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Rough idle, low milage

Discussion in 'Gen 2 Prius Main Forum' started by Verylargeboots, Oct 25, 2017.

  1. Verylargeboots

    Verylargeboots New Member

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    I have a 2008 Toyota Prius Touring with 181,000 miles on it. Recently I had some issues that I thought I had resolved by changing the spark plugs out. The CEL went away for a few months, and then came back on, throwing P0300, P0302, and P0304. I changed the ignition coils for cylinder 2 and 4, and the issue abated until yesterday. It is currently throwing the same codes listed above. In addition to this, I have a rough idle on startup. Any assistance or advice would be greatly appreciated.

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    #1 Verylargeboots, Oct 25, 2017
  2. bisco

    bisco cookie crumbler

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    what the 'low mileage'?o_O
     
    #2 bisco, Oct 25, 2017
  3. fotomoto

    fotomoto Senior Member

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    A car with that many miles has had a lot of gas run through it. Have you checked the fuel side of the equation like the injectors?
     
    #3 fotomoto, Oct 25, 2017
  4. Verylargeboots

    Verylargeboots New Member

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    37.4 mpg on average. I have not looked at the injectors yet, I was hoping to figure it out before going into something more labor intensive. Would you recommended using an injector cleaner like Chevron before pulling the injectors?

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    #4 Verylargeboots, Oct 25, 2017
  5. fotomoto

    fotomoto Senior Member

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    Yes but it will most likely take a few tanks to see the full benefits.

    Other possibilities, a faulty crank or camshaft position sensor throwing off the timing.
     
    #5 fotomoto, Oct 25, 2017
  6. Verylargeboots

    Verylargeboots New Member

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    #6 Verylargeboots, Oct 25, 2017
  7. bisco

    bisco cookie crumbler

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    have you checked all the usual culprits like tires, filters, 12v, and etc.?
     
    #7 bisco, Oct 25, 2017
  8. Verylargeboots

    Verylargeboots New Member

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    Tires are good, not great. I'll change all 4 and all 4 tpms sensors in December when they get closer to needing to be changed. 12v is fine. As for the filter, other than the cabin filter, and the air filter under the hood, what else should I look for?

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    #8 Verylargeboots, Oct 25, 2017
  9. bisco

    bisco cookie crumbler

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    that's it. make sure you get good low rolling resistance tyres, and keep the pressures up.
     
    #9 bisco, Oct 25, 2017
  10. Verylargeboots

    Verylargeboots New Member

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    Awesome sauce. I'll post after a few tanks and either habe a resolution, or go back to the drawing board

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    #10 Verylargeboots, Oct 26, 2017
  11. Verylargeboots

    Verylargeboots New Member

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    Update: After 4 tanks of gas , one with the Chevron cleaner, zero problems. However, I also switched brands of gas, from Sheetz, to a Top Tier approved gas, like Valero. I actually switched brands in all my vehicles, and noticed that they all run much smoother now. Idle is no longer rough, and so far has thrown no codes

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    #11 Verylargeboots, Nov 13, 2017
  12. SpaceCityHybrids

    SpaceCityHybrids Member

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    Use Techron right before you change your oil.
     
    #12 SpaceCityHybrids, Nov 13, 2017
  13. Dxta

    Dxta Senior Member

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    I don't think those can cause those codes yo come up
     
    #13 Dxta, Nov 13, 2017
  14. Dxta

    Dxta Senior Member

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    These are what I think could cause the problem:

    1. On the fuel system side, ensure the injectors aren't clogged with carbon deposits; fuel pump pressure shouldn't be low.
    A system that's too lean in fuel supply would cause the problem, there's less fuel going to the system.
    A weak pump can also cause it.

    2. Engine side, check to ensure your valve cover gasket, isn't brittle, and letting in oil in to the plug holes, and flooding the centre electrode of the plugs. If they do, you'd have codes.

    3. Replace all the spark plugs, if they're worn already.

    4. After you've done all that, and the problem persist, have the electrical circuitry on the number two, and four replaced.

    5. A dead or failing injector system, would cause the problem you make o
     
    #14 Dxta, Nov 13, 2017
  15. Hoho

    Hoho New Member

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    So do you believe that it was the gas that caused it? I just do not understand how gas goes bad - I presume that there is pretty high QC with refineries. But then again, I have definitely gotten a tank of gas somewhere, had CEL come on and the car ran rough until the next station, filled up and then everything was fine.
     
    #15 Hoho, Nov 13, 2017
  16. Verylargeboots

    Verylargeboots New Member

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    Hoho: I have no idea if this is the reason, to be honest. However, I still have no codes thrown, and none stored since switching brands. This is my assumption since other than the aforementioned maintenance, nothing else has been done to the vehicle. I do know that the gas is mixed with ethanol at the station, and that may have something to do with it.

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    #16 Verylargeboots, Nov 15, 2017
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