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Need source for aftermarket ignition coils

Discussion in 'Gen 3 Prius Technical Discussion' started by Jeffery Groenke, Oct 5, 2024.

  1. Jeffery Groenke

    Jeffery Groenke New Member

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    My 2010 has been running rough and now I've got a check engine light. I put my code reader on and it says coils 1 & 2 are misfiring, so I need to replace the coils. I see lots of options on Amazon for a low price but would rather get a good part even if it costs a little more. Does anybody have a suggestion for a place to buy quality aftermarket ignition coils?

    Jeff
     
  2. Brian1954

    Brian1954 Senior Member

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    To confirm the problem is the coils, swap cylinder # 1 & 2 with # 3 & 4.
     
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  3. AzusaPrius

    AzusaPrius Senior Member

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    I got mine from Autozone for $240 plus taxes came to $258.59

    They got them for $235 right now.

    Lifetime warranty and if you ever have one that fails just go into the local Autozone and switch the bad one out right there.

    I carry the tools I need in the car for that reason, I can go anywhere and if they go bad I just find an Autozone.

    You cant go wrong and call it a day.
     
  4. AzusaPrius

    AzusaPrius Senior Member

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    That price is for all four but as sugested do the switch around to confirm its the coils.

    Otherwise if the misfires still happen on 1 and 2 you have a bad headgasket. 20241005_165655.jpeg 20241005_165814.jpeg
     
  5. ChapmanF

    ChapmanF Senior Member

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    Does that mean the codes were P0351 and P0352?

    It's always more helpful to tell us what the codes are (we can look up what they mean), and not just give some version of what they might mean and make us try to remember what codes might mean that.

    If you had the P035x codes, those are about the ignition feedback (IGF) signals the coils send back to the ECM. The codes could mean the coils are bad, but it's never a bad idea to rule out some simple issue with the wiring in the IGF circuit.
     
  6. Jeffery Groenke

    Jeffery Groenke New Member

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    Thank you for the reply, you now have me scared that it's the head gasket since it is coils 1 & 2. I didn't actually get the codes, I took it to Autozone and the report said the most likely failure is the coils. I found my OBD2 reader so I'll put my reader on it and get the codes but I won't have time to do it for a week or so.
     
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I have doubts that it is truly a coil problem... but here's what you asked for:

    rockauto.com has genuine Denso 6731310 coils for about $56 each.
    That's the best aftermarket brand for a Prius, and Rock has a reputation for selling the genuine article at the low end of market rates.

    Amazon and eBay have a serious problem with autoparts counterfeiters, particularly with electrical items. It is possible you will see the same Denso item listed on Amazon. If the price is much lower, it is probably a fake.
     
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  8. ChapmanF

    ChapmanF Senior Member

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    They read your codes and then gave you a report that didn't tell you what the codes were? Nobody needs to stand for that.
     
  9. Eddie25

    Eddie25 Active Member

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    It's highly likely you just have misfire codes and you'll be wasting money by not diagnosing it properly, which is fairly easy (swap coils like post#2, clear codes, read new codes). What are the chances two coils went bad at the same time?

    How many miles? You are right to be scared that it's a head gasket unfortunately.
     
  10. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    What’s the miles on it? If 150k or more, odds are good it’s head gasket.

    definitely try the post #2 suggestion first.
     
  11. ChapmanF

    ChapmanF Senior Member

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    That's why it sucks not having the codes in the report from Autozone. If they were P030x codes, those are just generic misfires detected, while P035x codes would be about the ignition confirmation signal from the coils.
     
  12. Jeffery Groenke

    Jeffery Groenke New Member

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    Sorry everybody I got busy at work and then went out of town for a few days, so I haven't had time to look at the Prius. It has 213K on it. I put my code reader on and got two codes: P0301 and P0302, Cylinder 1 and 2 misfire. I agree it seems very odd for the two to go at the same time. But the symptoms seem more like coil than head gasket to me. It will occasionally start up and run very rough for the first few minutes then smooth out and run normal. The roughness seems like it could be a misfire. Then it will run fine for days or even weeks before it does it again. Wouldn't a bad head gasket go bad and stay bad?
     
  13. Jeffery Groenke

    Jeffery Groenke New Member

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    By the way, how do you do a compression test on a Prius since you can't turn the engine over manually?
     
  14. Jeffery Groenke

    Jeffery Groenke New Member

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    When I read the codes I cleared them. This afternoon I needed to run a few errands and so I decided to try to drive the Prius. It ran normally and didn't throw any codes. I am not clear how a bad head gasket can cause an intermittent problem, how does that work?
     
  15. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Yes and no. It does stay bad, but it only feels bad first thing in the morning because it needed all night to leak enough coolant into the combustion chamber to create the misfire/hydrolock condition.

    It's still leaking, just not fast enough to sustain the misfire.

    You use Toyota Techstream software to tell the management computers that you want to do a compression test. It will then spin the engine without tripping the plugs or injectors.
     
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  16. ChapmanF

    ChapmanF Senior Member

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    For what it's worth, using Techstream with a Mini VCI or with a Tactric Openport 2, I've never been able to make that actually happen. Maybe it works right for people using some other dongle, like the $500 one Toyota recommends.
     
  17. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Common gen 3 head gasket failure point is the wall between cylinders one and two, towards the exhaust side.
     
  18. Jeffery Groenke

    Jeffery Groenke New Member

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    Thanks for the responses, I understand what you are saying about the overnight coolant leak. Car has 216K miles and burns oil, about a quart every 3K miles. If I choose to go down the route of fixing the head gasket then it makes sense in my mind to rebuild or replace the whole engine because the valves will be worn and the rings are bad. The car is basically in pretty decent shape, I ran the KBB and it's worth about $4,500 (with a good engine) which surprised me but it's still hard to justify the investment of what an engine rebuild would cost. I ordered NGK coils and plugs from Rock Auto for $200, I'm going to install them and see what happens. If the problem reoccurs then I will have to make the tough decision whether to scrap it or sink money into it.
     
  19. ASRDogman

    ASRDogman Senior Member

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    The valves are likely fine. But reseating them in is easy and you can do it yourself.
    1qt at every 3000 miles isn't too bad....
    216,000 isn't bad either.
    But it would be better to replace the short block than do pistons and rings. You'd have
    to check the cyclinders for scoring and out of round, which could be possible, and likely.

    A remanufactured engine from the Hybrid Pit would probably be your best best. Around $2500.00

     
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  20. rjparker

    rjparker Tu Humilde Sirviente

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    Classic early head gasket symptoms. If your coils or plugs were bad it would not clear up or be as random.

    You need a borescope test to confirm. Yes you would be better off with a rebuilt engine or at least a JDM engine you are sure is not just US salvage.

    It can get worse


    Shudder video
    “Hey Walt… they want to wait and see if it gets worse…”



    Car Care Nut HG Borescope at 7:40