2010 Prius engine misfire intermittently

Does the missfire happen in one cylinder only? That case it can be tested: you swap two coils and if the missfire moves, then it’s the coil. (It happened to me with my Avensis, it was OK at certain rpm, but under load.)

 

yes which cylinder is misfiring? do you get P0301, P0302, P0303, P0304, P0300 or a combination of these?

as it's probably just one cylinder, swap coils between that cylinder and an other cylinder, swap fuel injectors to another other cylinder, and maybe swap spark plugs with the remaining other cylinder. Clear codes and drive until misfires are detected again; whichever cylinder the misfire is detected in will reveal the culprit. Or rule them out if the misfires remain in the same cylinder.

 

Only do one thing at a time, or you won't know which part if malfunctioning...

 

if only one cylinder is misfiring then whichever cylinder starts misfiring afterwards should be a good indicator of the culprit. If only cylinder 3 is misfiring, and you swap ignition coils with cylinder 2, spark plugs with cylinder 1, and fuel injectors with cylinder 4, and the misfiring moves to cylinder 4, guess what is likely the culprit?

Swapping one thing at a time may be more reliable but if the issue is intermittent and doesn't often trigger misfire codes it may take too long to diagnose; I think swapping all three would be fine.

 

as long as you feel good about it......

 

[273k miles on my 2010 and lots of misfires. Reduced the water pressure by removing the o ring on the water cap and ,at 3k miles later, no misfires anytimeQUOTE="Salman Tariq, post: 2954449, member: 179029"]I had intermittent engine misfires which would go away itself after sometimes or after car is powered off and on. But few weeks ago I was driving on highway n it started and it kept doing that and engine light came on as well for first time. I parked car for Abt 1 hour and then it was fine no issues at all. Took to mechanic next day he cleared the code to see if it comes back but it didn't but after few days I noticed misfiring again randomly while car was in motion. When on battery it's fine obviously. No engine light came. Took back to mechanic he said he will start off with changing spark plugs n air filter as I didn't get those changes since I bought the car 2 n half a year ago. But after a day of getting those changes it was still misfiring but still no engine light. I added fuel cleaner with full fuel tank and went for a long drive Abt 200 milees and no issues at all infact car ran very smooth. Today after Abt 3 days of using fuel cleaner it started misfiring again. It happens when car is in motion not when I start the car. No engine light still. I mean car runs absolutely fine n smooth but just when misfiring happens i feel bit shaky. Mechanic advised me to try adding 50% super extra fuel along with regular as normally I just put regular. Mechanic tried reading thru machine but nothing came up he said normally it will only show when the engine light comes on but it only came up once only n never after that.
Please advise what could be the issue. Thanks[/QUOTE]

 

@Bob Pic can you clarify: how many miles on your car? Is it 273K? Your post is confusing, with the broken quotes.