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Occasional Jerking/Shuddering, Lumpy/Rough Idling Engine

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by tangerino, Mar 14, 2022.

  1. tangerino

    tangerino Junior Member

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    Hi Priuschat,

    I've been noticing some shuddering/jerking from my Gen 2 recently and am not too sure what to make it of it. Symptoms are:
    - A bit of shaking through the steering wheel and seat (but no audible noise) on what seem to be mostly random occasions so far - right after starting (sitting idle), at low speed, and when the engine turns off when sitting at a light. It's not very consistent though, I'm still trying to figure out what the pattern is. No problems while turning though, so it doesn't seem to be my CV axle (which does have a torn boot I've been concerned about).
    - Most alarming is that twice now on the highway the CEL light was *flashing* for maybe a minute before going away. I checked the OBD2 codes later on, but the only code was P0420 (which I've always had since installing my aftermarket catalytic converter). So I don't know what the flashing was indicating exactly, but my guess from what I've read is that it could be some intermittent engine misfiring? Is there any way I can confirm this if it didn't set an engine code? Is there compression data I can check via the OBD2? Maybe check the RPMs?

    My Gen 2 is at about 105k so I'm thinking my spark plugs are going out early and I should replace them now rather than wait for 120k. But it sounds like there could be a number of other causes: coils, injectors, dirty PCV, dirty MAF, or even engine mounts, clogged cat, unbalanced tire, etc. so I thought I'd check here before I start doing work on it. (My engine oil and coolant levels look fine btw) Any suggestions for how I can diagnose further? Would it be a bad idea to keep driving as-is and just wait for an engine code to set?
     
    #1 tangerino, Mar 14, 2022
    Last edited: Mar 14, 2022
  2. PriusCamper

    PriusCamper Senior Member

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    Sounds like you're describing a car that is dreadfully low on engine oil... As for the running rough when it's cold and sometimes on shutdown at a red light, that's a common characteristic of an Atkinson type engine, especially as it gets older. Fairly normal, but could point to trouble if it gets worse, especially if you aren't keeping up on basic maintenance like checking the oil level and such.
     
  3. tangerino

    tangerino Junior Member

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    So I checked the oil level after the first flashing CEL, but it was at the top fill mark and looked pretty clean (had it changed <1500 mi ago) FWIW.

    I haven't had any issues with losing oil between changes and do check the oil level/color from time to time (maybe every third fillup). Hoping it's not engine damage :/

    Re: shuddering at red lights, I think that's probably happened before all of this; I may just be more aware of it right now trying to figure out when this shaking tends to happen.

    Biggest safety risk at this point seems like possible hesitation when accelerating. I do sometimes notice a bit of hesitation (accelerating from a stop) along with the traction control light coming on, but that may be something else (will get alignment checked).

    EDIT: Side note, I did also just slightly overinflate my tires to 41 front / 39 rear per other threads. I may just be feeling a lot more of the road right now as well, but it's the flashing CEL that has me most concerned right now. I felt shaking sitting at idle too, so that rules out this being a tire issue.

    It's a bit baffling to me that the engine would misfire but apparently not long enough to log a code... Would setting up Techstream be useful here?

    Reading this I wonder if I might have bad fuel injectors, maybe they got damaged since I have run the tank low (to flashing) before: https://www.vehicleservicepros.com/service-repair/underhood/article/21029342/attacking-no-code-misfires Maybe a little fuel injector cleaner would be worth a try?
     
    #3 tangerino, Mar 14, 2022
    Last edited: Mar 14, 2022
  4. PriusCamper

    PriusCamper Senior Member

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    My gen2 traction control light comes on more than it use to now that I'm at 270K, especially one pothole near my house when going downhill... Glad you check your oil often. I get so frustrated with so many people that never learned how.

    If you want to spend $150 and get rid of most of the hesitation get one of these, it's a very easy part to swap out. Made a big difference for me. Some don't agree: https://www.redbullet.net/
     
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  5. tangerino

    tangerino Junior Member

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    I guess the problem isn't occurring often enough to worry too much about yet (was fine today), and it's intermittent enough that bringing it to a shop probably wouldn't be much help either. For now, I'm thinking I may try using some Techron to ensure the fuel injectors are clean (if that's safe for the fuel bladder) and also clean the MAF, as a first step.

    If things get worse/consistent, I'll replace spark plugs, coils, PCV as one job (seems to be a good idea at 100k anyway) and maybe also clean the throttle body and intake manifold too.

    Also possible my aftermarket cat has clogged up after a year; it's always thrown occasional P0420 codes though (figured just low efficiency, not clogged): Amazon.com: Customer reviews: AUTOSAVER88 Catalytic Converter Compatible with 2004-2009 Toyota Prius 1.5L Direct-Fit (EPA Compliant). I guess I can check the temps via an infrared thermometer rather than try to do an exhaust backpressure test?
     
