Rough, Long Shutdown, "Misfire" on Light Throttle

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

  1. tidesofthesky

    tidesofthesky Member

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    Hello everyone,
    My Prius has had rough shutdowns for a while, but it hadn't bothered me much. But on this last trip (about 3000 miles), it got a lot worse. When I got to a stoplight, the engine would just sputter, like it was misfiring, for a long time, shaking the car. The final straw was that while driving, it began to do (what feels like) the same thing. But only in very specific circumstances. It seems to only do it at like 0-25% throttle. Anything more and it runs smooth. But with light throttle, it just feels like it is misfiring all over the place. When in cruise control, when we come up over a hill and start going down, it would "misfire". But if I either step on the gas, or turn off the cruise and coast, it is smooth. The problem seems very consistent- don't remember for sure if it does it when the car is first started up, but for our whole drive yesterday, and the day before, it was doing it. Just tried to avoid that low throttle area. I've been doing a lot of searching, but haven't found anything that sounds quite like what I'm experiencing. No check engine light. 2007 Prius, 377k miles.

    I found a video of something that sounds similar to what mine is doing, but mine is just doing it a LOT more.


    Any ideas of what this could be? My initial thought was something to do with the Start/Stop system. But I then started to suspect the transmission. Is it possible for a CVT to begin having problems only at a certain gearing (what would equate to light throttle)? Has anyone had something like this happen when the car needs a tune up? IE, should I check plugs, coils, maf, clean intake, etc? Runs great otherwise, idles excellent. I'm not one for throwing parts at a problem. This seems like it should be pretty obvious cause its so pronounced!

    -This trip was in pretty cold temps- nights getting down to 20F, driving during the days from 20-30F.
    -We did have a rooftop tent on the car for this trip, car was pretty heavily loaded.
    -Engine uses almost no oil (about 1/4 to 1/2 qt over 4000 miles when driven really hard).
    -I changed the transmission fluid with genuine toyota WS transmission fluid about 10-20k ago.
    -Recently changed inverter, but I'm pretty sure the rough stops were already happening before that.
    -No CEL (Well, I do have a CEL actually, but it's a p0016 and p1121 for something to do with the heat storage system- been there for a while).
    -Brake actuator barks a bit when it's cold. Changed the actuator about 40-50k ago with used one from junk yard.
    -Original traction battery- seems to still work just fine. I can get about 47mpg in the summer, 40-42 winter.
    -I'll hook the car up to techstream tomorrow and see if there are any codes stored that can't be read with my bluetooth obdII that I used on our trip.
     
  2. dolj

    dolj Senior Member

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    Even though your profile says a 2007 base Prius, your video is showing a Gen 3 Prius. Maybe the guys over in the Gen 3 forum would have a better idea because I can't really hear or see anything happening.
     
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  3. tidesofthesky

    tidesofthesky Member

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    my Prius is a 2007 Gen II. Like I said in the post, that's just a video I found of a car doing something similar. Mine is much worse, but it's the clunking noise I wanted to point out(what ive been told is it is the vehicle "positioning" the ice before shutting it down). Mine just clunks and clunks and clunks.

    Posted via the PriusChat mobile app.
     
  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Engine coolant level stable?

    377k miles is a LOT, carbon build-up causing dieseling?
     
    #4 Mendel Leisk, Jan 28, 2021
    Last edited: Jan 28, 2021
  5. tidesofthesky

    tidesofthesky Member

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    Yeah I'll double check the coolant level, but it's always been stable. I don't think it's drinking coolant.

    Carbon build up could be it. I would just think if that was the case it would run poorly in more of the power band than just low throttle. But I'm not familiar with that type of problem or what symptoms it might cause. I did read that the start/stop system has a carbon catch system in the intake that catches unburned fuel (because intake valves stay open for part of compression cycle- atkinson). That way the unburned fuel gets used up, but if the intake is really dirty, maybe more unburned fuel is getting trapped in there and keeping the car running poorly when it should shut off?

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  6. tidesofthesky

    tidesofthesky Member

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    EDITED TO INDICATE I CLEANED MAF, NOT EGR. FACEPALM

    UPDATE: Cleaned MAF and throttle body and it seems to have completely fixed the issue (based on a short test drive). ICE start and shutdown are smooth. No clunking or weird behavior while driving.

    Honestly, it wasn't THAT dirty (no massive buildup in it). But it was dirty. Got it cleaned out in about 20 minutes. There does appear to be some oil or something below the throttle body in the intake manifold. Is this normal? I'll have to do a search on the forum.

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    #6 tidesofthesky, Jan 28, 2021
    Last edited: Jan 29, 2021
  7. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Assuming it's somewhat sim to 3rd gen, that's likely (in most part) due to PCV input into the intake manifold. And maybe a bit of oil spit-back from the intake ports.

    An Oil Catch Can along the hose between PCV valve and Intake Manifold may help.
     
  8. dolj

    dolj Senior Member

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    Just to stop misinformation from spreading, as mentioned in many other threads on this site, the Gen 2 does not have an EGR system.

    Perhaps you meant you cleaned the PCV valve and maybe also cleaned out the PCV plumbing.
     
  9. tidesofthesky

    tidesofthesky Member

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    Hey, thanks for catching that. Yeah, I meant that I cleaned the MAF sensor. Didn't mean to spread misinformation! Woops.

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  10. tidesofthesky

    tidesofthesky Member

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    Ok, false alarm, I drove if up go the mountains and it's doing exactly the same thing as before. Any other ideas?

