Gen4 to Gen3 engine swap using gen 4 intake and egr, DONE!

Discussion in 'Gen 3 Prius Technical Discussion' started by Dave Hanson, Aug 13, 2019.

  1. Dave Hanson

    Dave Hanson Member

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    Gen 4 throttle body should be just fine, my new engine didn't come with it, so I used my old one. I didn't remove water pump or intake to install and didn't have any clearance problems. Did leave exhaust manifold off the engine but connected to the the rest of the exhaust system, for windshield clearance. Good luck.
     
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  2. Alexander D

    Alexander D Junior Member

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    New to Priuschat here and working on doing this swap on my girlfriends 2014 Plug in with 94k on it. No idea why, but she was driving it, heard a pop, and now there's a hole in the engine block.
    Already got the old engine out took about 4-5 hours removed it with the exhaust manifold attached, water pump removed and had no clearance issues with the windshield.
    Currently prepping the new engine to go in, planning on using the gen 4 intake, throttle body, and egr. Using the gen 3 exhaust manifold, flywheel/damper, and wiring harness.

    All the wires line up pretty much the same except for a sensor at the very bottom of the gen 4 engine by the ac compressor that isn't on the gen 3 (Pic1), and the two different map sensors. I assumed the sensor by the ac compressor was unneccesary, and was going to simply not plug it in, no worries. However If I am understanding correctly, the gen 4 map sensor is located by the top left of the intake and has 3 wires and a small tube coming out of it and going to the intake (pic2), while the gen 3 map sensor is built into the intake manifold and has 4 wires and a larger opening (pic3).

    Will using the gen 3 map sensor and simply running a tube from it to somewhere on the gen 4 intake work?

    pic1.jpg pic2.jpg pic3.jpg
     
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  3. Dave Hanson

    Dave Hanson Member

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    I'm pretty sure that long of a hose wouldn't give a real time MAP reading. That's why I just spliced in the new sensor wires into my old harness, and I made sure the hose between the sensor and manifold was as short as possible(even shorter than where I had originally placed it). Hope this helps, Dave.
     
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  4. cnc97

    cnc97 Senior Member

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    And the sensor near the AC comp mounting is an oil level sensor. Not used on the Gen 3. I wonder if Toyo added it because of the oil burning issues, or the likelihood of Gen 3 owners to NOT check the oil.
     
  5. tvpierce

    tvpierce Senior Member

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    That's interesting.
     
  6. Alexander D

    Alexander D Junior Member

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    Today the CEL turned on for a p0401, EGR Flow insufficient detected in my gen 4 to gen 3 swap. I'm going to take off the windshield wiper tray in a couple days and get a closer look but I'm wondering what would cause that in relation to the swap.
    Possibly an exhaust leak at the EGR tube to EGR gasket? Maybe the bending of the EGR Exhaust tube caused a reduction in flow? Or maybe the EGR is not getting enough coolant run over it, because the engine coolant was low at the time as well.
    Any opinions/guesses as to the cause?
     
  7. ACC23

    ACC23 New Member

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    hey guys is there a picture of the new hose routing, thank you for the diagram, but im still not getting.. i have the gen4 engine , i bent the exhaust manifold to match with the gen4 egr .. im using the gen3 intake
    thanks guys!!
     
    #47 ACC23, Mar 6, 2020
    Last edited: Mar 7, 2020
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I don't claim to understand, but I put this together:
     

    Attached Files:

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  9. ACC23

    ACC23 New Member

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    Part 12 of Fixthatprius! video will answer most of my question. My car isnt a V so i'll see how much if anything is different . i know its going to a bit different since im using a 4gen EGR

     
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  10. ACC23

    ACC23 New Member

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    ITS ALIVVVVVVVE!!!

    Thanks to everyones on priuschat !
    I have one concern though , this engine seems to be much louder and seems to have like a ticking noise.
    I don't know if maybe I just got a worn engine or I've read a couple post saying that the Gen4 is quite loud.
    what is your guys experience ?
     
    #50 ACC23, Mar 11, 2020
    Last edited: Mar 11, 2020
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  11. Dave Hanson

    Dave Hanson Member

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    One louder than the other, I can't tell you. My hearing is very bad. But your sound may be an exhaust leak between egr cooler and the exhaust manifold. I'd check it out with a piece of paper taped to the end of a stick.
     
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  12. Alexander D

    Alexander D Junior Member

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    I would second the exhaust leak, check the flange that connects the exhaust manifold to the rest of the exhaust as well. Feeling around there with a piece of paper or even your hand should work fine. If there is a leak between the egr cooler and the exhaust manifold you may get a CEL for the EGR insufficient flow.
    I haven't noticed one being any louder than the other.
     
  13. ACC23

    ACC23 New Member

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    I don't think its a an exhaust leak, i know that normally exhaust leak sounds like a lawmower, it. sounds like a valve ticking. ill double check for an exhaust leak though, thanks all
     
  14. ACC23

    ACC23 New Member

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    when I picked up the engine from lkq it did have some surface rust on some of the bolts, like it had been left out in the rain or something , which was super concerning, but it runs fine......so far!ha
     
  15. Dave Hanson

    Dave Hanson Member

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    Update, don't make this change, ultimately doesn't help.
     
  16. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah someone else concurs, @RightOnTime IIRC.

    And there were reports that trying to make fourth gen EGR work with third (involving heating/bending the 3rd gen exhaust-to-EGR connection pipe) resulted in driveability problems; the fourth gen EGR has different operating parameters, and third gen ECU doesn't work with it optimally??
     
  17. ChapmanF

    ChapmanF Senior Member

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    Yeah, it turns out the change from EGR at the manifold to EGR after the cat involves more than "look, less sooty down here." Catalyzed EGR lowers the pressure, changes the temperature and chemical makeup, does different stuff in the cylinder during combustion. It's a different ball game. The third-gen ECU is calibrated for one, the fourth-gen for the other.
     
  18. Prodigyplace

    Prodigyplace Senior Member

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    I read the title and wondered why somebody woul put a Gen 3 engine in a Gen 4 Prius.
     
  19. OGyanggang2020

    OGyanggang2020 Junior Member

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    My head gasket has failed me a second time now on my 2010. 220,000 miles. New head gasket made it 30,000 miles.

    Is it worth it to put a gen 4 engine in? I found them from 895 to 1200 locally. What is the consensus on the best method?
     
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  20. ASRDogman

    ASRDogman Senior Member

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    I would like to understand why it failed at only 30,000 miles!
    Maybe the head was warped? Clogged EGR? Head bolts not torqued correctly?
    Cheap gasket???

     
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