    #5 tangerino, Mar 15, 2022
    Last edited: Mar 15, 2022
  6. PriusCamper

    PriusCamper Senior Member

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    Try replacing your downstream 02 sensor for Cat problem... And yes, if you haven't done plugs, MAF & throttle cleaning and reset computers by disconnecting 12v for a few minutes, do that first.

    I'd worry about the deeper level of injector cleaning and inspecting, replacing PCV valve as next stage if you don't get results. Most of the Prius I've worked on have improved greatly when it comes to decreasing severity of these symptoms just from doing these regular 100K mile maintenance steps. Main value for me in doing these is I wanna see what the spark plugs look like because there's lots of engine health info in seeing those.
     
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  7. tangerino

    tangerino Junior Member

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    Just confirmed misfiring, I got a P0301 code set just now after a few CEL flashes.

    Will probably change the plugs this weekend, thinking maybe some Amazon iridium ones will do:


    Or is it best to go OEM for these, just in case of counterfeits? May try RockAuto: 2007 TOYOTA PRIUS 1.5L L4 ELECTRIC/GAS Spark Plug / Coil-On-Plug Boot | RockAuto Found that the Toyota manual recommends: Spark plug type: DENSO SK16R11 NGK IFR5A11 Spark plug gap, mm (in.): 1.1 (0.043)

    I guess I may as well change the COP boots while i'm at it? More Information for STANDARD MOTOR PRODUCTS CPBK624
     
    #7 tangerino, Mar 16, 2022
    Last edited: Mar 16, 2022
  8. BuyJapanese

    BuyJapanese Member

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    Get good spark plugs. OEM from rock auto is a good choice. I wouldn’t change COP boots but maybe order one OEM coil to have on hand in case that ends up being the issue. I support MAF cleaning an Techron also. Make sure to use dielectric grease with your new spark plugs, that’s important and often neglected.
     
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  9. Another

    Another Senior Member

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    Why not NGK?
     
  10. tangerino

    tangerino Junior Member

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    Sadly I broke the 10mm aluminum bolt on the second coil packs while torquing it to what I thought was 10ft-lb... I was able to remove the two pieces but not sure what to do now.

    Is there any donor bolt I could take from somewhere else on the car? Any idea if it's a standard size I could order? I had I feeling I shouldn't have trusted the uncalibrated torque wrench I just got (goes up to 80ftlb max).
     
  11. BuyJapanese

    BuyJapanese Member

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    A 10-80 ft lb torque wrench is liable to be imprecise at the extremes. I just go by feel on those. You can probably use one of the bolts that holds the airbox, or that holds the electrical box behind the spark plugs. Better yet just take one of your good bolts to a hardware store and find one with the same size and thread pattern.
     
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  12. tangerino

    tangerino Junior Member

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    The relay box and other screws I found around the car were all a bit too shallow. I ended up digging up an IKEA bolt that seemed to be the same thread pattern (presumably some M* pattern). I tied a zip-tie under the head to shorten the effective length and it seemed to torque in just fine at that point; coil pack was as snug as the other 3. I was afraid of the plastic melting under heat, but the coil pack head and connectors are all plastic adjacent to that bolt, so I'm not sure that will be a problem. Will probably go buy a proper replacement bolt (or a set of metric bolts) but this seems to be working after a brief test.

    Spark plugs were definitely the culprit. Engine runs nice and smooth now. Old spark plugs had corrosion (white residue) all on the electrodes and green corrosion at the hex base (will post a picture later). Maybe they would have benefitted from dielectric grease (not sure Toyota does that from the factory). Hoping I'll see an MPG increase. (I did end up getting OEM Denso plugs)

    Boots looked like they were in nice shape and I saw no cracking so I left them as-is.

    I'm thinking I may go ahead and get my oil changed now even though it's only been 3.5 mo and ~1600mi, since I've been told unburnt fuel could have gotten into the crankcase and contaminated the oil. It's only been intermittently misfiring for less than two weeks (drove probably <100 mi like this and <20mi since the P0301/P0302 code set) though; am I overthinking this? The amount of unburnt fuel in the oil might just be negligible. My MPG didn't seem to drop significantly during all this either.
     
    #12 tangerino, Mar 18, 2022
    Last edited: Mar 18, 2022
  13. tangerino

    tangerino Junior Member

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    I think I'll end up going back in with a proper 20-200 in-lb torque wrench and then make sure the spark plugs are right at 13ft-lb. Reading some scary stuff about the potential consequences of under/over-torquing spark plugs and realizing now I've underestimated the importance of precise torque (not just 'snug' + 1/16 turn like I've seen online). Also wondering now if the use of socket adapters (I had to adapt tools I have in 1/4", 1/2", and 3/8" to get the job done) threw off the torque wrench that I did use (5ftlb-80ftlb)
     
    #13 tangerino, Mar 18, 2022
    Last edited: Mar 18, 2022
  14. BuyJapanese

    BuyJapanese Member

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    Do you park inside or outside? How long are your typical drives? Condensation can collect in oil in winter especially if you're parking outside, and can cause problems.

