Shaky tail pipe

[RatLabGuy]

Some time ago, I was at an auto auction lookin' over cars, and this one was idling in front of me. This old guy leaned over and said, look at the tailpipe, how it shakes alot/vibrates in sequence w/ the idle. He then told me that indicates something - but I can't for the life of me remember what it was.
This is bugging me!
Timing off? vavlvetrain problems?
Somebody help me out here....

[Tacoma747]

broken exhaust mounts? :)

[RatLabGuy]

Nah, it was something w/ the motor.

I mean, yes, that clearly would make the tailpipe shaky, but necessarily in perfect since w/ the idle.

[Chris_M]

motor mounts

[90xj]

Sometimes you can see that if the engine is misfiring.

[RatLabGuy]

Sometimes you can see that if the engine is misfiring.

That might be it, misfiring typically comes from timing too advanced?

[90xj]

Can come from timing out of spec, injector not firing, ignition malfunction. There are alot of things that can come into play here.