Shutter when sitting at stop

[Mtndew11]

Hi all, I just got a 2000 Legacy OBW 2.5L with auto and have a little issue. When coming to a stop while in gear, the car will "shutter" like it wants to stall. It has not stalled on me yet. The RPMs drop to between 750 and 500. This only happens when I am in gear. If I shift into neutral the shutter goes away and the RPMs go to normal. I have changed plugs, wires, air filter, pvc valve, ran injector cleaner and added some SeaFoam to the tranny. There is no CEL. Other than this small issue, the car is awesome. Any suggestions? Thanking you in advance...Dave

[nipper]

Clean the IAC valve. A tuneup would be due too, plugs and OE wires, fuel filter, pcv valve.

nipper

[porcupine73]

Hi Mtndew11 and

It's quite possible one or both front axles were replaced with parts store rebuilds before you bought it. Sometimes this results in an odd vibration when stopped in drive that feels like the rpms are low. Shifting to neutral makes the vibration stop. There are some number of reports of this on the soob boards.

To clean the IACV, remove the air filter, then with engine idling, give a dozen or two short sprays of throttle body aimed at the IACV intake:

[nipper]

That was my first thought, but i figured i would go the cheap route first.

What color are your front axles (dont laugh at me, Ive noticed the ones I get from suabru are greenish).


nipper

[Mtndew11]

I just checked through all my documentation I got from the previous owner...both front axles have been replaced. Service was done by a local garage. The documentation does not mention the replacement brand that was used.

I will clean the IACV and see what happens.

[porcupine73]

Ah ok, that could quite possibly be the source of the vibration/stutter. If it was done at a typical non-dealer location, they most likely put in the parts store rebuilt axle. (Actually even at a dealer you're not guaranteed to get a Subaru axle; someoone posted the dealer put in a napa axle without telling the person and then it had this vibration issue).

These parts store axles for whatever reason seem to sometmies cause this vibration. The good ones are Subaru OEM reman axles or MWE axles (someone said lately they've been using carquest axles that have been ok). Now surely someone will chime in saying 'i have xxx axle on and it's great'; this vibration doens't happen with every parts store axle but it does happen with some.

[WayBack]

Originally posted by porcupine73
Ah ok, that could quite possibly be the source of the vibration/stutter. If it was done at a typical non-dealer location, they most likely put in the parts store rebuilt axle. (Actually even at a dealer you're not guaranteed to get a Subaru axle; someoone posted the dealer put in a napa axle without telling the person and then it had this vibration issue).

These parts store axles for whatever reason seem to sometmies cause this vibration. The good ones are Subaru OEM reman axles or MWE axles (someone said lately they've been using carquest axles that have been ok). Now surely someone will chime in saying 'i have xxx axle on and it's great'; this vibration doens't happen with every parts store axle but it does happen with some.

This is something that I'm profoundly interested in. My car has this shudder issue, and I'm curious as to how, exactly, a different half shaft would cause it.
I'm not doubting that the half shaft is the cause, it seems obvious that it is, I'm just curious as to how it could make a drop in RPM and a shuddering.... ? A quirk of the viscous clutch? Would it hurt the tras or diffs to ignore this shudder?

What do Subaru shafts cost?

[porcupine73]

There's a thread on here somewhere where it was discussed. Sometimes when the vibration happens it feels like it is because the rpm's are low. The rpm at idle seems to be lower in drive than in neutral or park in general, not that the axle has anything to do with idle speed.
Spec is 2000 Outback Idle Speed in Park or Neutral 700rpm (A/T)
Didn't see a spec for in gear idle speed....

Subaru reman axles are about $150 on up depending on what dealer you go to (dealers selling online generally charge less) and depending on year and model, whether you return the core, etc.