Hey everyone. Been a Prius owner for about a year and a half. joined the forums to try to fix my car’s misfire and rough start issues.
I'm working on a friend's 2005 with that problem right now... It showed up dangerously low on oil and the rough running is only intermittent. I added a quart of oil and it barely registered on the tip of the dipstick. The car's due for an oil change anyways, so I'm not gonna waste any more oil and do the oil change first. All the engine error codes can be attributed to a lack of oil and don't return right away. Originally the error code was a misfire in #2 and our local group of hybrid nerds think the recent batch of codes and lack of oil is affecting proper function of the valves which led to the misfire being detected. It's likely a classic situation where people don't realize that taking good car of your car is making sure you check the oil level often. As for your 2010, that's a different engine design. The primary problem being that the EGR valve gets dirty and clogged and leads to rough running at idle due to a blown head gasket. Hopefully you problem is not that serious.
no coolant or oil loss in the ~200 miles or so that I’ve been keeping an eye on it. I completely removed the EGR and intake manifold and gave it a good cleaning. New plugs and coils were the first step. next step is a compression test to rule out a head gasket.
Yeah... How to plan the sequence of maintenance & diagnosis is always a tricky internal debate for me. On the one hand you don't want to wast your time if it's the engine is blown, but on the other hand once you confirm the engine is fine, it's nice to already have most of the work done. Even trickier is when it's your friend's car. For example, I don't want to have to charge my friend for an oil change if her engine is blown. But on the other hand I'm not going to get an accurate diagnosis if I don't address the lack of oil of the engine first and decided it's a waste of oil to add more after I poured the first quart in and that wasn't enough. So oil change seems to be the best approach at this point. But if that doesn't solve the problem and the engine is bad, I just wasted a lil bit of my friend's money. Of course compared to her going to a shop, she's still doing great at saving money.
Welcome, and you've come to the right place. Wealth of information and many members who can help with any issues.
