I need sone help. I have a 2016 Prius V with 270,000 miles, 99% freeway driving . MAJOR service about 30,000 ago. Been running perfect. Until ... a while back I hit the start button and got a violent shake. Hit stop. ran OBD and got CYL 2 misfire. Fluke? Started again and all good though got a couple jerks like a miss but then perfect. Now, a week or two later I get similar but much worse. Ran OBD and got "multiple random Cyl misfire" Haven't tried starting since Thinking at 270,000 ... maybe coils? Anybody seen this? Any thoughts what it might be? Any help much appreciated.
Typical Gen 3 head gasket failure. Coolant leaks past the head gasket into cylinder #1 or #2. This causes misfires on cold startup of the engine. Check the engine coolant level in the plastic reservoir. I am amazed that the engine made it to 270k miles without a head gasket failure earlier. Do a search on this forum. You will find hundreds of threads that discuss the head gasket failure on the Gen 3 engine.
Coolant loss will be slow at first with occasional violent rattles on startup. Spending money on plugs, coils, injectors or egr cleanings is 98% a waste with this problem. A replacement engine is best but if you go with a head gasket repair do it quick before an overheat forces the issue. If you wait too long “Hey Walt… they want to wait and see if it gets worse…” How to check Car Care Nut HG Borescope at 7:40 If Mendel thinks an egr cleaning is in order Start with no cost egr block flow test
How can it be coils; don't they fire all the time when the engine is running? I've never seen cold coils start firing when they warm up. I've seen them intermittently fire or stop firing when hot or they are dead all the time. From what your describing; they are neither. You can easily verify by switching #2 and #4 coil. If problem moves; it's the coil - if it doesn't there's something going on with #2. The only difference between a cold engine and a warm one is fuel mixture and aluminum expansion. Rich when cold, leaner when hot. This is a well know issue with the gen3's. Most likely electric water pump and head gasket failure. You may want to contact; hybrid pit stop and get it properly diagnosed. They have a good reputation for clean, fast, and fair prices. Full disclosure; I haven't needed their services and have no affiliation with them. Good Luck....
