruled out during the various phase of troubleshooting....

Anyway, I'm always trying to be scientific in my troubleshooting and I had come to the conclusion of the head. The vibration started right after three head bolts (middle 2 and the one to the right of the lower middle head bolt) were tightened with an inaccurate torque wrench (probably over torque).

But somehow it resolved itself and I will take it and celebrate.

[Dr_Snooz]

Three cheers for problems that fix themselves!

[Dr_Snooz]

Hey, where did the clinking beer mug emoticon go???

[conozo]

:cheers:

[2oodoor]

Man goes to the dr and says "my neck always hurts" dr says he noticed the man was walking funny so he checks his gate and asks the man about his feet "oh yeah doc my heel been bugging while back now I don't pay it no mind" so the dr checks the guy's foot, not pretty but nothing obvious so he orders a bunch of tests. Man comes back in a few days and the dr tells him he didn't see anything wrong in the xrays & scans, man says " doc you ain't a going to bleeve this" (yeah that might not be a word, it's for effect) "I went to my uncle's place back east and he gave me a new pair of boots cuz he seen the nail sticking out of the heel my old boot what I been trying to fix" dr ask the man how his neck is any better but before he can finish the man says" but hey doc ever since I got back home my neck ain't bothered me a bit, I reckon it just fixed itself!"
Dr looks away acting like he's checking his notes and says "well sir miracles never cease, you take care now "

I guess we'll never know why

[AC439]

Definitely cheers ! I'm off today so just took the car out this morning shopping, running errands etc. Drove it for 30-40 miles.

I shouldn't have said the 2k rpm vibration is totally gone but it has greatly reduced to a point that I would have to pay attention to feel it. Before it fixed itself, it was so noticeable and uncomfortable to drive because its always there and the car felt like losing 25% of power. Now the power is back, maybe not 100% but feel much more normal like few years ago before the problem began.