Idle shake

When my car is idling in neutral or park with a warm engine, it has a noticeable shake. At first I thought it was the 87 octane gas that the dealership put in, but that theory was dismissed when I filled it up with 91 octane. The shake isn't violent and even not enough to make my keychain move, but enough for my passengers and I to notice. My car is automatic, if it matters. Is this normal? Anybody else experiencing this with their LGT? Replies are appreciated! I made it a poll so I can hopefully get more input. -Dan

yep mine shakes just like you noticed, I have 5SMT

that's one of the minor reasons i got a h6, besides the tick, tick, tick,tick......

Seems only sometimes. Doesn't shake in the morning with fast idle.. I think the last time I felt it was after a long drive, parked the car and let it idle for a few minutes while listening to song end.. It's like a mild earthquake, you're not really sure what just happened until you focus. [url]http://www.legacygt.com/forums/showpost.php?p=76318&postcount=6[/url]

I have to admit, running RON98, there is no shake at all. In the early days (first 6 months) there was a bit but not TOTALLY noticable. Personally I noticed after my first service, a lot of these issues did disappear. BUT if you are concerned, take it back to the Dealership for a closer look. All the best. Adam.

Mine did it since brand new, first night I brought it home. Also on the test drive and continuing now, the car bogs if you shift it really fast (and WOT) in 1,2,3. If you shift slower and/or less throttle it is smoother. Mine also has the smelly clutch after a few good slips, and now is starting to make that funny humming noise when I start the motor cold.

Mine started to shake a little after about 10,000 km. It stopped after using some injector cleaner. Not sure if this helped or was temporary.

try to get your spark plugs replaced

MY05 5MT 2.5i non turbo, 4500kms Run 98 RON (Australia) No shakes at all. I do think that if you detect shaking/vibration at idle you should switch to the highest octane fuel possible. For the engine to adapt to the switch in fuel, you'll need to consume about 4 full tanks before the computer fully applies what it has learnt.

Vibration/shake yes.

Wow, although shaking is ahead 2:1, it still doesn't seem normal that a brand new car would shake like that. I know that our car isn't a Mercedes or a beeeeeemer, but the engine shouldn't have that much vibration. I hope that Shane's comment that 4 high octane (91) fillup should at least lessen it.

[quote name='myUsername']Wow, although shaking is ahead 2:1, it still doesn't seem normal that a brand new car would shake like that. I know that our car isn't a Mercedes or a beeeeeemer, but the engine shouldn't have that much vibration. I hope that Shane's comment that 4 high octane (91) fillup should at least lessen it.[/QUOTE] I always use 93

aaww, quit all the whining.. it's a boxer engine! jk, it's nothing to be afraid of.. the air is just cold/dense.. mine still idles at 1k rpms.. so it's not exactly up to operating temps anyways even after 5 mins of startup in a parking lot at 30F degrees.. once the car is up and running, it's perfectly fine at stop lights and such. Keefe

AAAaaahhh shaddup!!! :D CA only gets 91.

no shaking

In the North East US we have 93 octane available and thats all I use. Mine still shakes everday. I've tried 2 different brands already. 3200 Miles and Lots of Fuel.

I haven't noticed any shaking in mine. As a matter of fact it seems smoother than the engine in my WRX.

Mine only shakes sometimes. At other times it idles smooth as silk. *shrug* sqrl b8

Mine didn't start shaking until the recent cold weather, and I have about 5200 miles on mine. It smoothes out completely once warmed up. My WRX shook frequently hot or cold, and was worse with the A/C running.

Further to what I wrote - the octane rating of Australian fuel is expressed using Research Octane Number (RON) and our highest is 98. I think that in the US and Canada, (RON+MON)/2 is used resulting in a lower figure. Don't know whether you should seek the highest RON, the highest MON or the highest (RON+MON)/2, but one of those for 4 full tanks could make a big difference. I used 4 tanks of 98RON when I bought my car and noticed the engine behaivour change quite a bit during the end of using the fourth tank of fuel.

[quote name='shane']Further to what I wrote - the octane rating of Australian fuel is expressed using Research Octane Number (RON) and our highest is 98. I think that in the US and Canada, (RON+MON)/2 is used resulting in a lower figure. Don't know whether you should seek the highest RON, the highest MON or the highest (RON+MON)/2, but one of those for 4 full tanks could make a big difference. I used 4 tanks of 98RON when I bought my car and noticed the engine behaivour change quite a bit during the end of using the fourth tank of fuel.[/QUOTE] Yeah we use the average of Motor and Research octane ratings. The only octanes we get in the Pac-NW (Washington) are 87,89 and 92

With the idle shake, what are the RPMs at that point? Does it smooth out if revs are 1-200 RPM higher?

My Legacy gets lumpy sometimes after its been running awhile. when I purchased the LGT it was glass smooth until I hit about 600 miles. Now after the engine has warmed and if I notice it gets lumpy, shakes. Its no where near as bad as my 02 WRX, but not quite what it was like when new. I do find that fuel quality seems to make some difference. Cheap gorcery fuel more shakes, shell 93 octane smoother idle. Dunno I figure its normal this is after all a 2.5L 4 banger with no balance shafts. IT runs pretty damn smooth considering what it is. You never going to get a 4 banger without balance shafts to run as smooth as a small or moderate sized 6. My dosen't shake as much with A/C off. And it dosen't shake at all at higher RPM's. It just feels lumpy. Almost like race cams..... But 95% of the time its glass smooth, my hats off to subie for doing a good job. Maybe some of us have over stressed our engine mounts? I also found my REX ran smoother when I switched to synth. But my rex always ran rough. I think subaru still has some quality control issues on assembly. my friends rex was glass smooth. my dads LGT also idles glass smooth.

I put 93 in and have 11,000 miles in 4 months. No shakes, just my own jitters when the road starts to feel small. Car runs perfect, stereo sucks but who cares.

[quote name='racerdave']With the idle shake, what are the RPMs at that point? Does it smooth out if revs are 1-200 RPM higher?[/QUOTE]The RPM is at the normal range about 650-700 with a warm engine. When the rhythmic shake occurs, the RPM needle does not fluctuate at all. I'll try to press on the gas a bit to see if it'll smooth out. To better describe it is like to be in a V8 muscle car, but with a 4 cylinder engine - it's very rhytmic and in sync with the motor. Again, it's not an uncomfortable shake, but noticeable enough. I think I'm just being paranoid. I have another 35,400m of warranty left.