1. Attachments are working again! Check out this thread for more details and to report any other bugs.

I NEED HELP!! MECHANICS VERY WELCOME. CHANGED INJECTORS AND NOW CONSTANT MISFIRING

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Iamnotarobot, Mar 29, 2022.

  1. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    Thanks in advance.
    I have a 2012 with 210k miles. I have been getting about 40mpg for a long time and was wanting to improve mpg.
    I removed the injectors and sent them to a company that cleans them.
    I reinstalled the clean injectors and put in a new upstream o2 sensor (just to try and see if it would help mpg). When I started the car it almost instantly started bucking and shaking like it was running on 2 cylinders.

    I checked all wiring connections and changed spark plugs just for kicks.

    Still bucking and shaking. So now I think maybe a bad coil... I unplugged 1 coil no change. I uplugged 2 coils and expected nothing to happen, but still no change. Engine still bucking with #2 and #4 coil unplugged. I unplugged 1,2 and 4 and it still was missing. I unplugged all 4 coils and the engine sounded smooth. I have a feeling this was just the electric motor that starts the car was just running non stop.....

    I am soooo confused. My only option I can think of is that the fuel injector cleaning company ruined 1 or more of my injectors. They all ohm tested around 12.8-13.1

    Also if I let it run I get a weird smell and smoke. I am starting to think I am burning up my valves or pistons !!!! AHHHHGGGGG I need help. Some direction would help.

    Thanks again
     
  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    8,947
    1,558
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Are there any codes just curious no lights on on the dash while the bucking is going on like in my car when that happens when i was chasing something it was telling me to check my coils and spark plugs it was adamant about it and had its own code and when i did so i found four rusted coils that apparently weren't firing or mostly misfiring replace them left the plugs in place ran smooth as new not saying that's your problem here i would be looking at injectors too especially if the car was running fine when you took it apart other than trying to get better mileage
     
    Iamnotarobot likes this.
  3. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    No check engine light, even when scanned no stored codes. I agree about the coils. I have had a misfire issue for a long time on start up. But after a few seconds it runs fine.
    I had a bad misfire before and it was a bag plug. The iridium tip had broken off and then started to misfire.

    I guess it couldn't hurt to change the coils.... Maybe I can test them first.
     
  4. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,847
    15,503
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Did the company supply you a report with the before/after cleaning performance of the injectors?

    The reports we would get from the service used for the PriusChat injector exchanges would look something like this:

    [​IMG]

    Sometimes the report shows the injectors really were kind of bad before cleaning (as in that example), and excellent again after cleaning. More often, it would show they were excellent before and after cleaning ... which is "bad" news in that it means there wasn't much need for the work, but still pretty good news otherwise. Either way, it is helpful to get the report, and thereby know whether there was or wasn't an injector issue before the cleaning.

    It does sound as if something hasn't gone back together right.

    Was the battery disconnected at some point during this process?
     
    Iamnotarobot likes this.
  5. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    I did not get any report from them. It was a budget ebay service. They replaced filters and seals though.
    I am curious how much that service you referenced is.

    I was going to add the fact that the battery has been disconnected for over a week, so yes it was.

    I am looking at ordering some ignition coils, but do not want to shell out the cash. I found some Hitachi brand ones for about $50 each. My mpg has become worse over the years so I think they should be replaced anyway. Who knows, maybe the coils are all having intermittent spark issues..... I am stretching here, but 210,000 miles I guess it can not hurt anything...

    I feel like something is disconnected, it is just hard to believe it is not injector related.. I guess I will try coils, then order new injectors if that does not help.
     
  6. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
    1,555
    660
    0
    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    I would buy new injectors
     
    Iamnotarobot likes this.
  7. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,847
    15,503
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Looking back over those old posts, we were paying $83.60 (including postage back to me) then to recondition a set of 4.

    It's been reported that this can lead to hard starting and poor running after reconnection, if the ECM had learned certain values (say for throttle opening, if the throttle body has been getting dirty over time), and forgotten those and gone back to defaults when the power was removed. It should eventually relearn good values, but that's not much help if the defaults are so far off that the engine barely starts or runs. The reports about this that I've read recommend thoroughly cleaning the throttle body, for a start.

    Beyond that, it sounds possible this could end up as a job for an experienced diagnostician with the instruments to match. Swapping parts might only get you so far.
     
    Iamnotarobot likes this.
  8. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    I will clean the throttle body just for kicks last time was around 150,000 with the new manifold. It always looks clean because these cars are always washing them with blow by lol. There is always a pool of blow by at the bottom/entry on intake manifold when I look.

    I will clean the throttle body and replace the coils because I have had rattling starts even after the new manifold and cleaning emission parts for a long time.

    I will wait to replace the fuel injectors even though I think they are the culprit.

    About the professional diagnostician... I normally just buy the tools I need to diagnose and repair rather than pay someone who just basically owns a tool... I am perfectly capable with the right knowledge/information and tools. If I need a $10,000 toyota computer then hey I will throw $500 in parts at it see what happens LOL.

    I think coils is a good start as they seem to wear down over time anyway. I have not been over 41mpg in a long time too. Tons of blow by too so that makes me think maybe poor spark...

    I would still like anyone's opinion as I am just throwing parts at this right now. Thanks again everyone!

    UPDATE: I just ordered 4 new Delphi Ignition Coils from Amazon ( Someone mentioned these in the forum). HERE WE GO!!!
     
    #8 Iamnotarobot, Mar 30, 2022
    Last edited: Mar 30, 2022
  9. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,446
    38,661
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Has the Exhaust Gas Recirculation system been cleaned?
     
