I purchased my Prius 3 six years ago used with 64K miles. It now has 192K miles and has needed nothing except rear calipers. Recently I have noticed it bucking or trailering at low speeds. Barely noticeable but I can feel it. It idles smoothly and I don't notice it at full throttle. Mainly at 45 mph and below. While starting it has sounded like one cylinder was skipping but this has only happened 4 or 5 times since I bought it and it hasn't done this in over a year, original spark plugs. Ideas? Thanks
This could be the ol' clogged intake manifold EGR runner. You get misfires in situations where the EGR is open, so I think that means not at idle, and also not at decent throttle. It'll be only when the engine kicks on while driving, but at lighter loads. From my experience and what I believe is mostly the case is that cylinder #1 runner gets clogged and creates a situation that causes cylinder #4 to get extra hot (or extra gasses... or something), so a quick check is to see if cylinder #4 spark plug is darker than the rest (might as well check them all at this point). If it comes to this, you've opened up the EGR system can of worms and might as well clean the whole system. Check out the links in Mendel's signature.
