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Ignition Coils - Frequent Recommendation to Replace

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by cowgurlprius, Mar 9, 2022.

  1. cowgurlprius

    cowgurlprius New Member

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    Hi! Years of lurking, first time posting.

    I have a 2014 Prius II. Put on 70k miles in my 4 years of owning. 140k now. Religious oil changes when the light comes on since owning it.

    In Dec 2020 (probably 115k miles) My engine light came on - and stuttering, shaking - immediately brought in to shop, had 4 coils and spark plugs replaced.
    Put on 8~10?k miles and in Oct 2021 the same issue happened. Brought it in and did another 4 coil replacement spark plug change.

    Did a ~8k on a cross country road trip. Lower MPG (packed Prius + Roof rack/cold winter temps)
    Different accelerating (would not say trouble or "rough riding" necessarily.
    Started using fuel injector and noticed an increase again in MPG/better accelerating.
    Dropped off my Prius at the dealership to get the transmission fluid changed.
    They're telling me my Prius is driving really rough and I need to have the spark plugs and coils replaced. I let them know I just had this done within the past 6 months and for now I will just stick with the Transmission Fluid and wait until I've done some research for the coil packs.

    Curious if anyone else has found themselves in a similar issue with the coil packs?

    Or and advice on what the issue could be. Not sure if I need to look into the battery eventually?
    My battery bars generally are above halfway if not almost always charged.

    Not sure if there are other details needed.

    Thanks!
     
  2. JC91006

    JC91006 Senior Member

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    The spark plugs and coil packs that you replaced, are they original OEM quality? Many shops will replace them with inferior parts and they would not last or would not work well.

    These cars are also known to have a clogged EGR/intake system at high mileage, that can potentially lead to a head gasket failure. So if the head gasket is not already bad, it'll be best to address the EGR/intake system cleaning too.
     
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  3. tankyuong

    tankyuong Senior Member

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    Or bad injectors
     
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  4. cowgurlprius

    cowgurlprius New Member

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    thanks for the reply. I cant answer about the coil packs unfortunately but will look into it. Thank you for the advice.

    Started by cleaning my throttle body; did find oil inside - I reset the battery by taking the negative end off for 15 seconds. Drove around and noticed the hiccup with acceleration near the middle bar was not as noticeable. Will see how it goes over this week and look into working on or bringing it somewhere for the intake manifold this weekend.

    Thanks for the tips! I appreciate it.

     
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  5. cowgurlprius

    cowgurlprius New Member

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    Colder morning, initial startup was knocking and after 10 seconds the check engine light came on.
    We cleaned the throttle body again yesterday (after a 600-800 miles drive to MA). Maybe that didn't help?
    Turned off the car and took another one to work.

    Going to rent a code reader, see what cylinders are misfiring. In the past it has been the same ones (2 coil replacements in 2020 and 2021).
    Plan to take off the throttle body and intake manifold and clean that with an overnight soak. Replace the throttle body gasket. And then from there see if I should replace some of the coils.

    Any other pointers are appreciated. I only took one year of auto tech in HS and my partner is an old school Volvo Guy, so I'm learning a lot. (y)
     
  6. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    Why did the shop do that? Did they tell you the codes involved? The codes that often come up around those miles are P0300, P0301 and P0302, which indicate misfire in cylinders 1 and 2.

    Mechanics seem to go for the low-hanging fruit option, which is to give you a full/new set of coils/plugs. Which is likely a total waste. Simplest/cheapest tactic, assuming misfire codes on cylinder 1 and/or 2, is to just move the coils/plugs around, see if the code follows.

    If the code doesn't follow, it's likely your head gasket is failing. 3rd gen head gaskets are failing with tedious regularity, anywhere between 120K and 200K miles, and typically at cylinders 1 or 2. Most often at the wall between those two.

    It's my unproven and highly speculative theory that the head gaskets are mostly failing due to carbon-clogged Exhaust Gas Recirculation system. For more info see the first link in my signature.
     
