Misfire misfire misfire

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Flash Roberts, Jun 18, 2025 at 7:46 PM.

  1. Flash Roberts

    Flash Roberts New Member

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    Vehicle:
    2005 Prius
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    Two
    Hey all….long time listener, first time caller. Got a 2005 with 256k miles on it. We bought it 9 yrs ago and have put about 100k miles on it. The thing has been a tank up until now. Two weeks ago I replaced plugs, coils, injectors and MAF sensor. Drove fine for a week and then got the triangle of death. Problem was an injector was leaking (totally my fault) . Replaced o ring, cleared codes and drove fine until yesterday.

    now I’m getting misfires on 2,3&4. It runs, but really rough. I’m just trying to figure out what it could be and I’m running out of ideas. I suppose one of the coils could be bad out of the box but it seems strange to me that it would drive fine. Still get 40+ mpg and then all of a sudden this. Any thoughts, ideas??
     
  2. Brian1954

    Brian1954 Senior Member

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    The replacement parts you purchased and installed a couple of weeks ago are they OEM or aftermarket, and where did you buy them from?

    Do you still have the old parts that you took out of the car?
     
    bisco likes this.
  3. Flash Roberts

    Flash Roberts New Member

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    2005 Prius
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    Actually I don’t have the old parts. The plugs were were definitely at their end, and when I pulled the coils out, two of them literally fell apart. I got the parts on Amazon which, yeah I know, but I’ve generally had no problems with parts I’ve gotten from there. I replaced both water pumps and the belts, and the exhaust whe my cat was stolen (the only things I’ve needed to replace besides brakes) with Amazon parts and zero issues.
     
  4. bisco

    bisco cookie crumbler

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    counterfeits have grown tremendously. there was a time when it didn't matter
     
  5. Brian1954

    Brian1954 Senior Member

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    I would start by replacing the spark plugs with Denso or NGK purchased at a dealership or rock auto. If that does not fix the misfires, I would buy OEM MAF sensor, then OEM injectors, and then OEM coils.