    Iamnotarobot likes this.
  10. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    I cleaned all the emissions system at about 150,000. So it has been 60,000 since and I pressure washed them out till they were perfectly clean.
    I would say maybe I clean them too for kicks, but it has only been 60,000 miles and to be honest it did not help too much when I did (that was with the new manifold too).
    Also I can't help but think this all happened because I changed/cleaned the injectors. The battery being disconnected makes sense, but the longer I ran the engine I noticed smoke out of the exhaust. So how can the computer learn if it can not run? I think I have a bad part. The emission system clogging up seems like that would have been before the injectors came out.

    I still think it is a bad injector, but they all ohm test and there are so many counterfeit ones out there I am nervous to buy these $30 sets. I do not want to spend the money on factory toyota ones if the coils are bad.
    The fuel injector cleaning company swears they tested and cleaned with no issues, but no report. Their machine is not that type.

    Unless someone says otherwise I am starting with ignition coils, then injectors after that. I will clean the throttle body and check that little tube on the egr cooler (I think thats what it is) if I can and see how much carbon it has in it. That should be a good indicator of the coolers condition and I will not have to unhook the coolant lines. If it is clogged then I suspect even the NEW IMPROVED MANIFOLD will have clogged pathways again......... That may be leading to all the morning misfiring.

    So it sounds like my clogged emissions system might be causing my worn ignition coils to be under performing enough to misfire so bad that my unhooked battery that caused the cpu to relearn can not relearn fast enough to balance the air fuel so that the worn ignition coils fire enough to run the engine. Sounds like that is possible haha kind of..

    AHHHHH! I just wanted some extra mpg :(. Good thing I have another car, bad thing is gas prices these days.....
     
    #10 Iamnotarobot, Mar 30, 2022
    Last edited: Mar 30, 2022
  11. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,446
    38,661
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Yeah checking the pipe will give you an idea of the cooler condition, without having to pull off the cooler itself and disconnect coolant lines. If you do pull the cooler, see first link in my signature, for some tips regarding cooler disconnect without coolant spill.

    EGR passages in the intake manifold can clog pretty fast too, cylinder one seems to always clog first, and the intake is "relatively" easy to pull off for inspection. Again, more info in that link.
     
    Iamnotarobot likes this.
  12. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    Thanks, I am looking at your links now. That is genius putting those links in your signature. That will help a lot of people over the years.
     
  13. SFO

    SFO Senior Member

    Joined:
    Feb 7, 2017
    5,297
    4,235
    0
    Location:
    Northern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Where did you purchase it, and which upstream A/F sensor part # did you install ?
     
  14. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    Amazon. It is an off brand 234-9052


    To be clear I had no issues that caused me to buy it. I just want to experiment to see if my gas mileage went up after swapping it. I started the car it was missing so I shut it off and funny enough the fuel injector cleaning service put oversized o-rings on them so it was leaking gas everywhere.
    I put on new o-rings and it was still missing so I put the OLD O2 Sensor back in. OLD Sensor back in but still missing

    Do you think the computer needs to be reset again because it was learning with leaking fuel?
     
  15. SFO

    SFO Senior Member

    Joined:
    Feb 7, 2017
    5,297
    4,235
    0
    Location:
    Northern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Disconnect the 12v to reset the fuel trim mapping, then clean up the throttle body and maf, then reconnect the 12v.

    Which device are you using to scan for OBD2 codes (DTCs) ?
     
  16. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
     
  17. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    I am using torque lite app, but the blue-tooth obd scanner is generic. It is labeled OBD Scan Advanced OBD Scan Tool.

    How long should it take for the computer to reset? I just disconnected the battery again.
     
  18. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,920
    4,686
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Excellent thinking

    This is a head gasket symptom. Classic. Changing injectors, plugs, coils and egrs won't help.

    This means the head gasket is really bad. Because you have so much blowby I would replace the engine. Bad rings are also common on this model.
     
  19. Iamnotarobot

    Iamnotarobot Junior Member

    Joined:
    Jun 1, 2015
    38
    11
    0
    Location:
    Louisianna
    Vehicle:
    2012 Prius
    Model:
    III
    I have thought of that a lot and many people say bad head gasket, but my oil is clean and my coolant is clean. It is my understanding that one or both would be mixing. Coolant in oil, or oil in coolant. Both of mine are clean.
    I can handle blow by. Toyota manual states it is normal to burn 1qt of oil every 600 miles after that repair is needed. I assumed the rings are leaking. I have not looked into how to do a compression test on this car, but I think I may have learned when I unhooked the ignition coils.

    I do not see smoke out of the exhaust normally, only during this event. I never smell anything funny since the car was new.

    I can do a quick compression test, but I would have to hook up the battery again. When I hook up the battery again do you think that a compression test will mess with the learning process?
     
  20. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,920
    4,686
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    A compression test is useless and these engines do not leak coolant into the oil or oil into the coolant. They slowly leak coolant into the cylinder which fouls the plug. It rattles and shakes because it is a hybrid with a spring loaded damper in the transaxle. The electric motors in the transaxle must maintain perfect sync with the gas engine. When they don't because of a misfire, the damper tries to compensate and makes the metal to metal shake. In the early stages the leak stops as the cylinder and head heat up, usually within seconds. The plug starts firing and it runs fine. At first just on a cold start. Running like this for weeks and months makes it happen more often and longer. White smoke then occurs.

    A borescope inspection will often see a steam cleaned piston in the early stage while a leakdown or compression test is not definitive. It is possible you have introduced a second problem, but if it smooths out eventually, all the coils, plugs and injectors are fine.

    It is a very common problem, especially on an engine with high blowby and oil consumption.
     
    #20 rjparker, Mar 30, 2022
    Last edited: Mar 30, 2022