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  7. cowgurlprius

    cowgurlprius New Member

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    They did, and let me know it was P0301 and P0302. They talked me into doing all 4 cause they couldn't guarantee just replacing 2. I was too scared/lazy at the time to learn more about the problem myself and I regret it. Definitely low hanging fruit for a fix.

    Your other posts I've followed on Head Gaskets and EGR has been really useful and informative. Thank you!





     
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  8. cowgurlprius

    cowgurlprius New Member

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    Progress Update:

    Replaced PCV valve yesterday.
    Took car around the block, still louder than what I like, but the check engine light had turned off after resetting the battery. Realized that the battery was not reset after cleaning the throttle body.
    Today we tested EGR by unplugging and blocking the pipe with a plastering tool. I am fearing its a head gasket but hoping it is the EGR. We drove around the block and the shaking did not seem as bad as normal but still occurring. In my opinion when initially leaving the drive way and pulling in. Started by cleaned EGR ports in the intake manifold. Took out EGR and cleaned it.

    I feel like it was very dirty. We held it up to the sun and could not see through it. After cleaning the difference is really visible.

    Tomorrow we will put it back together. I think I still may replace the 2 coils, or switch them around. We'll see. I don't feel comfortable driving it to get the code read, and unfortunately can't find a place to rent a code reader for an hour.
    Hopeful that the EGR solves some of the issues... or at least buys me some time.
    Either way it's been a fun learning process and makes car issues less daunting. Thanks for all the input.
     

    Attached Files:

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  9. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    You really have to override autoexposure to get a decent pic of the cooler innards. Second pic’s not bad; was that with cleaning in progress?

    Again: you can’t reverse a head gasket failure by cleaning the EGR, but it is good to do.

    hope it works out.
     
  10. ChapmanF

    ChapmanF Senior Member

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    For the forum to accumulate better information on just how dirty one might be at different mileage, it is very helpful whenever a person doing an EGR cleaning job can post the car's actual EGR flow numbers just before and just after cleaning, and the car's odometer reading. Only adds a minute or two to the job.

    Naturally, it's too late after the fact to get the before numbers. But this can remind someone in the future who might be thinking of doing an EGR cleaning and sees this thread.
     
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  11. Dagoba

    Dagoba New Member

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    Highly suggest getting a bluetooth reader at the least (providing you have a smartphone). There are options available that will work in the $30-$40 range. Will pay for itself the first time you use it, and troubleshooting without one can really be flying blind. Not to mention the inconvenience of having to rent one or drive to a mechanic when you most need it - whilst simultaneously not being able to drive the car...
     
  12. cowgurlprius

    cowgurlprius New Member

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    Thank you! New to working on my car/forums and will definitely try to include more information/better pictures and EGR flow numbers.
    The only thing I can add is that my car's odometer is at 147,000k.


     
  13. cowgurlprius

    cowgurlprius New Member

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    Thank you! I just found one online that I think I will order. It will make it a lot easier than just going off the codes I was told 1 month ago.

     
  14. cowgurlprius

    cowgurlprius New Member

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    TLDR: things are better for now-ish thanks for all the advice (y)

    Updated Progress:
    Put back in the cleaned EGR today. Put everything back except the wiper assembly and drove it around the block. Was rattling and I hated even driving it. Drove to get the codes read, popped up P0102, P0113, P0302, P0403. Was bummed because originally it was just P0302.
    Looked up the codes (MAF) and realized that didn't get plugged back in my eagerness to drive it again. Whoopsies. Lesson learned.
    Plugged back in the MAF. Took the advice from Mendel and moved my coils around. Reset the battery.
    Turned the car on, drove for about 5 miles, no codes came up on the code reader.
    The driving was much better. There was an initial rattle for a couple of seconds. My rough spot between 40-50mph and right in the middle of the "power?" bar is where I get the most shakes. I was able to drive normally and there was no longer any rough driving.
    I do feel hopeful and encouraged that there wasn't roughness.

