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Burning oil at same rate regardless of oil thickness --- What does it tell us?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by AllenZ, Dec 13, 2013.

  1. AllenZ

    AllenZ Active Member

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    Question: Sometimes the gas pedal feels 30% harder to push. Why?

    I noticed that Yesterday (27F, not as cold as last week at -10F), the gas pedal was harder to push down, and the engine also sound rougher to run (not engine knock sound), for about 15 minutes. Then everything getting normal, and then for a period, it even feels super smooth. Is it the gas pedal's mechanical issue or the engine issue? MPG remained at 42-43 range, just as normal.

    Note that I've added 20% MMO into the dino oil for about 3 weeks and has run 1600 miles. Does this has anything to do with rough engine/tough gas pedal?

    Thanks!
     
  2. Britprius

    Britprius Senior Member

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    The gas pedal is not mechanically connected to anything in the engine bay. You are only pushing against a spring as the pedal controls an electrical device that sends signals to the computer asking for more or less power. It is drive by wire.

    John (Britprius)
     
  3. jadziasman

    jadziasman Prius owner emeritus

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    Unrelated I'd say. Is something blocking the gas pedal? Check your floor mat.
     
  4. AllenZ

    AllenZ Active Member

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    Nothing on floor that will blocking the pedal.
     
  5. jadziasman

    jadziasman Prius owner emeritus

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    Then the mechanism is binding because it's 10 years old. A strange coincidence but that's the only logical answer. Do you have the service manual on pdf?
     
  6. AllenZ

    AllenZ Active Member

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    No. What is that? I have printed user manual in car.
     
  7. jadziasman

    jadziasman Prius owner emeritus

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    It's a multi-section service manual that was available for downloading a couple of years ago and maybe still is. The mods won't allow us to post pages from it on this site since it is copyright infringement but I'll look for the pedal in the service manual and try to find out what might be hanging up the pedal on your 04 and get back to you.
     
  8. jadziasman

    jadziasman Prius owner emeritus

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    The accelerator pedal rod is a one piece assembly that is shown in the P112 hybrid vehicle control section of the service manual (Page HV-566 in the 2006 model year service manual to be precise). You might be able to take it apart and find out what's binding inside of it but the service manual does not provide any details of the pedal rod's guts.

    If it's binding and the resistance you're experiencing in actuating it bothers you it seems your only option is to replace the pedal assembly with one from a junkyard.

    The pedal assembly is held to the firewall with two bolts. It looks like it wouldn't be too difficult to replace it. The manual states the 12V aux battery needs to be disconnected before disconnecting the sensor connector from the accelerator pedal rod.
     
  9. AllenZ

    AllenZ Active Member

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    The accelerator pedal has no problem these days, even at -8F degree.

    Update on oil burning:
    After adding MMO into oil and gas for 2150 miles, the burning rate comes down to roughly 1qt/1200 from 1qt/850. Still a lot of burning, but shows clear improvement.

    I plan to use MMO ($6, 32oz) for total of 6K miles, then switch to Auto-RX (I have two 12oz bottles, paid $50 total), and use that for 6K miles, with rinse cycle in between. Hopefully to draw some conclusion of which one is more effective in my case. It will take me 6 month to finish this test. I will keep you updated.

    Thanks for all the help!
     
  10. drewbabich

    drewbabich Junior Member

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    Any way to get that pdf service manual emailed to me? I want it. Those are awesome.
     
  11. CBarr31

    CBarr31 Active Member

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    Allen,

    Glad to hear you are seeing improvement with MMO. I didn't have any luck with it but as we discussed in another oil burning thread every car can be a little different. I tried Restore, Seafoam, MMO and a couple other things for the oil. Also tried Techron, Seafoam and a couple of other things with the gas. None of it slowed down the oil burn BUT none of it made it any worse except when I used a full quart of MMO because of its lower viscosity.

    Anyway, I am mentioning this because I am very familiar with "The Burn" and Ema has 364,000 miles now and it really hasn't gotten any worse in the last 60,000 miles. I'm at about 1 quart every 1,500 miles or so or I was ....

    I say I was because ... wait for it ... Ema's oil burning has shown significant improvement in the last month or two. She now is burning at only 1 quart every 2,000 miles and sometimes better right after an oil change. What is the difference? The ONLY thing I have done different is a switch to ethanol free gasoline whenever possible and when not possible I add 2 oz. of Lucas Oil Ethanol Fuel Stabilizer at fill up.

    That is really the only thing difference and not only has it made a difference with the oil burn but my MPG's have gone from 35-40 MPG with ethanol gas to 44-49 MPG with non-ethanol. That is a HUGE jump and right at Ema's lifetime MPG and at her "Summer" MPG numbers the last couple years. Not only are the MPG's better but the engine is NOTICEABLY smoother, quieter has more power, etc... etc... How do I know? Driving so much I routinely go up numerous hills here in the south and almost always use cruise control. With a scangauge I don't let Ema go above 4,000 since the burn started and there are now hills I can go up with ethanol free gas at under 4,000 RPM that I can't with ethanol gas.

    It might be something to try. I would give it at least a tank or two. I downloaded an app called Pure Gas to help me find ethanol free stations.

    Good luck and happy driving,
    Chris
     
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  12. AllenZ

    AllenZ Active Member

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    Chris,

    Thank you for tons of helpful info.

