How do I know when I need tune up because when my civic idles it shakes and vibrates in the inside, but when its warmed up its fine and also the steering wheel shakes a lot when it idles too.
What's your gas mileage like? How does the car drive in gear? Does it hesitate or bog?
I don't think shaking or vibrating has anything to do with a tune-up. My car does it too but only because it's old and worn. The plastics rattle, exhaust rattles, etc.
You could even take it to your local mechanic and have them check it over real good to make sure everything is ok, and if you need a tune up. And go from there