2012 Prius - CEL P0301 Cylinder 1 misfire/Engine knocking - FIXED

Great points, GearHead. Isn't there a rear main seal on the crankshaft between engine and trans? It would be wise to replace that as well - same story. They're usually easy to replace with the engine removed and a very cheap part.

 

@GearHead600 there's a loose plastic piece at the junction between engine and transaxle; you can see it when doing oil changes. I've never tried to pry it off, but I seem to recall you saying it's for inspection of the damper; at least it allows this? Maybe nowhere near conclusive though, compared to full disassemble?

 

I know and remember there was a viewing window for the flywheel, as my shop showed me what he thought was a crack in mine. I do not know if there is any way to view the damper without tearing things apart. I will have to investigate now!

But if that is the "window" you're referring to, you wouldn't be able to see the damper from it at all, because the window is on the 'backside' of the flywheel (no way to see the damper at all from that side)... The ONLY way you MAY be able to pull that off would be with some kind of tiny snake camera, if you could somehow snake it in the little window, to the other side of the flywheel!

Unless there is another "window" to the other side somewhere else, I'd have to investigate that now!

And as small as any "viewing window" is, at least you can manually rotate the crank to see all 360 degrees (of whatever amount of space it does show)...

 

I was thinking too: if a spring in the damper failed, maybe it (or pieces of it) would end up down by that inspection window.

 

Yeah I recently got p0012 something like “over retarded cam shaft sensor?”. Y’all reckon that’s pointing to the damper?
I suspect the head gasket because
A) the egr cooler was 100% clogged
B) car runs great until several miles in EV mode and the engine cools down
Of course I want this car to last as long as possible. And, of course I don’t want to spend any money on it.
This car was the best. I have a 2nd, 3rd, and 4th gen Prius and the 2012 plug in basically made me money. We were spending $400/mo in tolls on our commute pre plug in, versus a $280/mo car payment and FREE TOLLS! Those were the days, eh? I bought the car for $16k with 91k miles on it in 2015. It was driven 7 days a week, 160 miles round trip from the day I bought it until the HOV sticker and free tolls expired. Barely had time to do an oil change every 10k miles.
At about 230k miles I noticed a minor “roughness”... so at 236k I changed the plugs. The tank prior to my first p0301 I averaged 75mpg over 600 miles.
since I cleaned the egr circuit, new pcv, and clean intake manifold, I haven’t been plugging it in. I’m averaging 47mpg over 200 miles, with no issues until I drove down from the mountains which charged up 9 miles of EV. When the ICE switched back on, I got the knocks and the CEL.
I need to drive this car until the end of 2021, when my gen 4 hov sticker expires. After that, my 16 year old daughter is getting it. She can get back and forth to school in it without the ICE even kicking in.

 

I do reckon it COULD definitely possibly be the damper, the thing you mentioned about holding the motor at high RPM's IS one of the things that you can "do" to "get rid of" the "problem" - when it's the damper. Look at the pix of my "blown" damper in my thread, and imagine if you will, an off balance ceiling fan: If you have a severely imbalanced ceiling fan that's wobbling all over the place at low/moderate speed, when does it "balance itself out" or "catch itself" or "smooth out" - during *acceleration* or higher RPM's!

That's the other reason I made my little list, who really wants to spend $$$ they don't have to on a car! Checking the head-gasket just to know is easy/cheap! At least that way you could rule that out, or in! If you've pretty much cleaned or replaced everything else on the list, the only two things left that *I could imagine it being would be either A) the head gasket (which again can be easily verified cheap or free), or B) the damper (which I would only rule in or out by process of elimination / why it's last on my list).

I'm admittedly not familiar with either the plug-in model, OR a blown H/G on a 3G Prius, however, one of the symptom/"resolution" you have posted are *definitely* possible of a blown Damper Assembly!

 

Hoping you have an idea of why it might/will fail.

Could it be from too much starting of the engine, either at speed or when taking off from a stop?

 

I would personally think the damper assembly part would be as "routine" to replace as something like brakes (rotors/pads)! Because just think about how often a Prius ICE kicks on and off! (again, IDK about plug-in models and how they differ) but, I literally TRIED to count one day, and lost track! I could only imagine how big of a number it really is, and to think that each and every time the ICE kicks on/off that little damper and those little springs have to absorb "shock" - I am amazed mine made it (presumably if the previous owner never replaced it and it was indeed OEM/original) 290,000 miles! But if you look in my thread of the pix, it was *completely blown*! Only ONE of the FOUR springs remained "in tact" and you would literally think the engine was going to FALL OUT when I drove it into the shop to have the damper done once I pretty much trouble-shot it down to that almost literally being the LAST thing it could have been (besides something wrong actually IN the transmission)...!

But yea, I think it is a part that is inevitable to wear out and require replacement at some point, the question is just "when" not "if..! Maybe most people "move on" before their car ever reaches these types of mileages though? IDK, I plan on keeping mine until it's literally not repairable, or as we like to call it where I'm from "rockin' it till the wheels fall off"..! My GFs 2011 already has 361,000 miles on it! I'm not far behind her in a 2010 @ almost 314k..! I plan on having mine until 1,000,000 miles, as long as the wheels are still on it..! & I also drive it a LOT. I often take road trips, as much as 2k one way, 4k round trips. It's my D/D (daily) AND my work car for FULL TIME uber/lyft work. So I tend to "see" at least 200 miles per DAY!

