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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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    My 2010 prius blew a head gasket @ 255,000 miles. So with the inspiration of Rafit and cnc97, I decided to swap in a generation 4 engine. I found one with 94,000 miles for $450 shipped on Hollanderparts(Car-part is another good site), half of what they wanted locally, me picking up not dropped off right under my hoist. New engine came with wiring, egr system, intake and exhaust manifolds but no throttle body(I reused my old one spinning it 180°). I wanted to use as much of the new parts as possible but knew the exhaust manifold was a no go without the downstream exhaust and at another $450 was out of the budget. So, I set out to see if my old exhaust manifold would work with the new egr system. Bolting it up, the old egr pipe on the exhaust manifold was the correct length but to low and bolt holes were twisted clockwise. After much deliberation, I took the plunge and heated the pipe up cherry red with a torch, first at the bottom to raise it most of the way, then in the middle to twist the flange and raise it into the final position. I was surprised that it went so well. Pipe post heating is in first picture. Using new intake involved: changing manifold absolute pressure (map) sensor wire connector and moving it down out of the way of the old air horn(also had to cut off its old mount)pic #2, pic #3 shows shortened intake pipe 1/2" and trimmed webbing to lower air cleaner box back down ware it belongs. Rest of pics show minor changes, mostly to wiring harness and finished product. IMG_20190809_070734.jpg IMG_20190809_070734.jpg IMG_20190809_070734.jpg IMG_20190809_073511.jpg IMG_20190809_071249.jpg IMG_20190809_071112.jpg IMG_20190809_073554.jpg IMG_20190813_084301.jpg
     

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  2. RMB

    RMB Senior Member

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    Did you open up the EGR system (cooler, pipe, and valve) to see how much buildup it has from your Gen 4 engine?
     
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  3. Dave Hanson

    Dave Hanson Member

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    Yes and it was pretty clean inside,just a light carbon coating, which brake cleaner easily took care of. I wish I would have taken pictures, but I was preoccupied with getting it to work.
     
    #3 Dave Hanson, Aug 13, 2019
    Last edited: Aug 13, 2019
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  4. Raytheeagle

    Raytheeagle Senior Member

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    +1:).

    Well done BTW(y).

    I’d be curious at 94k miles what it looks like;).

    Any info or pics are appreciated (y).
     
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  5. RMB

    RMB Senior Member

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    Ray, is there any previous data in comparison to this case? 94k and with light carbon coating on Gen4 EGR here.
     
  6. Raytheeagle

    Raytheeagle Senior Member

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    Not that I’ve seen:cool:.

    I was trying to get @soldierguy to commit locally, but they traded it in for a VW:(.

    But I’d like to see some data rolling in (y).
     
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  7. Dave Hanson

    Dave Hanson Member

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    Update, fixed a drivability problem with the help of Sandog58, who happens to be doing the exact same swap. Had to swap the red and purple wires going to the egr. Why Toyota did this is baffling and it's truly amazing that Sandog58 figured it out. Here is a picture of the plug before the red and purple wires were swaped. IMG_20190826_155322.jpg
     
  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    How'd I miss this thread???

    The exhaust manifold branch to the EGR doesn't look like anything happened to it, very slick. (y)

    The increasingly complete swaps have me thinking of a quote from The Endless Summer, for some reason:

    “The Australians are very competitive surfers- they always like to do one better than the ‘Yanks,’ as they call us. So if you go out and hang five, they’ll go out and hang 10. If you hang 10, they’ll do one better- which is something like hang body.”

    I'd like to be a fly-on-the-wall, when a Toyota service department pops the hood on one of these...
     
    #8 Mendel Leisk, Aug 27, 2019
    Last edited: Aug 27, 2019
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  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Here's the two gen's EGR troubleshooint info.There's pictures of the plugs in each.
     

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  10. Peter123

    Peter123 Active Member

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    Does this car have more power now with the replacement gen 4 engine?
     
