Rough, Long Shutdown, "Misfire" on Light Throttle

Discussion in 'Gen 2 Prius Technical Discussion' started by tidesofthesky, Jan 28, 2021.

  1. tidesofthesky

    tidesofthesky Member

    Joined:
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    Location:
    Salem, OR
    Vehicle:
    2007 Prius
    Model:
    Base
    Update:
    Finally had a chance to dig back into the Prius. I pulled up Techstream to see if I could spot any helpful data while the engine is running.

    - Checked fuel trims as suggested- they are 4-5% (Seems reasonable to me?)
    - I tracked the jolting misfires I'm feeling down to cylinder 3. I figured that out by watching the misfire counts. Every time I felt a large jolt, cylinder 3 misfire count would pop up with at least one misfire. Cylinder 2 did misfire once or twice, but 90% of them were cylinder 3. That's super helpful. I will narrow my investigation down to cylinder 3 components.

    I think that the misfiring is intermittent enough to not trigger a code. My suspicions are a marginal injector or coil pack. Any tips on what tests to do next? I just picked up an oscilloscope so I'm kind of dying to use it. Ha!
     

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  2. tidesofthesky

    tidesofthesky Member

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    2007 Prius
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    Base
    Alright I did a little research and here is my plan for tomorrow morning:

    First: Swap cylinder 3 coil pack with cylinder 1
    Check to see if misfire follows coil pack to cylinder 1.
    If not...
    Second: Perform injector disable test with Techstream, check if RPM changes.
    Cylinder Fuel Cut Test using TECHSTREAM (TIS) Software - Blog.Teknisi
    Lastly, Ohm test injector

    I'll update with the results.
     
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  3. tidesofthesky

    tidesofthesky Member

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    2007 Prius
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    Base
    Ok THE CONCLUSION! (I hope)!!!

    Moved #3 coil pack to cylinder #1. Misfire followed coil pack! Replaced coil pack and issue seems to be resolved! Will take the car on a longer drive soon to confirm.

    So if I were to do this again (diagnosing stumbling with no stored codes), I would open techstream and look at the live data in "Engine and ECT" section. Look at the misfire counts- they reset often, so you have to watch carefully. But on mine, each time I felt a clunk, I could see a misfire occur. Apparently it just wasn't enough consistent misfires to trigger a CEL. Then isolate it down to either coil pack, injector or mechanical/wiring. Hopefully one of the first 2.

    Posted via the PriusChat mobile app.
     
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  4. SFO

    SFO Senior Member

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    Which rooftop tent, and do you have any installed pictures you could share?
     
  5. tidesofthesky

    tidesofthesky Member

    Joined:
    May 18, 2020
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    Location:
    Salem, OR
    Vehicle:
    2007 Prius
    Model:
    Base
    I actually made my own tent from retired kiteboarding kite fabric. Works pretty well!
    Dimensions are about 48wx92L

    Speaking of which, camped out at the ski resort in the tent last night- no misfiring on the way there or way back! I'm pronouncing this problem officially solved. IMG_20200828_184513.jpeg

    Posted via the PriusChat mobile app.
     
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