My 99 obw developed a bad vibration in gear at idle. This developed a few weeks ago. I have read the threads on this subject and for the most part people just live with it " I put my car in neutral at redlights" seems to be a common reply. And the remedy seem to all over the board. Here is what I have done. Oem plugs and wires, cleaned Iac, ran seafoam thru intake, all new vac lines, pvc new, runs perfect on the road and in park or neutral. I did replace pass side axle about 6 mth ago. inspected the mounts and replaced the trans mount over the summer. Recently noticed the center pin in the trans mount had shared off. Replaced that thinking I had solved my problem.....nope. any ideas? Would an autozone axle start to vibrate after 6 months use? Any way to test and narrow this down somehow? Driving me nuts, used to idle so smooth.

Autozone axles are usually pretty good as they come from the same rebuilder in Mexico that Subaru used.

 

It is quite possible that the axle is bad. The vibration usually starts right after axle replacement, so it is quite possible that the axle went bad OR -

 

You do know the pins are directional?

Are you talking about the drive pin in the axle? Directional? Problem 6 mth later?

Do'nt read your own posts? :-p

 

"I did replace pass side axle about 6 mth ago"

"My 99 obw developed a bad vibration in gear at idle. This developed a few weeks ago"

 

 

Your words not mine.

 

Yes the pin that holds the axle in is tapered(If I remember correctly) and needs to go in in the proper orientation. Otherwise they can work loose and sheer.

 

If not then it is possible it is a bad axle, it happens.

I honestly had no idea the pin was directional. By directional do you mean the pin itself or the hole in the axle? God, the last thing I want to do is mess with that pin again. It was a real b/&%# to get out!

I got it! Just by luck! First I tried to turn up the idle. Just a touch. The ecm didn't like that, kept throwing a high idle code. So I cleaned the map, removed and cleaned the Iac valve . Still vibrated . I then loosened both motor mounts and Rocked the engine with a pry bar. Checked out that axle pin and it looked fine. I was convinced it was the autozone axle.This morning, I decided to change the plugs. They only had about 10k miles but I thought I'd give it a try. Put in new plugs and noticed the cruise control vac hose was cracked. Replaced that (didnt think that would cause a bad idle) and by accident slammed the pass side door. There is was! That rattle! Turns out there is a metal bracket to support the fender bottom. Tnhis rusted at the bottom and was rattling around. Gone! Rattle is gone! Thank god I didn't have to replace that axle again

Glad you figured it out! Noises are really weird and hard to find sometimes! Just as a note, the idle is not adjustable; it is completely controlled by the ECU by modulating the idle air control valve.

Looks like the Iac itself is adjustable. Seems to vary idle slightly and unlike the set screw, the ecm will not correct it.