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Gen 3 to 4 engine swap failure

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by christian cox, Apr 17, 2022.

  1. PriusCamper

    PriusCamper Senior Member

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    Yay!!! Thanks for not giving up... It was so sad to read you were going to rebuild the Gen3 and put it back in. For all of us who hope to one day do this engine swap, it's a great relief that your persistence paid off!
     
  2. christian cox

    christian cox Member

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    Found one reasonably priced on amazon with a year warranty and decent reviews.
     

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  3. christian cox

    christian cox Member

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    Well I do believe prayer and it’s always about the time when I feel like giving up that I get a blessing and things work out. Thanks for urging me not quit I appreciate the spirit. I felt like I was driven to just keep resetting the ecu (disconnecting the 12 V battery and pulling the white main wire to the fuse in the front engine bay) and just getting the engine to turn over. I’m guessing after sitting in a warehouse for who knows how long the engine may have been gummed up maybe that’s just what it needed?
     
    #23 christian cox, Apr 21, 2022
    Last edited: Apr 21, 2022
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  4. EH6TunerDaniel

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    Maybe. Did you replace the spark plugs when you swapped it in?

    Have you diagnosed the misfire yet?
     
  5. 2010moneypit?

    2010moneypit? Active Member

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    Be careful with aftermarket water pumps. They can cause lots of problems.
     
  6. EH6TunerDaniel

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    I just realized that looks like a third gen water pump you should be using a 4th gen one.
     
  7. christian cox

    christian cox Member

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    Yes It turns out the misfire was not related to the coil pack it actually was the wiring that went into the top of the fuel injector . And it was the same for cam sensor. Now I’m having an issue with a brand new water pump. The engine came with a water pump it didn’t seem to work that’s why I purchased a newer water pump now that this one doesn’t work I realize that the other one probably works because the impeller on it turns so freely just like the new one & so usually the best indicator when they break is that just freezes so I’m wondering now if it’s because its a generic brand or maybe there’s another wiring problem.
     
  8. christian cox

    christian cox Member

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    Yeah they are as I’m finding out a gamble. The one I just purchased doesn’t seem to work it just throws a code. So now I’m looking to buy another one I guess I’m gonna have to buy a really pricey OEM pump and send this one back. Or maybe it’s just another wiring issue as the misfire wasn’t a coil pack it was the fuel injection wiring as was the cam sensor issue also.
     
  9. christian cox

    christian cox Member

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    A gen 3 wiring harness & a gen 3 ecu would seem to make better sense using a gen 3 water pump. I have an idea. Why not hack the harness with thermostatic relay and just set it to the same temperature as the thermostat when it opens . You will get a code but at least you can drive and not need to worry if your cars computer is compatible with a very specific OEM water pump. I mean it like hit or miss with these generic water pumps ! And so how to connect an accurate sensor to the engine or the water hose would be the next idea ?
     
  10. christian cox

    christian cox Member

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    Do you know which pump works best for the gen 4 to gen 3 swap? The new Prius just bought just throwing codes:(
     
  11. ASRDogman

    ASRDogman Senior Member

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    You should repair the wiring FIRST to the water pump. It won't matter what pump you use
    if the wiring to it has not power, or ground. As was the case with the injector and sensor.
     
  12. 2010moneypit?

    2010moneypit? Active Member

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    I would suggest a factory water pump.
     
  13. ChapmanF

    ChapmanF Senior Member

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    If anybody would like to identify the differences, I'd be interested.

    There's information about the Gen 3 pump over here.
     
  14. PriusCamper

    PriusCamper Senior Member

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    Hope you get your money back on all the parts your bought that you didn't need!
     
  15. christian cox

    christian cox Member

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    Its getting 14 v and the ground is good as well. The other two wires I’m not sure about. But there no breaks and the wires look good all the way back to the ecu,
     
  16. christian cox

    christian cox Member

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    Do you know the model number of the factory water pump? Does it make a difference if it’s on the GEN four engine?
     
  17. christian cox

    christian cox Member

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    I did . I always order through amazon.
     
  18. 2010moneypit?

    2010moneypit? Active Member

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    sorry I don’t.
     
  19. christian cox

    christian cox Member

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    So I bought another new water pump and I’m still having the same issue not sure what the problem is I powered up the new pump directly and it works fine but just after being in the car for a few minutes I gotta check engine light and the pump doesn’t seem to be working at all any ideas anybody? I swapped a couple of the relays and that didn’t work I’ve jumped the pump from the main fuse box that did work but the pump runs at full speed all the time so not sure what to do
     
  20. EH6TunerDaniel

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    What’s the code?