Prius C Low economy reading, Low fuel fill up, random engine knocking...

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by ppnuwan, May 16, 2016.

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  1. ppnuwan

    ppnuwan Junior Member

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    Three
    Sold my beloved 2007 Prius to get 2012 Prius C and now I'm confused whether I've done the right thing..

    Long story short,
    I've been experiencing following issues with my new Prius C,

    1) Performance is not satisfactory (my previous car has got the same 1.5L engine and used to have a nice pick up power)
    2) Occasionally giving an engine knocking sound (only at low speeds, when taking a bend, after a break etc.)
    3) Economy shown on display is pretty bad (5.8L/100 km), after couple of fill ups I realized that it's not actually accurate..! When calculating the real figures I'm actually getting 4.6L/100 km which is way better than display shows)
    4) I tried to empty the whole tank, but after warning sign to fill the tank up, I could only fill 32L contrary to Toyota claim the tank size to be 36L

    Now what I did and assumed for above issues,

    a) All above four factors relate to the same issue.. Something wrong with fuel injectors. First I assumed the issue was with spark plugs, changed them but no difference.. Changed all four coils, still the same.. Went to Toyota dealer and straightly they suggested to clean injectors. Do you think this is the case? Anyone else had similar issue?

    b) Wrong economy display and less full tank capacity also may have been resulted by clogged injectors.. (I just assume). When I accelerate system thinks engine consumes petrol in fact it doesn't (due to clogged injectors) hence it shows higher reading but in fact the system consumes less fuel. Automatically calculating capacity with the usage it warns to fill up but in fact the tank has got plenty remaining.. Did I assume this correctly?

    Now I'm hoping to do injector cleaning myself (can't afford dealership quote) and would love to have your ideas/suggestions/advise in doing so...

    Thanks guys...
     
    #1 ppnuwan, May 16, 2016
  2. ppnuwan

    ppnuwan Junior Member

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    Three
    Just providing more info on this,
    When driving at high speeds, the car drives nice and quiet.. Performance is also much better..
    It's done only 45,000 km
    I did use fuel injector cleaners with two fill ups, issue still persists..
     
    #2 ppnuwan, May 16, 2016
  3. bisco

    bisco cookie crumbler

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    welcome! tbh, it all sounds quite normal except for the knocking. have you ran a tank of high octane through?
     
    #3 bisco, May 16, 2016
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  4. wjtracy

    wjtracy Senior Member

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    On the surface sounds like a fuel quality issue maybe leading to some gunking up of the engine. What brand are you using? and consider going to something advertised for good detergent content or add some Techron. In the US we have relatively good quality of our Regular, especially in reformulated gasoline areas, which is probably at least 50% of Prius owners. Once you get into other countries the Regular may be less well additized and may be lower quality...not sure.
     
    #4 wjtracy, May 16, 2016
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  5. ppnuwan

    ppnuwan Junior Member

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    Three
    Thanks a lot for your input guys..
    Well, I just bought the car, so I'm unable to know what the previous owner has used but I'd assume it to be the worst.. In Australia, we've got 91, 95 and 98 Octane fuel only.. (and E10 as well) So the worse (which would be 91) is still not that bad, is it? I'm by the way, only using 98 Octane..

    Another thing to add.. My second full tank, I ran even after getting 'fill tank' warning message (as I knew there's plenty left anyway) I could reach 700 km mark and then filled up the tank 35.5 L (which should be okay). This time my display shows my economy to be 6.0L/100 km but in fact it's about 5.0L/100km when you do math..! So there's definitely something wrong with the display value.

    And I've noticed, since using 98 Octane, I'm getting better performance as well (still not on par with my previous Gen II Prius which was a very special car).

    Did anyone of you owe Gen II prius before moving to Prius C and noticed the difference like I did?
     
    #5 ppnuwan, May 17, 2016
  6. wjtracy

    wjtracy Senior Member

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    Not us two but maybe some other c owners on PriusChat...but your report does not sound typical in the USA, except to say it seems to be "used" vehicles that get the most problems (just seems that way not sure).
     
    #6 wjtracy, May 17, 2016
  7. ppnuwan

    ppnuwan Junior Member

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    Thanks guys.. Will wait for someone who's in the same boat as I am..
     
    #7 ppnuwan, May 18, 2016
  8. dick_larimore

    dick_larimore Member

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    Just a few comments about your Prius C. 4.6L/100 km (61 mpg) is really good fuel economy for a C. Plugged fuel injectors would result in lower than normal fuel economy and is not consistent with what you are seeing (plugged injectors have a poor fuel spray pattern). I have driven the Gen II and Gen III Prius hatchbacks and both have better acceleration than a Prius C ( I have owned 2 Prius C vehicles). I don't know if the octane ratings on gasoline are the same between the USA and Australia. We only use 87 octane fuel and it works just fine. I have owned 5 Prius vehicles and all calculated the fuel economy about 1 or 2% over the actual, It is strange that yours comes up with a lower economy result. A Prius does have a fuel level sensor in the tank, so the car fuel readout on the dash is based on the sensor in the tank, not on calculated fuel consumption.

    I would be concerned about the engine knocking, I have never owned a Prius which had engine knocking of any kind.
     
    #8 dick_larimore, Jun 16, 2016
  9. ppnuwan

    ppnuwan Junior Member

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    Three
    Thanks a lot for your reply mate.. In Australia we've got 91, 95 and 98 Octane fuel.. I initially used 98 Octane fuel just for the sake of cleaning injectors.. It didn't seem to solve the problem. Now I'm using 91 Octane (which obviously is cheaper) and getting similar economy.. However that sound comes up sometimes.. (Not so often as you would think.. Sometimes it wouldn't come up for days.. Sometimes several times per journey.. It's really a random issue with no pattern whatsoever..) Given the nature of the issue and good fuel economy I get (and given the less than impressive performance is normal) I think this is not an issue after all.. I agree with you, engine knocking is unheard of in a Prius.. Couple of weeks ago I got the car checked by a Toyota dealer, and their proposal was to 'clean injectors' to which they gave me a price of 600$. I couldn't see that was the problem so I passed.. Anyways, still driving it with no issue (only that annoying vibration and 'knocking alike' sound occasionally)
     
    #9 ppnuwan, Jun 20, 2016
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