P0302 cylinder 2 misfire detected

You should take this car to the dealer to get a proper diagnosis. This mechanic you brought it to is just trying to empty your wallet. The code is a misfire engine code, and they are telling you it's your transmission. It's an engine problem, not transmission.

These cars are notorious for a head gasket failure. So you might get that bad news after a proper diagnosis

 

Pull no2 spark plug See water droplets on that plug end or tip look carefully at the ceramic China portions see droplets smell then smell pink water jug in car ... me smell eh?? Coolant in cylinder bore or hole . I just went through this . Just recently 2013 208,000 miles no 2 same as yours . Tried head gasket meccie missed fissure crack in piston crown . JDM engine ordered. Installed

 

how many miles on her?

 

Is engine coolant level stable in the reservoir?

Have you ever heard of EGR cleaning? Best done every 50k miles, and dealerships won't even tell you about it, let alone do it. (More info in first link in my signature.)

 

Mechanic's diagnosis is NOT consistent with symptoms, nor is it consistent with what usually is broken when these symptoms come up. Call 'em up and tell them that engine misfire error code is not a transmission problem and they need to look at it again.

 

I think failing head gasket has lead to broken damper, twixt engine and transaxle. But yes, just collateral damage.

 

What is OER?

If the mechanic has not seen this early head gasket problem before and is just going by the noise, it is easy to think severe mechanical damage. However a typical early gen3 head gasket leak tends to run fine after it warms up. A severe damper or planetary gear failure won't smooth out and run fine. Warm it up and test it.

If you need something expensive it is more likely to be an engine.

To understand this better, a coolant leak into the cylinder will foul out the plug causing a misfire. This causes the transaxle to lose sync with the engine which is critical 100% of the time when in Ready. The damper slips causing the metal to metal sound. Lost rpm sync goes away once the plug starts firing again. If it does not go away quickly then it could be a "hard" misfire caused by plugs or coils.

A permanent misfire due to a bad plug (possible) or coil (uncommon) can cause a continuous "rattle" that does not clear. Changing the plug and coil (or moving) will id this possibility. But if it clears just by warming it up, it is typically the hg. While not recommended long term, a coolant sealer that clears the problem is also definitive. Sometime a borescope inspection will show a steam cleaned piston. But that test and a leakdown test is not definitive if it passes early in a hg leak progression.

 

Those guys that made that video are the experts in the field.
Go to their web page https://www.gasketmasters.com/
give them a call - explain and ask for a recommendation in your area.
I swear I saw some affiliate shops in TX a month or two ago that are not listed now.

 

I have a Gen 2 Prius that does this. Could this be caused by dirty injector? I felt the grinding feeling today when the car was in drive and waiting at the stop sign. It went away when I put in in park, but again I felt it in Drive. It went away when the engine warmed up.

What it felt like? (Almost like when the brake rotor is rusted and you brake coming to a stop). My plugs are new and I don't have a coolant leak (120K miles), so my next item is cleaning the injector.

 

Any Prius where the engine is misfiring—for any reason—will make a horrendous racket from the transmission that sounds like it is banging itself to smithereens. The reason why is explained in this article, especially under "why the knock?" on page 4. There are heavy electric motors in there that the car's computers are trying to keep spinning in exact synch with the engine rotation, and when the engine misfires, that doesn't work out.

A nitpick, the damper slipping in there is not what makes the horrendous sound. The damper is put there to slip in just such circumstances to protect things, and the sound would be even more horrendous if it did not.

However, if the misfiring goes on long enough, springs in the damper can be pounded to bits and fall out (you can scoop spring bits out of the bottom of the bell housing), and with the springs gone, the sound will be even more horrendous. It can eventually cause the transmission input shaft to break. (Once that happens, you won't even be able to start the engine, because in a Prius, the transmission is what does that. The glass-half-full version: if you can still start the engine, the input shaft hasn't broken yet.)

So if this mechanic is thinking "I shouldn't troubleshoot this misfire, because the transmission sounds horrendous", it's possible the mechanic just doesn't understand that's the way things always sound in a misfiring Prius. You could send along the article linked above. (In that article, an owner let a Prius go for scrap price, and the issue turned out to be a single bad spark plug.)

On the other hand, it's possible the mechanic has additional evidence that there really is a transmission problem.

 

I am having a issue with cylinder 2 miss firing as well, this happened after changing the timing chain gasket, I released the tensioner and verified everything was still on time. What I did do wrong was start the vehicle without putting the spark plugs in *bonk*. After putting the spark plugs in, the major knocking and miss firing stopped but now am getting a p0302. Could this be because of un burnt fuel fouling that spark plug, from the engine running for 30 seconds with no plugs installed? Sorry guys just trying to get my 5 post so I can be seen lol

 

Have you moved the ignitions coils to different locations to see if misfire moves with it?

 

Not yet I am going to do that tonight once I get home. I'm hoping it's just a coil or spark plug and not the new freaking head gasket lol

 

When/why did this happen? What's the miles?

Looking through your posts, see you've mentioned head gasket replacement several times. Can you give more info? What symptoms lead to head gasket diagnosis?

There's a question I'd like to ask, but I don't want to "lead the witness"...

 

198000 miles, So about a month ago my Prius started developing a gnarly misfire at stop lights, throwing P0301, so I replaced cylinder 1 spark plug and coil pack, didn’t fix it. A week later it was really low on coolant, and now had p0302 and p0301 ,and no visible leak. At that time I decided to tear into the head and when doing so piston 1 was washed….

Had a valve job done on head and reinstalled. While I was there I replaced both timing chains (oil pump chain), all the guides, new crank sprockets, and chain tensioner.

got everything back together and when I started in maintenance mode I had the check hybrid system message, but no misfire. Overall the car idle very nicely…. I bleed the coolant system and proceeded to use the vehicle to see if a drive cycle would clear the warning message on the dash.

while it was in the driveway I noticed a puddle of oil and found the new tensioner was leaking, replaced and then that’s when I had the fumble mentioned in my previous post

 

So I swapped ignition coils, and cylinder 2 is still miss firing, I will change the spark plug tomorrow and swap injectors after…. Could it be the harness from peeling it back three times in the last month?