Cleaning inside cylinders via behind intake manifold

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Rocinante1984, Nov 18, 2019.

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  1. Rocinante1984

    Rocinante1984 Junior Member

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    2007 Prius, 200k Miles, P304 Code

    Hey there,

    Took off the intake manifold to try cleaning it because of a p304 misfire. It was honestly really easy getting the manifold off for this generation, however it didn't seem to need it. There was some oil pooled in there and some normal looking black gunk buildup but nothing that would really interfere with air intake.

    Got that all cleaned up but noticed there is access to each cylinder. C1 was in open position, and I used a can or two of carb cleaner inside the cylinder and blasted the gunk out with compressed air. A whole lot of gunk came out and I'm fairly confident that there isn't a pool of anything left in there. I also rotated the pistons with the spark plugs out to blast out any excess, which there wasn't much. People have done this with MMO but I think there is a whole lot more gunk in there than comes out with a soak like that.

    I have cleaned one cylinder this way, is there any reason that it can't be done for all cylinders?

    Question 1:
    Do I need to take any precautions so the cylinder doesn't have problems from lack of oil or hydrolock? Have read in some forums that people who did a soak with Marvel Mystery Oil dumped it in the top of the spark plug holes and then hit the start button with the spark plugs out to get the extra fluid out. I did rotate the cylinders to get the excess fluid out of C1 by starting it, but without any MMO. Put about a tablespoon of synthetic oil in the spark hole after cleaning that cylinder. Should I be worried about a lack of lubrication before starting the car? Just want to cover all my bases so any insight is appreciated.

    Question 2:
    How do you turn the engine by hand to get access to the other cylinders? Can't seem to find this on google.
     
    #1 Rocinante1984, Nov 18, 2019
    Last edited: Nov 18, 2019
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Regarding question 2: Taking out the plugs will make turning it easier, but either way it's not too hard. To turn it, take off front passenger wheel, pry back plastic fender liners if needed, and get a socket on an extension on the nut at the end of the crankcase. Now which direction to crank, I can never remember, maybe clockwise?? Maybe someone will know, remember.

    Taking out the plugs would give you more or less the same access?
     
    #2 Mendel Leisk, Nov 18, 2019
  3. Rocinante1984

    Rocinante1984 Junior Member

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    Well I've been doing clockwise so I hope that is correct. The valves do move. Access to the bolt was surprisingly easy once you know where to look for it.
     
    #3 Rocinante1984, Nov 18, 2019
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah I've never had the need to do this on a Toyota, but with Honda valve clearance check (screw and lock nut style, dead-easy) that was the drill.
     
    #4 Mendel Leisk, Nov 18, 2019
  5. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Clockwise is correct.
     
    #5 Georgina Rudkus, Nov 18, 2019
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  6. Rocinante1984

    Rocinante1984 Junior Member

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    Just an update months later, no change in mpg, still has p304 misfire code. As far as I can tell all the cleaning did nothing. Which makes sense I guess.
     
    #6 Rocinante1984, Feb 7, 2020
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  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. When were the iridium spark plugs last changed?
    2. Have you tried replacing the fuel injector for cylinder 4?
    3. Have you performed a cylinder compression check yet to see if the engine is in basically good condition or not?
     
    #7 Patrick Wong, Feb 8, 2020
  8. valde3

    valde3 Senior Member

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    Before anything else just swap the ignition coils around to see if the misfire changes with the coil. Swap the coils between 1 and 4 and see if you then get P0301 if you do then it's just a bad coil.

    If not and you still get the P0304 change the the plugs. Between cylinders or to new. Unless you already did this? You can do compression test at this time if you have a Techstream and compression tester.

    If still P304 and compression is good you need to start checking for wiring or injectors.

    You can just listen to the sound of injectors with a stethoscope or a long screwdriver. Do this with Prius in engine idle. To do that make sure you have a lots of hybrid battery bars. E-brake on. Push throttle to get engine running and put it in neutral. Engine will idle and hybrid battery will drain slowly so don't take too long. Turn AC off to safe hybrid battery energy. If all injectors sound the same they (and their wiring) are most likely all ok.

    To check for wiring into coil 4 just keep it connected to wiring an put a spark tester to it. Leave the plug in the cylinder. Spark tester can be also made from just a spark plug by bending the electrode sideways there should be a 10mm gap. Just ground the treads of the spark plug with jumper wire. Then you can start the engine. Spark should be able to jump the 10mm gap. Don't leave it running for long as it will poison the catalytic converter.
     
    #8 valde3, Feb 8, 2020
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