    I would suspect at this point that you're losing fuel efficiency, and fouling spark plugs faster, because of the aftermarket cat you mentioned in your first post. The computer gets misleading readings from the A/F and o2 sensors because the cat isn't doing what it expects, it adjusts fuel trim badly, spark plugs get fouled faster, etc. Expect to have the same problem again unless you upgrade to a cat that your car likes.
     
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  15. tangerino

    tangerino Junior Member

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    Parking outside in WA where winters are constantly wet. I tend to make 15 minute drives too, so it sounds like those kinds of conditions.

    I think the plugs I took out were the original ones that came with the car so they were beyond their life anyway; hoping even if fouling faster than normal that this new set can get me another 50k.
     
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  16. edthefox5

    edthefox5 Senior Member

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    Plugs need to be changed at 100 k miles not 120.

    If you can’t tighten cop bolt without stripping it using T Wrench I wouldn’t go after the plugs with it.

    This forum has 2 obsessions one is the MAF the other is a torque wrench.

    Unless you bought plugs at the dealer you probably bought counterfeit plugs it’s big business now. Especially Amazon. You will find out real soon.

    I would have changed the valve cover gasket high failure item. If you looked in spark plug well before pulling plugs you may have seen oil weeping into spake plug well.

    Replace the water pump belt. Take Belt off spin the water pump impeller see how it feels. Same with belt idler, Put new belt on not super tight let it break in by running in inspection mode for 15 minutes then tighten up belt again. Not super tight lol..

    Clean throttle body lubricate its butterfly spring.

    Buy 2 gallons of Toyota LLC. Take rad cap off open rad dump petcock on bottom drivers side dump rad into container flush down drain. Close petcock fill it back up to top of neck with LLC.
    Check it’s level next day.

    Do rad again next month.
     
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  17. tangerino

    tangerino Junior Member

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    Hoping if I use a in-lb wrench I'll be in better shape (200 in-lb max) on a second go.

    I heard about counterfeits. I bought mine from Amazon (direct, not third-party seller) and didn't see too many bad reviews:
    I guess I could have been more patient and tried ordering direct from Denso/Toyota but was afraid continuing to drive with misfires would do more harm. I guess we'll see how long they last; 50k or even 30k is fine with me since I don't drive much.
     
  18. tangerino

    tangerino Junior Member

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    Been about 150 miles on the new plugs and the engine has been nice and smooth, no misfiring or engine codes anymore.

    But my MPG seems to be lower (about ~40mpg so far vs ~45 just before this). Possible symptom of counterfeit spark plugs? Or imprecise gapping? I didn't verify the gapping before I installed; they looked okay by eye but I didn't want to risk scratching the electrodes on this type of gauge: https://www.walmart.com/ip/Hyper-Tough-Steel-Spark-Plug-Gap-Gauge-Automotive-Tool-Model-4706/132932441?wmlspartner=wlpa&selectedSellerId=0&wl13=2385&adid=22222222277132932441_117755028669_12420145346&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=501107745824&wl4=pla-293946777986&wl5=9033292&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=local&wl12=132932441&wl13=2385&veh=sem_LIA&gclid=CjwKCAjwuYWSBhByEiwAKd_n_sikZQZ5ndHTcHg8YKzGoevv9e1jqXWlPRSbbdelq87z1QXgsJI4ABoCJ3gQAvD_BwE&gclsrc=aw.ds

    I went ahead and ordered some OEM spark plugs. Will try those and see if that helps. Will also retorque everything to spec with a new wrench, in case that helps.

    I did also unplug the 12V after install to get the ECU to relearn the idle on the new plugs, if that matters here.
     
    #17 tangerino, Mar 28, 2022
    Last edited: Mar 28, 2022
  19. dolj

    dolj Senior Member

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    No, never try to adjust the gap on iridium plugs. Yes, trust that they are pre-gapped. If, by chance, they have been bashed in transit, that should be very obviuos and you would need to take it back for replacement rather than try and re-gap it.
    That sounds pretty standard.
     
  20. dolj

    dolj Senior Member

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    No, never try to adjust the gap on iridium plugs. Yes, trust that they are pre-gapped. If, by chance, they have been bashed in transit, that should be very obvious and you would need to take it back for replacement rather than try and re-gap it.
    That sounds pretty standard.
     
  21. BuyJapanese

    BuyJapanese Member

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    150 miles is a bad sample size. Most likely cause is random variation, second most likely cause is disconnecting the 12V.