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  11. Dave Hanson

    Dave Hanson Member

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    Really don't notice any changes in power, the electric motor provides most of the torque for acceleration, anyway. Just runs much smoother than the old one, now that I got the egr wiring straightened out. Also, still running the old 255,000 mile catalytic converter so that's not helping things. Have driven less than 300 miles since the swap but my gas mileage still seems also to be the same at about 45. If I can sell my old cleaned egr system and intake(both available in the private sale category), I probably will buy a gen4 catalytic converter and do the entire gen4 swap. On a side note, I did take apart my old engine and aside from the slime from the blown head gasket, it was in remarkably good shape. Rings were all free, still crosshatching on cylinders, bearings all looked good and that's after driving it 25 miles home, with my wife and daughter. It was missing badly and the temperature light was no most of the way but we made it. Didn't think it was worth fixing after that and wanted to see how far I could take the gen4 swap anyway.
     
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  12. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    @Dave Hanson : could you do a bullet-point list of the mods to accomodate the 4th gen engine with EGR. If it's not too nuts. Items I can think of:

    1. Heat/bend EGR connection pipe on 3rd gen exhaust manifold, to suit 4th gen EGR.
    2. Swap red and blue wires on EGR valve connector.
    3. Cut back 3rd gen engine air intake snorkel to fit 4th gen air filter box.

    Hopefully I've got the above right.
     
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  13. tvpierce

    tvpierce Senior Member

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    @Dave Hanson Thanks for documenting this. I'll continue to follow as you update.
     
  14. Dave Hanson

    Dave Hanson Member

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    I'll try to pop the hood and get a comprehensive list of all the modifications I made. Off the top of my head.
    1. Add ; Do this before installing engine, not like I did.
    2. Swap red and PURPLE wires on EGR valve connector.
    3. Good
    4. Add 3/4 pex tee in water line to accommodate lose of connection on new egr cooler. Routing I used, I will have to check out, Sandog58 would have the routing as Toyota did it on gen4, my tee is in a different place. I did this for faster heater core warm-up.
    5. Add L bracket on valve cover bolt so you have 2 supports on air box. You loose the one on the intake manifold.
    6. Move and change wiring pug for MAP sensor, wires are old yellow to purple, gray to blue and black to black. Cutoff old mount on intake manifold, it interferes with the air horn.
    7. Drill out ground connectors and bolt one to passenger and one to drivers side of head.
    8. Remove mount, saving water hose connector, of vacuum switch going to gas tank. It moves toward the passenger side to make room for the top air box mount.
    9. Miscellaneous wiring harness changes for slight sensor moves and for new lower radiator hose route. I used the new wire loomes on the top of the engine with the old wires because I thought that they gave it a more finished look.
     
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  15. Grit

    Grit Senior Member

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    Gen 4 has 121 horsepower, you’ll have to do the math.
     
  16. DaYooper

    DaYooper Member

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    Curious about this. I too did the Gen 4 swap but I have been runnIng into problems with low power. I cleaned the cats but still problems. Will have to try this next. Interested in the hose routing. Could you upload a diagram?
     
    #16 DaYooper, Sep 1, 2019
    Last edited: Sep 1, 2019
  17. Dave Hanson

    Dave Hanson Member

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    This is how I connected my hoses, with gen4 egr cooler. What gen4 parts are you using? IMG_20190901_083319.jpg
     
    #17 Dave Hanson, Sep 1, 2019
    Last edited: Sep 1, 2019
  18. ChapmanF

    ChapmanF Senior Member

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    I'd still love to see whether the Gen 4, post-cat EGR pipe can be used, and clear whatever it needs to clear in a Gen 3 ... or maybe be bent to do so, using the same technique.
     
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  19. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    What's the second word, in "temp ? bleeder"? Can't quite make it out.

    This is GOLD, btw. Thank you!
     
  20. Dave Hanson

    Dave Hanson Member

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    Excuse my poor penmanship, should be temp. sensor/ bleeder. Of course, Toyota got rid of the bleeder on post 2010s.
     
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