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  11. edthefox5

    edthefox5 Senior Member

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    Lol. Clean the maf...

    you have 378 thousand miles on the engine.....
     
  12. tidesofthesky

    tidesofthesky Member

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    Ok here is a link (https://photos.app.goo.gl/1yYryaPHJmwUiNbE7) to what the engine is doing. I was just sitting and idling this morning and it started "misfiring" like this (I put it in quotes because I'm really not sure what it's doing). Every time it makes that noise if shakes the car. Sorry it's a little hard to hear over the fan noise (when I turn off the AC the engine turns off).

    Runs great at higher RPMs, and most of the time it idles perfectly as well. But I'd say at like 1-10% throttle, it does this hickupping misfire thing. I would blame the transmission, but I wouldn't think that would effect the idle. I'd blame an injector or spark plug, but I would think I'd have some sort of misfire code.

    Yep! Its been going strong at 378k! Just got back from a 3000 mile trip in it. I like the car so I'll swap the motor or transaxle if that's the issue. Just trying to narrow it down.

    Not sure how it can run like this and not trigger a code. I guess I still haven't checked other modules in techstream.

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  13. dolj

    dolj Senior Member

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    Have checked your engine mounts?

    I notice you have your MIL (message information light a/k/a CEL (check engine light)) on. It would be extremely helpful to know what problems the ECM is reporting.
     
  14. tidesofthesky

    tidesofthesky Member

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    Thanks! I haven't checked the engine mounts. I'll take a look. This problem doesn't seem to be consistent- it seemed fine on a drive the other day, then on the way back from skiing it was going crazy. So I would question something like motor mounts because I would think that would produce a more consistent symptom. But that's just me guessing, I have no experience with that. Definitely worth taking a look!

    As for the CEL, I mentioned it in the post, but it's insanely long so I get why you missed it!

    "No CEL (Well, I do have a CEL actually, but it's a p0016 and p1121 for something to do with the heat storage system- been there for a while)."

    I double checked recently that those are the only stored codes. But I haven't looked in techstream yet to see if there are any pending codes in other modules that might not be showing up on the bluetooth obdII. I'll check that tomorrow.

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  15. SFO

    SFO Senior Member

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  16. tidesofthesky

    tidesofthesky Member

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    Hey, thank you so much for the reply. I think I was mistaken when I said P0016. Pretty sure the actual code is P1116. So sorry. I've had a lot going on lately . P1116 has something to do with the cooling heat storage system I believe.

    I did have a P0016 when I bought the car and replaced the chain and tensioner to repair it.

    I just started getting a p0300 code- random misfire. Which is good! At least the car is recognizing what's going on.

    I picked up a new pcv valve, haven't had a chance to change it yet. I'm going to take a look at the plugs while I'm in there and see what I find.

    Any thoughts on a sensor that could cause this but not trigger a code? Already cleaned the MAF.
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  17. SFO

    SFO Senior Member

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    Here is the workup for DTC P1116 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip1116.pdf

    Here is the workup for DTC P1121 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip1121a.pdf

    --

    Here is the workup for DTC P0300 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0300.pdf

    The plugs could be old (over 100k miles), there could be a leaking valve cover gasket (notice any oil on the plugs), the coils could be aging or there could be carbon tracking, or the fuel injectors have gone the distance and need a proper cleaning or replacement.

    The list for DTC P0300 is long, but doable :
    • Open or short in engine wire harness
    • Connector connection
    • Vacuum hose connection
    • Ignition system
    • Injector
    • Fuel pressure
    • Mass air flow meter
    • Engine coolant temperature sensor
    • Compression pressure
    • Valve clearance
    • Valve timing
    • PCV hose connection
    • PCV hose
    • ECM
     
  18. tidesofthesky

    tidesofthesky Member

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    Ok I had a few minutes to look at the engine this afternoon.

    -Replaced PCV valve
    -Noticed crack in PCV hose, fixed that.
    -Pulled coil packs, they're dry and look fine as far as I can tell.
    -Pulled one plug, pic below. Looks normal to me.
    -NOTICED THE SERPENTINE BELT WAS SUPER LOOSE- LIKE ABOUT TO JUST FALL OFF.
    This is the most worrisome to me- does the Prius have an overheating dummy light? I'm a bit worried that the water pump hasn't been turning well and the engine is overheating?

    I put things back together and did a test drive- still misfiring.

    Next step will be compression test and pulling all 4 plugs.

    PXL_20210204_223514931.jpeg

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  19. SFO

    SFO Senior Member

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    A bunch of lights will appear, they may trigger around 100C/212F. I set a warning on Torque for 200F, it was very useful when a belt came off at highway speeds, it offered me a 10 second advance warning before the xmas lights appeared.

    Have you checked the short/long fuel trims with techstream?

    What is the MPG currently, and historically?
     
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  20. tidesofthesky

    tidesofthesky Member

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    Sorry, I think I tried to respond a while back but must have not gone through. I haven't had a chance to dig back into the car. It's on my long list of things to do.

    That is great to know that there are lots of lights indicating overheating. Glad to know that's not my issue.

    I have not checked the fuel trims, I'll put that on my to do list.

    Historic MPG has been 42 winter, 46 summer but the last 3000 mile trip was with a rooftop tent, so the average dropped to 36ish. So I don't have a good comparison, although 36 mpg with a rooftop tent averaging 70-80 felt reasonable.

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