Would a loose spark plug throw an engine code?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Bitterbuffaloh, Jan 14, 2017.

  1. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    Went to change the spark plugs in my 2008 prius and spark plug #1 was a new one, previous owner must have had them done. So I placed the sparkplug back and went on my merry way. I averaged 38-39 mpg around town and that felt like a bit low. Not sure if I seated the spark plug correctly, I torqued it to spec but the spark plug is invisible to sigh since it's way in the engine, so who knows. I was wondering if any missfiring thats causing bad fuel economy would show on an autozone free scan? It's too cold outside right now to go pulling spark plugs.
     
    #1 Bitterbuffaloh, Jan 14, 2017
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  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Just to clarify, you mean the first plug you removed looked near-new, so you put it back, decided to leave things as-is? What torque did you use, and any lube on the threads? Also, what's the miles on the odometer?
     
    #2 Mendel Leisk, Jan 14, 2017
  3. TWOPrius

    TWOPrius Junior Member

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    #3 TWOPrius, Jan 14, 2017
  4. edthefox5

    edthefox5 Senior Member

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    Not a lot of info. Is the car new to you? Him many miles?
    Are there dash board alarms?

    Assuming your misfiring and it has thrown a code if more than 150,000 miles it's probably the cop too. If one cop is bad I would replace all of them.
    There a maintence issue really. Take cyl 1 cop off and look at the boot carefully for cracks that will leak hi volt to ground. If one cop cracked the rest aren't far behind.

    If really high mileage be aware main bearing failure sometimes causes a misfire code to be thrown. It's symptoms are a misfire that bounces form cyl to cyl. In beginning stages of main b failure engine will knock under load.

    If car new to you go to Toyota.com/owners and join the forum and post the cars vin. You will see every event the car has seen an authorized Toyota dealer service center. May have some interesting info and the reason the car was sold.
     
    #4 edthefox5, Jan 14, 2017
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  5. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    Car doesn't have any check engine lights on a dashboard. It is a 130k Mile 2008 prius which I just received about 2 months ago. I'm going through some maintenance and wanted to check spark plugs. I pulled the first spark plug and it was NGK and looked about 40k miles old, so I estimate it was done in 90k miles. I said good to myself, saved some time, put some antiseize on the plug and grease on the top and torque it to spec and went on my merry way.

    It seems like ever since I'm getting worse gas mileage. So I'm thinking I might have not seated it right. It's too cold outside to pull the plug and put it back in. So I was wondering if any type of missfiring would show up on an autozone scan. So I'll know it's at least worth getting some garage time in at my friends house to re install the spark plug.
     
    #5 Bitterbuffaloh, Jan 14, 2017
  6. edthefox5

    edthefox5 Senior Member

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    No lights on dash or mfd no codes have been logged. Why do you keep saying misfire? Is the Car running bad?

    Worse mileage is because it's cold out.
     
    #6 edthefox5, Jan 14, 2017
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  7. JC91006

    JC91006 Senior Member

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    The spark plugs on a prius look pretty new even with 100k miles on them. Not sure how you were able to determine they were 40k miles

    Anyways, those spark plugs don't require grease or antiseize. Just install as is. You might have over torqued with the added antiseize and grease, it acts like a lubricant.

    Wait till it's warmer and just change them all, it's easy and cheap. The lower mileage is normal when it's cold out and you are using the heater

    I think ngk might be new, as denso are the normal plugs that come with the prius
     
    #7 JC91006, Jan 14, 2017
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  8. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    I ran them over to my neighbor who is a more experienced wrench than me and maintains a few priuses for customers. He estimated the mileage on the NGP plugs.
     
    #8 Bitterbuffaloh, Jan 14, 2017
  9. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    What's 'mfd no codes'? Thanks for the help btw.

    Will the toyota.com/owner records show more than the printed toyota dealership records? I've got a fat stack of papers, car was babied, but most repairs have very little info. Just "owner requests xxxxxx mileage maintenance".
     
    #9 Bitterbuffaloh, Jan 14, 2017
  10. JC91006

    JC91006 Senior Member

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    I had a prius with original plugs and 165k miles, still running fine, just a little carbon buildup on the tip of the plugs.
     
    #10 JC91006, Jan 14, 2017
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  11. wjtracy

    wjtracy Senior Member

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    we've had a few cases of loose plugs causing rough running.
     
    #11 wjtracy, Jan 14, 2017
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Torque spec on 3rd gen is 15 ft/lb, fwiw. Coming from Honda, where the shop manuals always recommend anti-seize, I applied a very think application when I inspected ours, and reinstalled with 13 ft/lb torque.

    So what torque did you use, what do mean by "spec"?
     
    #12 Mendel Leisk, Jan 14, 2017
  13. Lucifer

    Lucifer Senior Member

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    I replaced my gen2 plugs with an aftermarket set and one misfired, i try a code, I put oem plugs in, back to +50 mpg and no code

    If the plug has no spark, it misses, if the plug got gummed up while inserting it, no spark, it's best to remove the wipers and everything in the way to get at the plugs, it's not difficult, just takes a technique.
     
    #13 Lucifer, Jan 14, 2017
  14. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    So with the misfire the code showed up in an OBD scanner? I can take mine to autozone and see.
     
    #14 Bitterbuffaloh, Jan 14, 2017
  15. JC91006

    JC91006 Senior Member

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    A misfire will give you a warning light on your dash
     
    #15 JC91006, Jan 14, 2017
  16. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    Ok, I'm probably fine then. Bad gasmileage probably a result of it being cold up here, short trips, and infrequent driving.
     
    #16 Bitterbuffaloh, Jan 14, 2017
  17. TWOPrius

    TWOPrius Junior Member

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    Also in cold check tire pressure. Twenty drop here in Fl. Even makes a difference.

    Posted via the PriusChat mobile app.
     
    #17 TWOPrius, Jan 14, 2017
  18. Bitterbuffaloh

    Bitterbuffaloh Junior Member

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    What should it be?
     
    #18 Bitterbuffaloh, Jan 14, 2017
  19. TWOPrius

    TWOPrius Junior Member

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    Look on the tires, then the door panel pic a number between the two(･´з`･)

    Posted via the PriusChat mobile app.
     
    #19 TWOPrius, Jan 14, 2017
  20. edthefox5

    edthefox5 Senior Member

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    Multi function display it's the touch screen. Alarms show up there and or on the dash. No alarms shown no DTC logged nothing to see.

    OWNERS forum shows repair records on auth dealer in the USA.
     
    #20 edthefox5, Jan 14, 2017
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