Misfire and Air-fuel ratio imbalance

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by inafix, Feb 20, 2019.

  1. inafix

    inafix New Member

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    Greetings. I've found this forum to be exceptionally helpful in the past. Looks like its time to finally join in on the conversation. I had a 2008 Prius for a few years, it was a great car. I drive for Uber and Lyft for a living. Due to the age of the car and rules in the city I live in, that car was too old to continue using. I found a 2014 Prius with 206,000 miles on it and decided to take a bit of a gamble on it. It was previously a medical transport vehicle. Mostly highway miles. It seemed to be in very good condition for the mileage. However, not much more then a month after buying it my check engine light came on.

    P0301 - Cylinder 1 misfire detected
    P219A - Air-Fuel ratio imbalance

    Regrettably the first thing i did was buy 4 new Ignition coils and install them. They are Duralast brand from Autozone. A short while later the engine codes came back. At this point i did a bit more research on the forum here and other places. I installed new Bosch Iridium spark plugs and put a can of Seafoam injector cleaner in the fuel tank. After removing the spark plug in cylinder 1 I did take a look and didn't see any evidence of coolant, nor is my coolant tank low. A short while later, again the check engine light came on.

    I'm no expert with this sort of thing but I'm very interested in cars and have been trying to learn more. It seems to me that its not misfiring at all on cold starts. sounds good. Once it heats up and I'm on the highway is when i start to notice things. It seems a little rougher and maybe a bit stuttery. Occasionally there is also a noise that sounds a bit like a knocking.. its hard to describe... It doesn't do it all the time. I'm not even sure this sound is coming from the engine.

    I took it to a local shop specializing in hybrids. They recommended against the Bosch plugs for starters. Thats not a big deal though, I can switch those out again for Denso. they ran a "Block integrity test" trying to determine if i was having head problems. The technician concluded there was no signs of hydro carbons in the cooling system. The color changed a bit but not enough to say for sure that's the problem. I've included a picture of the test fluid. He didn't drive it enough to notice any misfiring.

    Where would you folks recommend i go from here? The shop wanted to do a compression test and inspect the ignition components next, for a rather hefty fee. I have a friend that is going to help me do a compression test. I'm looking into cleaning out the EGR system. I noticed that was pretty highly recommend on posts with similar problems.. I'm not getting any codes for the EGR system though. Any thoughts on the Bosch spark plugs and Duralast ignition coils? I still have the original ones.

    Thanks for your time!
     

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  2. tankyuong

    tankyuong Active Member

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    You probably have a blown head gasket. I tried that Test and still had a blown head gasket
     
  3. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Bypass compression and go straight to a leak-down test? This is maybe easier with a Prius too, with the unorthodox start up: one cylinder at a time is pressurized, and then you go looking for air leaks. There's a special gauge as well. Most garages should be familiar with this.

    Kind of a long-winded video, he has problems with his (new) gauge, but interesting info:



    It seems a common refrain, that coils and plugs are replaced, and turn out to not be a problem. If there's a misfire code for a specific cylinder, just moving the coils to different cylinders and seeing if the code changes is cheaper.
     
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  4. padroo

    padroo Senior Member

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    I agree with Mendel on a cylinder leak down test. For one thing, you need Techstream to do a compression test.
    Second a cylinder leak down test can show air bubbles in the cooling system and help locate where the actual problem is. Read up on cylinder leak down test.
     
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  5. inafix

    inafix New Member

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    Thanks for the info! I'll look into the leak down test.
     
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  6. Raidin

    Raidin Active Member

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    Long after I blew my head gasket, I also ran into the same two codes you did. Only difference was that mine was misfiring on #4. My mechanic tried the old swap the coil trick. I did get the codes back two times, but both of those times they were just the P219A. The misfire code was gone.

    It has been over a week now and no CEL since I reset the codes twice after the coil swap.
     
  7. The Critic

    The Critic Resident Critic

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    It is unlikely that the P219A is due to coils. This fault generally sets if you have an air/fuel ratio imbalance. The only two causes I can think of, for an AFR imbalance between cylinders, would be a bad injector or a valve sealing issue.
     
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  8. Raidin

    Raidin Active Member

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    Thanks to PriusChat and many of the great users here, I talked to my mechanic about the EGR system, which he didn't realize was different than every other Toyota. The codes (plus the low speed engine rattling noise) were all due to clogged EGR ports inside the intake manifold. We followed Toyota's TSB and replaced the manifold because it would have taken too long to clean, and cost a lot more in labor than the new manifold.

    Long story short: new manifold + EGR valve cleaned + we left the EGR cooler alone because it is difficult to clean and will replace it when it needs it = no more rattling noise or codes. All gone. Car drives like new, and even makes a loud intake sound which I never heard before under hard acceleration.

    Pictures of each intake port, cylinder 1 being least gunked up, all the way to 4 being most gunked:

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    #9 Raidin, Mar 24, 2019
    Last edited: Mar 24, 2019
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  9. Raytheeagle

    Raytheeagle Senior Member

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    Good visual;).

    Clean the whole circuit and you’ll be good to go:).

    You can always buy spares and have them ready to go for the next round to ensure it is all clean(y).
     
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  10. Raidin

    Raidin Active Member

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    That's what I was thinking. I will try to clean the manifold, and if I am able to, I can use it next go around then clean the new one I have in there now, and just keep doing that. I may try to do that for the EGR cooler as well. I need to research various ways to clean carbon buildup. At least this way I have the time to clean it and not waste it on labor costs.

    You have no idea how relieved I am to be done with that crazy rattling noise...
     
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  11. Raytheeagle

    Raytheeagle Senior Member

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    Oh I can imagine the feeling of relief;).

    I’ve seen that feeling or the smile of avoidance after doing the job:).

    A pressure washer is the best way for the cooler (you can go the the car wash and use that) and a set of Harbor freight brushes will get the intake manifold good, then finish it off with carb cleaner and you’re all set for the next round(y).
     
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  12. padroo

    padroo Senior Member

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    How well do these plastic intake manifolds clean up?. Some plastics are sensitive to harsh chemicals and can be damaged
     
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  13. Raytheeagle

    Raytheeagle Senior Member

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    Well I’ve cleaned over a handful with carb cleaner;).

    As far as getting It spotlessly clean, I leave that to someone more OCD than me:).

    At the last meetup, @Grit took care of 2 circuits, so he can expound upon the condition pre and post(y).
     
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  14. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    The intake manifold doesn't mind Oxi-Clean solution. It does mind something like vinegar though: it'll colour the brass-coloured threaded inserts.

    The interior of the EGR passages is somewhat rough, impossible to thoroughly clean I found. The main passageways, from throttle body on through, are pretty smooth, and you can get it pristine.

    @Raidin having to get a new intake manifold is a bit of a sand-pounder. Maybe he's got the updated number though, so that'll help. Sand-pounder number two: not touching the egr cooler. That should be dealt with asap.
     
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  15. Raidin

    Raidin Active Member

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    He felt that any issue with the cooler will result in a code, so we'll know. If he were to clean it, it would cost me a lot in labor, so I will just have to consider cleaning it myself someday or just replacing it when the time comes. I don't mind spending the money for convenience since my time is so limited.
     
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