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....
I've had it since late 2020. Its obviously (now) the head gasket. at 80 yrs I've had lots experience with engines. Pull the valve cover, pull the valve train, pull the plugs, pull the intake and pull the head(s). Used to be a breeze. But THIS is something different.
Hello, Don't know why that sent but: I've put about 150 on it it had 120 when I got it from a dealer. Had a major service at about 30,000 ago. I'm in the process of learning and changing the head gasket now. For me the worst part is just getting to it and getting the harness out of the way. I do have some questions: A) For me it always been all parts on/off sorted by cylinder. Is this the same ie. a bunch of rockers. Do they need to go back exactly as they came off? B) I'll change the plugs, but should I change the coils as well? Thanks, John
It's an overhead cam setup - you don't pull the valve train apart. You do need to align the timing marks and set the timing properly. I would replace the timing chain, tensioner, and guide hardware while I'm there, along with the electric water pump. Those electric water pumps tend to get intermittent pass 150K miles. You won't know that your running hot w/o a gauge and the car doesn't set or store an over temp event or set the CEL. They rarely throw a code and your temp lamp doesn't light up until it's 248+F. Nominal is around 190F. Hope this helps.....