    I am a bit nervous that a) the codes might not have read because some take a bit of driving to signal a warning and b) the head gasket in the future.

    I will note that for whatever reason that possessed me; I used to drive with ECO mode on religiously every single time I drove pretty much. I've seen some posts mentioning ECO mode keeping something cooler being involved head gasket failures. I'm not a car or science person for whatever that anecdote is worth. I do regret always driving in ECO.

    Side note: cracked a bolt when putting the intake manifold back together. It is the center screw. I have attached a photo. I'm not sure really what to do, but the bottom half of it is still in there. How to go about getting this out to put another one in? Will it cause a lot of damage driving without one? The other 2 of the 3 on the left and right are fine.

    Either way, good learning experience, feel more comfortable figuring out the issues with cars.
     

    Attached Files:

  15. Dagoba

    Dagoba New Member

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    Depends. If you remove the manifold, is there any of the bolt left showing past the head? Like enough to get a pair of vice grips around? If not, you're relegated to using some flavor of bolt extractor. Ez-out is one type, but there are different flavors for different applications. It's a lot to explain the proper use of bolt extractors, but do a bit of googling on the subject.

    Essentially, if the thing snapped off so that it's fairly clean and flat, you can carefully drill into the top of the bolt with a high quality split point drill bit (do not skimp on the bit, ideally some type of cobalt steel is best). The bit is sized for the ez-out, which is a bit smaller than the bolt shaft itself. I'm sure there are youtube videos on ez-out extraction.

    Using that method takes some finesse, and it is easily possible to screw up the hole/threads.

    There are other ones that are much more fool proof, but they are expensive. This is one of those options:

    3 PIECE BUST-N-OUT KIT FOR 1/4" ZB250 | Matco Tools

    It progressively takes the sheared shaft from flat to concave so that it can accept a bolt extractor, while protecting the threaded hole that the busted bolt is in.

    If you don't have experience in this realm it's the kind of thing you'd want an experienced mechanic to do. If you bungle up the threads badly enough it means using something like a helicoil or a time-sert to repair the head. Not very fun stuff :/

    The intake manifold is a plastic molded piece, and only has to crush a rubber gasket, so it sounds like you may have really wrenched down on it to get the bolt to break? I don't know the torque spec for the manifold bolts/nuts, but it is certainly good practice to find out those values and use a torque wrench for assembly. It will really help avoid these kind of situations :)
     
  16. Mendel Leisk

    Mendel Leisk Patron saint of newly poured sidewalks

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    First link in my signature has pdf’s with all Exhaust Gas Recirculation cleaning torque values. Hopefully not installing bolts with an impact: 3/8” drive torque wrench is good for this.
     
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  17. cowgurlprius

    cowgurlprius New Member

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    UPDATE:
    Check Engine came on yesterday, Reading P0303.
    Excited to see as before I had a P0302 code and moved all my coils one over. Got 1 new coil from the dealership. After replacing P0303 in the Taco Bell parking lot (Live Mas) I drove for 30-40 miles and the check engine light went off. There has been no rough riding in start up or any point in acceleration since the coil swap.

    So, I'm glad the EGR/Throttle body has been cleaned and the coil replaced. The other coil packs were not OEM from what I can see and couldn't get the shop on the phone. Perhaps they could go out in the future, but we shall see.

    I have a 250 mile drive up to MA this weekend and if there are any issues/codes that come up I will update for others with EGR/Coil issues. Thanks again.
     
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  18. macondo100

    macondo100 Junior Member

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    How did it go with your P0303?
    I had issues like that, changed spark plugs and what not and the issue was with the fuel injectors. The injectors were rebuilt and the P0300 ... P0303 went away for 5 years; now I'm back with the light engine on and will once more replace the injectors with brand new ones. At this point I have 200K miles and debating whether I should dump money into this problem or not. I'm doing the work myself so at least I'm saving on the labor.
     
    #18 macondo100, Apr 24, 2023
    Last edited: Apr 24, 2023
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