Hesitation and no codes

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Pdaddy, Feb 10, 2021.

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  1. SFO

    SFO Senior Member

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    Have you observed any radiator coolant loss in the reservoir?
     
    #21 SFO, Feb 18, 2021
  2. Pdaddy

    Pdaddy Member

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    Nope. All levels are normal under the hood.

    SM-G960U ?
     
    #22 Pdaddy, Feb 21, 2021
  3. johnnychimpo

    johnnychimpo Active Member

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    in the end what was the issue.
     
    #23 johnnychimpo, Feb 21, 2021
  4. Pdaddy

    Pdaddy Member

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    Not fixed yet. Been too cold to work on the car.

    SM-G960U ?
     
    #24 Pdaddy, Feb 21, 2021
  5. David9962000

    David9962000 Member

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    Maybe try "Chevron Techron" additive and an "Italian Tune-up"!?
     
    #25 David9962000, Feb 21, 2021
  6. Pdaddy

    Pdaddy Member

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    I took the air intake manifold off intending to potentially replace it as the dealer would have done. However I think the valves are messed up on #4 piston. They don't look seated compared to the other valves, and look like they are dropped down. I did get intermittent misfire or pending misfire on 1 and 4 but only one time during all the rumbling drives.

    Does the car need a valve job? Could this have been caused from rough idle due to air intake obstruction? Or happened on its own? At 245K miles should I consider paying for this (no idea about cost)? As to my level of skill I have only replaced rings on an old motorcycle and otherwise only replaced common failing parts.

    Appreciate insight from those who have dealt with this..... Screenshot_20210228-200533_Gallery.jpg Piston4%20both%20valves.jpg

    SM-G960U ?
     
    #26 Pdaddy, Feb 28, 2021
  7. Pdaddy

    Pdaddy Member

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    Piston 1 looks ok 20210228_195010.jpg

    SM-G960U ?
     
    #27 Pdaddy, Feb 28, 2021
  8. SFO

    SFO Senior Member

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    Can you use the copy and paste feature to put the images inline?

    Copy the image using Control-C, and then Paste the image using Control-V, makes it easy to put images in the reply box.

    It appears you're using facespace images or something, which don't show up for me.
     
    #28 SFO, Feb 28, 2021
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  9. ASRDogman

    ASRDogman Senior Member

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    Some valves will be open because the piston is not at it's highest point.
    Only 2 at a time will be, the others will be opposite.

     
    #29 ASRDogman, Mar 1, 2021
  10. Pdaddy

    Pdaddy Member

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    Shouldn't pistons 1 and 4 be synchronized and valves will be similar or is there enough variability with valve timing that this not the case?

    SM-G960U ?
     
    #30 Pdaddy, Mar 1, 2021
  11. ASRDogman

    ASRDogman Senior Member

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    One is on the compression stroke the other is on the exhaust stroke, I believe.
    Rotate the engine by hand and you can see them moving....

     
    #31 ASRDogman, Mar 1, 2021
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  12. ChapmanF

    ChapmanF Senior Member

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    It's not about timing variability, it's that pistons 1 and 4 move up and down together, but they are half a cycle apart in firing order. If 1 is up on its compression stroke now, 4 will be on its compression stroke the next time it is up.

    Having them fire together wouldn't make sense.
     
    #32 ChapmanF, Mar 1, 2021
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  13. Pdaddy

    Pdaddy Member

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    So I just need to turn the bolt on what looks like a pully on the passenger side of the engine to turn it by hand?

    SM-G960U ?
     
    #33 Pdaddy, Mar 1, 2021
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  14. ChapmanF

    ChapmanF Senior Member

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    That's how it's done.
     
    #34 ChapmanF, Mar 1, 2021
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  15. Pdaddy

    Pdaddy Member

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    I replaced the air intake manifold and problem is solved. The old one was still pretty caked up despite an attempt to clean it last summer (in my defense the focus was on the EGR cooler which took me a week to clean at the same time). Thanks for the advice!

    SM-G960U ?
     
    #35 Pdaddy, Mar 7, 2021
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  16. mr_guy_mann

    mr_guy_mann Senior Member

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    All 4 cylinder cycles are staggered. If cylinder 1 fires its plug then 180* later cylinder 3 will fire, 180*- cylinder 4, 180* then cylinder 2.

    Cylinders 1 and 4 are companion cylinders- each is 360* apart / out of sync. When 1 is at TDC compression stroke, 4 is at TDC exhaust stroke and vice versa. 2 and 3 are also companions- 360* apart from each other but staggered 180* from 1 and 4.

    Every 4 stroke engine design will complete one full cycle of each cylinder every 720* (2 revolutions). 180* for intake stroke, 180* for compression stroke, 180* for the power or expansion stroke, 180* for the exhaust stroke. Then begin again.

    Posted via the PriusChat mobile app.
     
    #36 mr_guy_mann, Mar 8, 2021
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