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engine gasping for air after egr cleaning

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by nillyaway, Jan 29, 2021.

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  1. nillyaway

    nillyaway Junior Member

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    My 2012 prius has 158k miles and it was running fine but I decided to take apart my EGR to clean it after reading all the issues with blown gasket on this board. After I cleaned it I reinstalled it and turned on engine and it started shaking and sounds like it was gasping for air. I've had experiences of engine knocking before but I believe it was because of not being used for 10 days and all the moistures in the engine compartment. This time its not quite the same because my engine sounded like a wounded animal on its last breath. There were no lights on the dashboard so it was not throwing any error incase I didn't connect any of the electrical sensors. There are 3 things that I think could have contributed to this issue.
    1. The EGR cooler was was not completely dry when I reinstalled it.
    2. Leftover chemicals from cleaning egr valve. When I cleaned the valve I used engine degreaser (the foam type). Afterward I whipped it up with some paper towl and did not rinse the residue of this degreaser foam. I didn't want to use water in it because the valve has the electronic component attached to it. The reason why I mention this is because when I turned it on the exhaust smelled funky as if it was burning that chemical residue left inside the valve.
    3. Perhaps I did not installed the valve correctly and the valve was not opening correctly. I just screwed the 2 philips screws back on as tight as I could with my hand so I not sure what else I could have done wrong with this process. I remember reading somewhere that the magnet has to be torque in a specific way and I'm still not sure what they were talking about.

    If anyone has gone through this and can comment then I will greatly appreciate it. If anyone consider doing this I would suggest just selling the car if you don't want to go through this hassle. My egr had a lot of clogged up carbon build up so honestly its just a ticking time bomb thats waiting to happen.
     
    #1 nillyaway, Jan 29, 2021
  2. nillyaway

    nillyaway Junior Member

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    I just want to add a 4th possible cause is that I spilled a little coolant when I took off the hoses. It wasn't much but I'm wondering if this cause air bubbles. If I didn't get any warning lights on my dashboard then I guess it there were no error detected I hope.
     
    #2 nillyaway, Jan 29, 2021
  3. bisco

    bisco cookie crumbler

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    bump

    all the best!
     
    #3 bisco, Jan 29, 2021
  4. ChapmanF

    ChapmanF Senior Member

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    Intake leak is a possibility. You disturb a bunch of intake connections in this process, some have gaskets. The connections are all downstream of the mass airflow sensor, so any air that gets sucked in is 'unmetered' and the ECM does not know to correct the fuel/air ratio. Ghastly misfiring results.

    Just throwing that on the heap of things to investigate, as it's a known likely suspect.

    As for the EGR valve not opening correctly, if this racket is happening at idle, there should be no EGR then. It might be more on point to wonder if the valve is closing completely.

    It's easy to make the valve reassembly sound more complicated than it is. You spin the rotor down on the threads of the shaft as far as you can and hold it there. You try to hold it there as long as you can while you put the stator/cover back on, but you have to let go eventually because you're not leaving your finger in there for good, and the spring under the rotor probably pushes it back up some.

    That means as you push the stator/cover the rest of the way on and tighten the screws, probably the valve pintle got pushed a little bit open, meaning the valve isn't completely closed. That's no big deal, in fact it is a favor, because it gives you the chance to push the pintle back in with your thumb, making sure it moves smoothly. (You will hear/feel a little whirr from inside, because pushing the pintle in makes the rotor have to spin.)

    That's not something you have to do, but it gives you a chance to find out if you got something cockeyed and it's somehow jammed and won't move.

    As long as it's not jammed and it can move, it doesn't really matter whether it's open or not when you put it back on the car, because the first thing the ECM will say when you start up the car will be "hmm, closed, where is closed? ... spin spin spin ... ah, yes, there it is."

    Edit: I should probably clarify that: the valve doesn't have a position sensor. So the ECM can't actually find "closed" and confirm it is there. But it knows the valve is capable of moving about 110 steps from full closed to full open. So the ECM just sends it 110 or more step commands in the 'close' direction, then says "there, I'm pretty sure it's closed now." And it will be right, of course, unless something is cockeyed and jammed and won't move.
     
    #4 ChapmanF, Jan 29, 2021
    Last edited: Jan 29, 2021
  5. nillyaway

    nillyaway Junior Member

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    This afternoon I disassemble the pipe leading to the valve and saw some moisture in there. I then turned it on and put it on maintenance mode and let it run. At first it made the same heaving sounds it did last night but this time it was less dramatic than before. This gave me a little hope that its just burning residue. There were quite a bit of white smoke coming from the exhaust. I kind just let it run for 15 minutes and it slowly got better. I guess it was burning any moisture residue and left over cleaning chemicals. I appreciate the detailed response ChapmanF.
     
    #5 nillyaway, Jan 29, 2021
  6. Rebound

    Rebound Senior Member

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    I did this procedure with a friend and we had a VERY rough startup. Then we restarted and it was fine and the car’s running great.

    If that doesn’t do it, check the electrical connectors, like the MAP, MAF and the throttle body connector. Be sure they’re clicked completely into place.
     
    #6 Rebound, Jan 29, 2021
  7. tankyuong

    tankyuong Senior Member

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    It has to go through a cycle of roughness after a cleaning
     
    #7 tankyuong, Jan 29, 2021
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Did you remove and thoroughly clean the intake manifold? It has Exhaust Gas Recirculation passages, small ones at each port, which are particularly clog-prone.
     
    #8 Mendel Leisk, Jan 29, 2021
    Last edited: Jan 29, 2021
  9. nillyaway

    nillyaway Junior Member

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    I have not since it took me so long to finish with the valve and cooler cleaning. I only scraped out a little bit where the pipe mate with the manifold opening. The engine is back to normal so I have had enough of car care for another couple of months.
     
    #9 nillyaway, Jan 30, 2021
    icyrius and Mendel Leisk like this.
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