Rough startup when cold, P0300-P0303 codes

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by LazuliNyx, Jan 18, 2025.

  1. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Not the same thing. It's an attempted same thing.

    There's a reason Aisin is required to grind Toyota's name off of a certain percentage of what they produce. I can't tell you what specific test they are failing, but I wouldn't easily trust one in a car that already had a reputation for poor thermal management and head gasket failures.
     
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  2. Mendel Leisk

    Mendel Leisk Senior Member

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    I’m game to try the Aisin badged, if and when. Will buy from so far reliable source, and hang on to the original.
     
  3. rjparker

    rjparker Tu Humilde Sirviente

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    I would not do the oil pan gasket unless it was leaking.

    The usual oil leaks are at the timing chain cover and the timing chain tensioner. Sometimes the oil pressure switch blows out and leaks. The timing chain cover is particularly tricky at the block seams when doing it in the car like you are.
     
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  4. LazuliNyx

    LazuliNyx Junior Member

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    Thanks, that's good to know. I'll inspect the pan for leaks instead, and only do it if leaking. Any tips for doing the timing chain cover FIPG? The timing chain kit I got includes a new tensioner and gasket, so should be good there once I torque it on properly.
     
  5. rjparker

    rjparker Tu Humilde Sirviente

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    Read and follow the repair manual. Understand why it says use extra form in place gasket at seams.

    You are unlikely to do it in the short time frame they recommend especially when it comes to doing things like temporary installation of the engine mount and oil filter housing to ensure the sealant is compressed while setting.

    Which is why some use slow setting sealants and hope for the best.
     

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    #45 rjparker, Jan 28, 2025
    Last edited: Jan 28, 2025
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Watch Gasket Masters hands-on technique, it's funky but effective. Not sure if they mention, but you want to also put a bead on the engine seams (A, B and C in @rjparker's images above). Using a slower curing gasket-in-a-tube affords (such as Permatex Ultra-Black) affords you a much more leasurely working time. The linked video below should start just at the commence of applying the goop:



    You should maybe use a little more attention to detail, avoiding sealant in bolt holes, gaps in the coverage, but the idea is sound.
     
  7. LazuliNyx

    LazuliNyx Junior Member

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    I have the head, cam housing, and timing chain and cover on now. I followed the manual and of course watched the video on the sealant for the timing chain cover. It's definitely much easier when using a 24 hour sealant since you don't have to finish torquing in 15 minutes. I need to go to the dealer for a couple of valve cover gaskets that didn't come with the felpro head gasket kit I bought, as well as some radiator hoses I decided to replace. Maybe I'll be able to crank her up by this weekend.

    Regarding the oil pan, I appreciate RJParker's input. It's possible it might be seeping a tiny bit but doesn't look like anything that will drip. It can definitely wait, and I looked at the procedure and saw the removal is difficult due to prying off with the old sealant in place. I did want to see what the oil at the bottom of the pan looked like. I had removed the dipstick tube, so I stick the dipstick into the hole until I felt bottom. Does this reach the bottom of the pan? The oil looked clean (I had changed it 1000 miles ago, and nothing sludge like was on the tip where it touched metal. I've done pretty well at changing the oil and filter, and It looks like the previous owner did too. In fact they took care of the car pretty well it seems, except of course not doing the things Toyota doesn't tell us about like the EGR system clean.
     

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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    I think Toyota's gasket kit is much better. With FelPro, apart from their accurately designed head gasket, the rest is mostly off-the-shelf, this'll-fit. The Toyota kit's about $250 USD.

    Definitely let sleeping dogs lie, with the oil pan. It can be done any time, too.
     
  9. LazuliNyx

    LazuliNyx Junior Member

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    So I got the felpro kit because of the head gasket, but there's definitely an issue with the fuel injector O-rings, when I cranked it, it started leaking and when I pulled the no 2 fuel injector I could see the o-ring was pinched. I'm going to get the OEM gaskets for the injectors.

    Of big concern is that the engine was running extremely rough and rattling. I'm not sure what to look into next to see what's happening.
     
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  10. LazuliNyx

    LazuliNyx Junior Member

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    Ok, I reset the fuel injectors into the rail and that stopped the leak. I'm gonna order the o-rings from the cheapest toyota source, and keep those on until I get those, as the pinching might have just been a mistake inserting it the first time.

    On to the misfire, I'm aware I need to check timing, ignition, and fuel injection. I'm planning to get techstream setup to help diagnose it. Are there any other systems to check? If necessary I'll look back into the cylinders to see if there's any issues with the new gasket, but I followed the manual and videos shared to the letter. For timing, I read on here that I can get cyl 1 to tdc with the valve cover and main pulley off and peek at the crank chain position and compare to the position on the cams. For techstream, is there any quickstart guide on diagnosing misfires?
     
  11. LazuliNyx

    LazuliNyx Junior Member

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    IMG_2435.jpeg IMG_2436.jpeg IMG_2432.jpeg Ok so I pulled the injectors and found the black tips missing on two of them. A third broke off when I gently touched it so the plastic must have gotten brittle. I don’t see any of the tips in the cylinder head ports nor in the cylinders so I’m assuming they broke off earlier and I didn’t see it when reinstalling. Besides that, I checked the timing marks on the chain and sprockets and I think they look good. The two cam markers line up and the yellow crank marker lines up to the dot visible through the timing cover. IMG_2435.jpeg
     
  12. CR94

    CR94 Senior Member

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    Of course not all did, but it was commonplace for 1950s engines to go well over twice that far, given reasonable treatment. I know of several that did.

    In over 900k miles of car ownership, I've had to replace exactly one master cylinder. Doing that ten times would be a heck of a lot easier and cheaper than replacing a Prius's unreliable booster contraption once.
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    @LazuliNyx excuse my ignorance, but is it mandatory for the injectors to come off with head removal? Could the fuel rail be disconnected from fuel line, but other’n that everything left in place?

    I can appreciate there’s reasons to completely remove the injectors nevertheless, say for cleaning/inspection, or if you’re handing the head over to machine shop for refurbishment.

    I’ve read it can be tough to reseat the injectors, the o-rings are problematic and so on.

    On the other hand, maybe good to do, especially if you have replacement o-rings on hand (say with the gasket kit).
     
    #53 Mendel Leisk, Feb 6, 2025 at 8:20 AM
    Last edited: Feb 6, 2025 at 8:26 AM
  14. ChapmanF

    ChapmanF Senior Member

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    I believe the O rings usually at risk of getting pinched are those between the injector and the fuel rail, so leaving the injectors in the head wouldn't eliminate the need to be careful reinserting the ends in the fuel rail. The bottom ends sit in the head in much more trouble-free grommets.

    The pinching can be an issue whether they're Toyota's or somebody else's O rings. More a matter of technique:

    [​IMG]
    [​IMG]
     
  15. LazuliNyx

    LazuliNyx Junior Member

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    This. I could have left the injectors and rail on the head but I didn’t feel comfortable leaving them in when taking it to get machined and working on the valves and steam seals. Those things leak like hell if you don’t get them in right or worse the o-ring will shred.

    in other news, Curie, (my gen 3 is named after a shuttlecraft on Star Trek TNG), is back up and running. On to 250K miles. And EGR cleaning every 30k? And emptying the oil catch can every oil change.