Update on my "head gasket" issue (=not a head gasket issue)

This classic story deserves to get recirculated every now and then. It's about a Prius that a shop got hold of for cheap because the owner really had let it go for scrap price, and a careful diagnosis led to one spark plug that fixed it.

The way a Prius engine and transmission are coupled, any cause of engine misfiring can lead to banging that sounds like the end of the world.

 

Even a perfectly heathly near new Atkinson engine can lead to some pretty strange noises... I'm grateful for that because it's why I suspect someone sold my 07 at 100K and now I'm at 300K with still no issues any only basic maintenance.

 

This is not a common issue for Gen 2 but it is not an exception either. I have seen 2 Priuses with a bad injector and one in the initial stage, shuddering for half a minute on cold start.

 

The injectors can get trashed by putting gas with insufficient detergent through them. That is, not "Top Tier" or an equivalent. It used to be a big problem. I think all the major gas brands are "Top Tier" now, so not very common anymore. But if you buy at Sam's Club or some little independent station heaven only knows what is in the tank. Most likely it is "Top Tier" too, but there's nothing to prevent the refinery from doing "Chevron's order is full, sell the rest of this batch to the secondary market, and hold the detergent package."