Engine vibration/shake

[foureyedbuzzard]

Hi all,

Have a question for anyone with some similar experience. Car is a 1998 Legacy Outback, 2.5L, Auto trans, 113K miles. Timing belt was SUPPOSEDLY replaced at 90k(I'm not sure). No maintenance history available. The engine has some light vibration (not enough to spill your coffee, but noticeable) when idling, and this vibration / shaking increases noticably with rpm especially in the 1500 to 2500 rpm range. The vibration is not readily apparent while driving, though with snow tires on all fours it's somewhat difficult to tell. The car is also quite difficult to start when very cold - it kind of chuggs to life after prolonged cranking. I have read other threads here and on other BB's with the following answers:

 

1) Camshaft timing off

2) Injector fouled / fuel management problem

3) Ignition, plugs, wires, coil...

4) Head gasket leak

5) Short skirted piston design

6) Broken/bad motor mount

7) Some subbies simply vibrate and some don't (yeah, BUT WHY?)

 

Any help appreciated. I'm thinking of starting with ignition components, and perhaps moving towards the injectors / fuel system and then timing belt(properly positioned?

 

Thanks,

foureyedbuzzard

[ndsnewleg]

Hi, I'd start by purchasing a Haynes manual, Chilton's is crap. Checking your timing should tell you if you have slipped a timing belt. My 90 legacy (170K) has had a similar problem with uneven acceleration and idle which injector cleaner helped slightly (BG44K is supposed to be the best). Running copius amouts of Sea Foam into the intake manifold to decarbonize combustion chamber has made significant improvements. I may yet do a motor vac on it. I've also been running half a can of Sea Foam in in crankcase since last oil change. Seems to be making a difference in lifter noise. As for hard starting, change your plugs and get some good quality wires. They are probably the originals and it's time. Air filter, fuel filter etc. Run some brake cleaner through the Idle Air Control valve. Throttle position sensor could be problematic. Test/adjust and/or clean. A search on here should give some good steps on how to do the cleaning. Haynes will tell you the rest. There is also a good description on variety of ways to do sea foam. Checking your coil resistance may help though I believe they are rarely bad. Good luck and start with the easy stuff.

[foureyedbuzzard]

Thanks for the reply. I'm going to start, as mentioned, with basic tune up and cleaning of sensors etc. I've read about similar vibration problems before but never saw "the cure" posted. That bothers me a little, but, then again, if she wants to vibrate all the way to 300k I'll be happy. Oh yeah, forgive my ignorance, but what is sea foam?

[ndsnewleg]

Sea Foam is the all purpose additive, oil, gas and intake manifold and probably various other things. It works great. The can tells you how to use it but do a search on this site also. I'm pretty sure there are already good directions on how to run it into the brake booster vacuum hose or the pcv hose. Good luck.

[foureyedbuzzard]

Thanks. Sounds like I should make sure the wind is blowing away from the house!

[bearbalu]

Keep us informed as to what fixes the problem. I have same problem - will let you know if anything fixes the problem!

 

http://www.ultimatesubaru.org/forum/showthread.php?t=28998

[rruge]

This may be as simple as spark plug wires. I had an issue with my 1996 Legacy Outback at about 90k miles. Upon accelerating the motor, it would sputter and shake.

 

 

I suggest this since this is real easy to detect. If you can, put the car into the pitch black of darkness and watch for any sparks around the wires and especially around the coils.

Peace...