I could also only imagine, especially when I'm controlling my driving (at the pedal rather than using Cruise), how many miles off the ODO are actually not even "on the engine"! Since a few times I have tried "counting" how many times a day my ICE turns on/off, I've started wondering, "how much accumulative distance [mileage] is actually not even 'on' the engine / on the EV only" !?!?!?!? Just the other day I did take mental note, like, "I just drove 1 mile on just EV", or "I just drove 2 miles on just EV" - "Those are THREE miles NOT 'on' the engine"! That all adds up! So when your ODO reads 361,000 miles, that does NOT mean the engine has 361,000 miles "on it"...! Lets just say, for sake of conversation, that the engine was only "on" 9/10 of the time, or 9 out of 10 miles! when the ODO reads 361,000 - the engine "only has" 324,900 miles on it! At the same time, when I drive in highly congested areas (city) for work (uber/lyft/uber eats etc), my ICE may kick ON/OFF 40 times in ONE mile!

But back to that pesky damper! Again for conversation, lets say, your motor kicks on and off 100 times (maybe a 'normal' number for a non driver / normal commuter worker? mine is WAY over 100 times a day!) per day... Most people (at least by me) work 5 days a week (*52 weeks) which comes to 260 driving days, back to that 100 ICE on/off per day, that is 26,000 times PER YEAR that your engine is turning itself ON and OFF! As where 260 driving days in a "traditional" non hybrid car, the engine is ON/OFF 520 times! (not counting ANY car that turns itself off at red lights/stops since I've noticed even non-hybrids now doing this! - and I think that's REALLY bad on their *starters* - wonder how often they're going to have to replace those!!!)

Honestly, thinking about it in that context, I'm VERY surprised they last as long as they do!

 

Question... so your damper went out... did you regularly change the trans oil / fluid?

my 2012 plug in keeps track of the EV to ice ratio, I believe for the life of the car? Maybe it’s like a trip odo where u reset it? Mine is at 93% ICE / 7% EV over 248k miles.
Good news for me, I just drove to town and the CEL is gone. P0012 is completely cleared, on its’ own. And, p0301 is just hanging around as a freeze frame. I’m still only ~200 miles post egr pcv IM open heart surgery. Anyone wanna make a prediction of if and when the CEL will return?

 

Damper is 'external' to the trans, but if you've never replaced your ATF-WS now could be the time.

Nope, but if the coolant level is lowering on the regular, it is only a matter of time before it returns.

 

I've never changed trans 'oil'. I've also only "recently" purchased the car (had something around 260k on it when I bought it). But bear in mind this car has seen like 4x - 4k-8k mile road trips, and usually about 200 miles (on avg) per day 6 days out of the week for work! (I RACK up the miles LOL)!!! I WISH my 2010 non plug in kept track of EV:ICE and/or the literal number of times the ICE has had to kick on/off too! I don't think it does... I sadly have no clue what any previous owner(s) have or have not done... At least not in the form of 'records', only any 'evidence' I see (like my local shop pointed out 'evidence' that it does look like my H/G has already been done!)

 

For your (and your pockets) sake, I hope the CEL doesn't come back on! However, I still have the urge to push you into an 'official' leakdown & compression check/test to verify the integrity of the H/G! If it's anything like it is by me, near you, it should only MAYBE run you like $60 to have a shop do this! At least then you'll know for sure whether the H/G is "good" or "not"!

 

I've *always hated* "misfire" CEL/DTCs! They're the biggest pain in the arse to diagnose on ANY (traditional) car, let alone a hybrid/prius!

 

Check for dealer related maintenance by running the VIN at : Welcome to Toyota Owners

Many dealerships will measure for hydrocarbons in the coolant, could be less costly if not as accurate.

 

good to hear of a 260k mile gen 3... I thought I was one of the highest here on PC with 248k. Over in the gen2 side, there are some crazy high miles.

but the fact that you say your HG was already done makes me feel like it’s endemic to all gen 3 Prii :-(. That plus I watched the gasket masters video RE the 2ZRE engine in a Prius and it seems as if we’re all doomed....

 

Truth, and I do not know for pure 100% fact that mine was done, but the 'evidence' my mechanic pointed out to me while my baby was on the lift did appear that it had been done prior to me owning it! "Most likely" as he said...

Bought it with about 260k, as of right now I have something near/approaching 313/314k! my GFs 2011 has 361k...!

 

FWIW the damper is dry, not in the transaxle fluid.

 

And she was the one to bring up the imbalanced ceiling fan reference, to make me "understand" and "make the leap" to just buy and replace the damper!

It made too much sense to me to not "just do it"!!! (after verifying my HG was good of course)

 

Just PM'd you a solution to possibly get you through 2021. You drive A LOT more miles than I do, but it was a long(er) term solution for me that you may want to try.

 

So here’s an update

drove down to San Berdoo on Wednesday. It’s 12 miles down hill, which charges the plug in battery 100%. I turned the EV off and ran errands in normal city traffic. No hiccups until I parked, rolled up the windows, and cranked up the AC. Once the ICe kicked on, it was knocking like crazy at initial start but then smoothed out pretty quickly. made it home ok.
went for a spin yesterday, misfired a lot. So, I tried turning the heat on high, which was tough in the summer, but it seemed to clear up the misfiring.
Today I just came back from a 15 mile drive. The heat wasn’t on, but was still “in the background”, ie it was set to heat even though the fan wasn’t on. I tried hard to recreate the misfire scenario by going hard a couple miles up hill, and then switching to ev and going several miles sans ICE. Zero misfires.
I know several people have suggested depressurizing the engine coolant as a temp / quick / cheap fix. Either by loosening the cap past the seal point, or removing the rubber gasket from the reservoir cap. Anyone currently driving like that? How many miles? My hypothesis is with the heat on some there is a little less pressure on the warped head gasket... any thoughts?
Also, with the fine coolant at the top of the threshold in the reservoir, there is a noticeable leak. But, now that it’s leaked to a lower level, it’s stabilized, and A) doesn’t leak and B) seems to have calmed considerably RE knocking.