slight vibration
 

I have this very slight vibration I can feel through the gas pedal, brake and steering wheel under some conditions

The vibration falls below feeling level after the idle drops all the way down when stopped in gear, and fades away (but may still be there) above say 3 to 3.5K rpm.

Definitely worse under acceleration, but can still feel it when sitting in park/neutral and blipping/revving the engine.

Steady state cruising and can't feel it (well maybe at about 1500 rpm - hard to tell - I'm losing it on this one - it's like after I got my tranny back and all kinds of imagined things...you who have done it know what I mean).

Watching the engine shows no abnormal shaking like a broken mount. Changed spark plugs, no improvement. Cleaned throttle body with spray in 3M product, and used same cleaner on MAF wire just in case. Added a can of Tecron to gas but only have put on about 50 miles since that.

No check engine lights.

tia of course.

There was a thread awhile ago about vibration in the gas pedal. Have you searched? I am not sure how it ended up. Seems that it would be difficult to get the pedal to vibrated.

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Mine has had the similar vibe since I bought it. I've spent a few minutes here and there looking for it, but have yet to put my finger on the problem. Maybe I should put a little more effort into the solution. Now if I could just find the time.... ;)

thanks, yes I did a search, but all the threads I looked at seemed to imply the car needed to be moving, which might implicate the CV, etc (any rotating part whilst moving). Mine does it in park or neutral too. From that I assumed engine or a portion of the tranny (TC and who knows how far back). I drained the tranny pan and put in 5.5 qts of new M1 ATF (fluid looked good and no burnt smell), and as described above, changed plugs, clean TB and MAF, and put in some techron.

Now have another 50 miles on it, no improvement. :confused:

Well I sincerely hope that whatever my problem is, that it is the same as yours. I base that hope on the idea that if it was something that either a) if not fixed means big bucks later, or b) if not fixed means may be spending quality time at the emergency room. Please let me know if either a or b are not applicable in your case :D :D

Lee

If Beav has it, and is not worried by it, then maybe paranoia is redundant in this case.:D :D

Two things seem likely culprits, or rather, two types of thing. It can be a misfire in the engine, you are already looking into this with the plugs change. Perhaps it is a misfiring coil, or a bad lead?

The other type might be a rotary component that is not balanced. You would suspect something big, possibly heavy, like the flywheel. Say for instance if the ring gear of the starter had chewed a tooth off the flywheel?

Just thinking out loud here, but if the new plugs made no improvement, maybe it is a rotary component out of balance, or a bad mount on the engine or tranny.

Joe

I notice mine under acceleration, and also feel road shock through the gas pedal and in the shifter. This is in addition to the light but noticeable 'buzzy' vibration. At times it's barely perceptible, other times it's easily noticeable.

Typically manufacturers use cable linkages on these items for their simplicity and because they normally don't transfer driveline/suspension NVH (noise, vibration, harshness.) It doesn't seem to be working here. My current guesstimates are lying either in a front hub bearing, the engine torque mount or (hopefully not) a side bearing in the diff. The buzziness of the vibration, coupled with the change in intensity with road irregularities makes me lean towards a hub bearing (multiple balls rolling over an imperfect race causing the buzziness.) The speed of the vibe just makes me feel that it has to be a ball or roller bearing. The exhaust could possibly cause a buzzy vibe, but the road shock doesn't factor in properly. When I get a chance I'll pop the axles out of the hubs and do a 'touchy-feely' inspection.s

After a little more thought I've ruled out the wheel bearings, as you stated it can occur with the car parked as well. That indicates that the cause of the pedal vibrating (and the shifter has a noticeable vibe if you have your hand resting on it) is something that is causing the vibration to transmit to the firewall. I've been suspecting that my engine mounts are sinking, maybe they're squashed to the point that they are allowing the engine to pull the torque strut (behind the throttle body) and load it against the firewall. Hmmm.... maybe I'll just remove the strut and see if anything changes...

I think I've just had one of those live & learn things. I didn't know the mounts could squash. Guess I've not changed one since my V-8 days, when they usually were good or the rubber had separated from the metal.

This sounds like maybe the most promising yet.

p.s. Could a tranny mount do the same thing? Mine doesn't make any clunk sounds like others have said happens when accelerating in reverse. Do you have any idea how hard it is to change the engine mounts, i.e., a little jacking and unbolt - or pull the engine kind of thing.

They are really easy, but pricey. The SVX uses a 'liquid' filled mount (read: not cooked all the way through ;) .) Mine actually weep a bit. My 4.0 Cherokee's mounts had sunk. I just replaced them a few months ago and it made a world of difference.

I fooled around with it a bit this morning in the driveway. The torque strut didn't seem to have any perceptoble vibration but the low side a/c hose did. In fact it was the only item that did. Now I have read TSBs for other cars where a/c lines, heater hoses and radiator mounts create vibes in steering wheels, dashboards, etc. I'm just not convinced enough to evac the system and disconnect the hose to find out. I have noticed that I can feel road irregularities from the RF wheel through the pedal, I'm not sure if it occurs on the LF as well though. I guess I'll have to go shake up some oncoming traffic a bit in order to find out. ;)

Holy 'lots of Ben Franklins' Batman! You aren't kidding. I looked up the part/price on SubaruParts.com - $158 each. I'm sure no aftermarket mounts are available either right?

Beav,

While I was at Subaru of Jacksonville they had an tech explaining all about the new STI. One interesting comment was made that I'd like your opinion of. That comment was that aftermarket parts are generally fine, but if there was a single item to get OEM even though it was available on the aftermarket, that part would be the PCV valve. Claimed the flow characteristics were critical.

It could very well be. Some cars have touchy parts. Fords have always (in my lifetime) preferred OE temp sending units. ... uh...I'd give you more examples, but somebody just came over with a box-o-wine a few hours ago (no, it wasn't Ron ;) ) and my memory has left the building. hic :D