Small Shake at Idle
 

If someone has any idea what's happening here I would really like their opinion.

The car feels fine. When I pull up at a stop light and the engine slow's to idle, I get a small shake kind of like a engine miss, but I'm pretty sure the engine is running well. Here's the rub (so to speak) If I shift it into neutral the shake goes away. The idle speed changes only slightly maybe 50rpm or so. When I drop it back into Drive with my foot on the brake, the shake has, for the most part gone away. It builds back slowly as I sit with the car in gear and my foot on the brake. In neutral it hardly feels like the car is running. But with the car in drive I get the vibration. I haven't heard anyone talk about this before so I'm worried about the transmission.. ( I always worry about the transmission:rolleyes: ) Any help ?


Thanks

Mine does the EXACT same thing. Todd (wawazat??) even commented on it when we went for a "beer run" in my car a few weeks ago. I dont let it concern me, but it would be fantastic if we could figure out how to fix it.

Mike

Glad to hear my car is not the only one with a little vibration -- only at low idle too. If the AC is on -- no vibration. My tech is convinced the motor mount bushings need to be replaced. Will let you know how it turns out.

aloha

nick

Probably a small vacuum leak. I found one in mine some time ago. There's a vacuum reservoir under the right side of the intake manifold. In front of it (towards the p/s pump) is a vacuum hose with a small check valve. My check valve had cracked from years of heat and was just enough of a leak to put a small 'bump' in the idle. See: 'Vc tank' at http://www.subaru-svx.net/photos/files/Beav/5309.gif

Others have found loose intake plenums and manifolds, etc. Vacuum leaks are the most common cause of idle roughness (with no other symptoms.)

Thanks Beav
 

Guess where my head will be in the morning!;)

Mine does this too. I just noticed it last week.

mmmmmmm-beer! Good! Shakes, bad.

Todd

I've found that some gas makes my car shake a little at idle. When I lived in VT, there was a 'discount' gas station that I always bought my gas at. I tried switching to a Sunoco station or something like that, and the shake went away.

When I removed the intake I found that alot of those small rubber vacuum hoses were so brittle they just fell apart. Probably leaked quite a bit up until that point.

?
 

When you say you removed the intake (I haven't had a chance to check the hoses yet), what exactly did you take off? The Intake manifold? If so I may need more than a weekend to get to the hoses....... :( :(

Just the top intake part. Pictures are in my locker. It is not hard to do at all, just plan on having enough extra hose to replace the ones that are cracked and new intake gaskets. If you haven't changed the PCV valve yet, this is a good time to do it.