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Advice on gen 4 engine into gen 3

Discussion in 'Gen 3 Prius Main Forum' started by robomoto, Dec 20, 2021.

  1. RightOnTime

    RightOnTime Senior Member

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    The tricky part is getting the coolant lines routed correctly. Once you figure that out, it is smooth sailing

    Finally - getting all the air bubbles out of the system is a plus which you are then rewarded with the radiator fan turning on at the set temp with no overheating issues.
     
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  2. robomoto

    robomoto Member

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    Ok, none of the pros here mentioned anything about codes upto this point. Which means, if there are codes, it's not going to be specifically from putting a gen 4 engine into a gen 3 body. Great.
     
    #22 robomoto, Dec 23, 2021
    Last edited: Dec 24, 2021
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  3. robomoto

    robomoto Member

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    Ok, just finished watching the following videos. Each mentions an "oxygen sensor reading" code that came up and went away after clearing it.

    That seems to be the only error code one can expect from this swap, which, again goes away by itself.

    The third video demonstrate that the gen 4 engine is infinitely quieter and smoother, with a gain of about 3 mpg. This is the way to go.



    (part 1 of 2)

    (part 2 of 2)
     
    #23 robomoto, Dec 24, 2021
    Last edited: Dec 24, 2021
  4. RightOnTime

    RightOnTime Senior Member

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    Ahh! We are well familiar with those Oxygen sensor codes.

    Old motor clogged up the upstream Oxygen sensor. Should have been replaced when doing the new engine swap in addition with a visual inspection of the catalytic converter honeycomb.

    As for the Videos that you posted, we were asked 1st to film an install of the conversion but declined because of a busy month. Glad he got it done with a capable Shop that is close by.
     
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  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Watch this series.
     
  6. robomoto

    robomoto Member

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    Believe me. I tried. Would take me forever to find where he talks about what I'm looking for.
     
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  7. Travis Decker

    Travis Decker Active Member

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    At my shop we put G4 engines into G3 cars. Some plumbing mods couple of other things, but I have multiple buddies that own hybrid shops across the US that are doing it.

    Replace your G3 water pumps at 120,000 thats what we feel is the root cause of head gasket failures….

    IMG_4716.jpg
     
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  8. robomoto

    robomoto Member

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    This reminds me, a few months back I hooked up my torque app and looked at the water pump readout labelled "WP run". It said it was off the whole time the car was running, but the coolant temp levels seemed to be within normal range and there was no code, so I just ignored it. I have it circled at the bottom on a screenshot of my app. Maybe this was a sign I shouldn't have ignored it. Better check my water pump when it comes off.

    upload_2021-12-23_23-0-16.jpeg
     
    #28 robomoto, Dec 24, 2021
    Last edited: Dec 24, 2021
  9. Travis Decker

    Travis Decker Active Member

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    Just replace it. You cannot see that its going to fail.

    The car commands the motor on, but has no way to know the impeller is slipping or dectached before its too late. Seen multiple times.

    In techstream we have “active test” for water pump on, maybe it made it into torque wrong.
     
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  10. robomoto

    robomoto Member

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    The garage with the gen 4 engine sent me pics of their engine posted below. I didn't expect the transmission to be included, but it is, and the whole thing looks to be in pretty rough shape. It's missing a coil and there's quite a bit of rust already on this newer engine. I'm guessing the earlier estimate assumes both the newer engine and tranny to be swapped in together, so the question is:

    1. Will the gen 4 tranny fit into the gen 3 chassis?
    2. Is it worth putting in this newer tranny if it does fit?
    3. Should I even use this engine given its condition?

    upload_2021-12-24_8-37-17.jpeg upload_2021-12-24_8-37-17.jpeg upload_2021-12-24_8-37-17.jpeg upload_2021-12-24_8-37-17.jpeg upload_2021-12-24_8-37-17.jpeg upload_2021-12-24_8-37-17.jpeg
     
    #30 robomoto, Dec 24, 2021
    Last edited: Dec 24, 2021
  11. meeder

    meeder Active Member

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    The waterpump is also missing.
     
  12. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    With the advertised miles it would be dubious value anyway.

    Better check with them first, if the transaxle is included. Pretty sure it would be more labour: if you just swap engines only one engine mount is involved, whereas with the transaxle there's at least a couple more.

    Fourth gen into third, you will need to swap over some bits at the interface between engine and transaxle.

    For more details: make some popcorn and watch @Ragingfit 's saga. Take notes, screen shots, as you go.
     
    #32 Mendel Leisk, Dec 24, 2021
    Last edited: Dec 24, 2021
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  13. rjparker

    rjparker Tu Humilde Sirviente

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    I doubt a gen3 hybrid system would properly operate a redesigned gen4 transaxle. Even if it would connect to the axles which it may not.

    41AD3B26-CB2B-46A9-98C9-7EA9D4588AA8.jpeg
     
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  14. robomoto

    robomoto Member

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    As expected, the tranny is not included in the job. The good new is, there was a discussion about the pictured AC compressor possibly being swapped in together if it fits. Anyone know if it does?