    Too bad the closest pure gas station is 50 miles away. Can't believe they wasted 30% of farmland to grow corn for ethanol, subsidized with tax dollar. Last time I was in corn field, I simply can't imagine that the energy density of the corn field will produce enough fuel needed for plant, harvest, refine and transport the corn and ethanol. With 30% more farmland, we will have lower price on food, more affordable organic food, less oil import, and less tax. Of cause that's NOT what they want.

    OK, back to Prius. The Lucas thing sounds interesting to me, although I'm not sure how it helps reduce oil consumption. I will try it while continue the MMO treatment for another 2000 miles. When the weather getting warmer, I will also try the cylinder soak with MMO.

    Due to miscalculation, my oil consumption actually improved only 10-20% on paper, not 50% as I thought before. The fact that I'm using 10W40 with MMO (vs. 5W30 before), together with very cold weather, probably means actual consumption roughly remain the same.

    However, mpg seems improved after adding 4 oz MMO to 10 gal gas. In these very cold days, I can get low 40s mpg, vs. 37 before. Today at 40F, it's 47 mpg, almost back to normal.
     
  13. CBarr31

    CBarr31 Active Member

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    Allen,

    Sorry to hear about the closest non-ethanol station being so far away. I live near Lake Norman which is a big fishing and boating lake here so lots of gas stations carry non-ethanol in various grades for the boaters. The website I use is listed below and they do have an App available, although it could be A LOT better. I wish it was like Gas Buddy with member updates and times but it is decent.

    Ethanol-free gas stations in the U.S. and Canada

    As far as seeing lower oil consumption with 10w-40, that is the one thing that slowed Ema's burning before the pure gas did so I think that may be helping more than you realize. I am interested in the "engine soak" if/when you do it because I may try that as well. I know I know everyone will say why waste the money on a such a high mileage engine why not replace it completely or replace the car completely. That actually make more sense financially but I am curious to see what may be the exact cause and if it can be fixed. Pure engineering curiosity at this point, lol.

    Anyway, I still do put about 2-3 oz of Seafoam in the last 500 miles before an oil change but have been doing that for a long time. That may have a cumulative effect on cleaning the engine but I think the pure gas is helping more. It also makes the engine run better as I noted. Your thread and the one beloew are the two main ones I follow regarding "The Burn".

    2008 Prius - burning oil at 135,000 miles | PriusChat

    Chris
     
  14. jdenenberg

    jdenenberg EE Professor

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    PM me

    JeffD
     
  15. CBarr31

    CBarr31 Active Member

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    Everyone,

    Ema passed emissions this morning!!!!! WOOT WOOT (y) :) (y) That means I have another year and 40,000 - 50,000 more miles that I can keep feeding her oil and seeing if anything affects "The Burn", lol.

    Actually from my post back in February I have more data on her diminished oil burning when using non-ethanol gas. It is down to as little as 1 quart every 2,000 miles and that is if I push her hard at times over 4,000 RPM. If I keep her below 4,000 RPM on hills I could probably do 3,000 mile OCI's and not have to add any oil at all. She would be down to the lower dimple but is certainly not burning the 1 quart every 1,500 miles she was.

    And as I mentioned before the engine sounds SOOOOO much better and smoother on pure gas. The power is better and the MPG is "summer MPG" or maybe better, lol. Ethanol sucks!!!!

    Happy driving,
    Chris
     
  16. AllenZ

    AllenZ Active Member

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    Conclusion: MMO cylinder soak did not affect oil burning. The piston rings probably have perm damage.

    My mechanics poured 32 oz of MMO into four pistons, soaked for 4 hours, clean up and start engine.

    The SMOKE!!!

    It's like the car is burning. It lasted quite a while, 15 min I guess. Not sure if I can pass the inspection next year, possible catalytic converter damage? I went a little late, only see last 5 min smoking.

    With oil burning at 1qt per 750 mi. rate for past 30K miles, the spark plug looks terrible. I'm not sure how long the new plug will last.

    The car runs good for a week, then check engine light on. With too many codes there, he cleared the code, hope it will come on again, but 2 weeks past, nothing. Very strange.

    The MMO definitely cleaned the engine quite a bit. At least the oil cap is cleaner.

    See the old plugs picture


    image.jpg
     
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  17. JC91006

    JC91006 Senior Member

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    Burn rate is still normal specs

    SM-N900P ?
     
  18. telmo744

    telmo744 HSD fanatic

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    Yaris hybrid, I suppose.
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    Yep, the piston soaks or oil ring cleaning in general are only effective at early stages of oil consumption at lets say 1qt/3000 miles. If you keep driving with stuck oil rings, they simply wear out .

    BTW, 32 oz MMO for piston soaks is way too much. I use 1 oz per cylinder at one time.

    Now, while the plugs show the expected ash from oil burning, whats wrong with the upper plug? Valve cover gasket leak?
     
  20. AllenZ

    AllenZ Active Member

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    Good question! And what will be the effect if they leak?

    Bad news again, the check engine light is on again, it shows the catalytic converter has problem. I guess my mechanic did not suck out 32 oz of MMO before he starts engine. That's why sooooo much smoke, lasted for sooooo long.

    Now what should I do? Checked some places, the new one cost $100, but one of the seller ask $50 only on ebay. Will that be ok? Somehow I can't post that ebay link here.

    I heard by law you cannot install used one, wondering why. If I keep driving, will it getting better? What will be the worst case other than emit a little bit CO gas?

    Anyway, if oil burning getting too bad, I'm ready to replace the engine. A used one only cost $5-600, plus $500 installation. Not too bad.