    This is a great shop that deals with lots of Prius taxis and other alternative fuel vehicles. Spoke with Dave the owner and he said it can be done even before the new year. They are called Alternative Fuel Solutions Automotive, in Burnaby BC. They specialize in propane conversions, engine repairs, and fleet services. They also work with a ton of Prius vehicles owned by taxi and Uber drivers. So if you have a Prius in the greater Vancouver area and need any work done including an engine replacement on a gen 3 using a gen 4 engine, this place will be your best bet. They had a gen 4 engine available for my swap, which is awesome. I will post updates as they arrive.
     
    #34 robomoto, Dec 27, 2021
    Last edited: Dec 27, 2021
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  15. robomoto

    robomoto Member

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    Shop sent me a pic of my AC compressor which was destroyed by the thrown rod. Luckily, they had a compressor from another 3rd gen laying around, so they put that in. What a win.

    They told me the car was ready at about 2pm today, which is a phenomenal turnaround time that totally surpassed my expectations. Stay tuned for more updates.


    upload_2021-12-28_15-24-12.jpeg
     
    #35 robomoto, Dec 28, 2021
    Last edited: Dec 28, 2021
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  16. robomoto

    robomoto Member

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    Got word it was done later last Tuesday. Picked it up the day after. Engine idled way quieter, and everything was as expected except there was a certain misfire-like hesitation at low RPM accelerations.

    The problem was, I told the shop they can use the gen 3 EGR, but they actually kept the gen 4 EGR by bending pipes to retrofit the gen 3 intake and exhaust, which was a bonus for me, but they forgot to re-pin the connector for the newer EGR according to this thread. That's why there was a bit of misfire going on.
    upload_2021-12-30_16-37-8.jpeg



    So I re-pinned the connector myself and the problem went away immediately. (If you DIY, make sure you watch this and do it right).


    A bit of surface rust on the engine, but can't feel it performance wise. Vastly superior engine, good shop (AFS Automotive in Burnaby, BC), standing by their workmanship. Overall, a win for my situation.


    upload_2021-12-30_16-43-42.jpeg

    upload_2021-12-30_16-44-26.jpeg


    On top of all that, I also got my AC recharged (y)
     
    #36 robomoto, Dec 30, 2021
    Last edited: Dec 30, 2021
  17. ChapmanF

    ChapmanF Senior Member

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    That re-pinning advice has gone past its sell-by date. We looked more deeply into it over in this thread here.

    The idea about re-pinning seemed to have started with @Sandog53 back in August of 2019, who didn't say anything (other than "tested the wires with a multimeter") about where the idea even came from that the pinouts changed. They didn't. We confirmed the Gen 3 and Gen 4 valve pinouts are the same, here, here, and here.

    The effect of the repinning is nothing more than to make the valve incapable of moving. Swapping those two wires puts the four stepper motor coils into an arrangement where each pair alternates between not pulling at all, and pulling both directions at once.

    So if you had some misfiring and it went away after your "re-pinning", that just means it was misfiring when it had EGR, and now hasn't got any EGR and is running more smoothly.

    The reason there is that the whole EGR system from Gen 4 is oversized for a Gen 3 exhaust. Gen 4 moved the EGR source further down the exhaust, past the catalytic converter, where the pressure is lower. The EGR components are all upsized in Gen 4 in order to flow adequate EGR at the lower pressure. When you put those larger-bore components on a Gen 3 exhaust with the higher pressure before the cat, the flow is too high.

    So far, I've yet to see a post about a fully satisfactory setup with the Gen 4 EGR components on the higher-pressure Gen 3 exhaust. Obvious ideas are to add some sort of restriction and hope it reduces flow by the right amount, but "the right amount" might not follow the curve of a simple restriction. I've seen various threads with people trying different ideas, but I don't think I've seen one yet that ended with "and now I'm happy how the engine runs."
     
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  18. robomoto

    robomoto Member

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    Ok according to this I now have a vestigial EGR valve and no actual EGR going into my engine. How will this affect the longevity of this engine? I guess with no EGR the engine will run hotter, but just how much of a cooling effect doe EGR have? I guess I can monitor my coolant temperatures using my torque app and see how it matches up to others running the same engine with a working EGR?
     
  19. Elektroingenieur

    Elektroingenieur Senior Member

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    For my part, I’d still like to hear about anyone in California who has done this exchange, taken the car to a BAR Smog Check Referee for the required inspection, and had it pass.
     
  20. robomoto

    robomoto Member

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    I'd like to hear as well.

    When I first unplugged the EGR valve connector to see if the car drove better without it, it did, but gave me a CEL right away. After re-pinning the wires and clearing the "EGR valve disconnected" fault code, the car drove well just like when it was disconnected, but there was no CEL.

    I'm just guessing but wouldn't the ECU be able to make some air-fuel adjustments via the oxygen sensors (which would now sense more oxygen due to the EGR delete) to somewhat compensate for the lack of EGR?

    It would also be useful to find out if other parts of the engine or vehicle are set up to detect a lack of EGR and throw a code in response to it.