Prius II Surging while accelerating under WOT

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Woodchuck, Jan 4, 2014.

  1. Woodchuck

    Woodchuck Junior Member

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    Yet another surging thread... BTW, is there another word people commonly use to describe 'surging' in a vehicle? I feel like I'm not finding the results I am looking for.

    Anywho. We have owned our 07' since it was new and have performed regular maintenance per the owners manual. We are at 105,000 miles and I've noticed a subtle surging sensation when entering the highway with my foot flat on the accelerator. Looking at the MFD, I see both the engine and motor supplying power continuously during the surging sensation. When this occurs, the batteries are never "low". They always show 5-8 bars of charge. I tuned the car with factory plugs, air filter and PCV valve, but that did not help. The sensation only seems to occur at wide open throttle and is undetectable at lower acceleration or at standard highway speeds. I'm happy to ignore the issue, but am curious what might be going on...

    Uh-oh. Just reading up on Optima Yellow Top batteries and issues for Prius owners. We installed one about two years ago. Doing some of the tests mentioned online, like engine in run position, but not running yields a battery voltage of 11.9. Out of spec, I think. Engine running = 14.1v.
     
    #1 Woodchuck, Jan 4, 2014
  2. AEROENGR

    AEROENGR Junior Member

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    During the current cold weather (< 20F) in the Northeast, I noticed a slight oscillation in the engine speed of my Prius C about 15 seconds after start-up. Persisted for a few seconds (~ 3 cycles) then stopped when I stepped on the gas to pull out of my driveway. It's a complex control system. They may not have found every limit cycle that can occur in the real world.
     
    #2 AEROENGR, Jan 4, 2014
  3. edthefox5

    edthefox5 Senior Member

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    Throttle body needs cleaning and the trans fluid needs replacing. Along with the Invert coolant.
     
    #3 edthefox5, Jan 4, 2014
  4. Woodchuck

    Woodchuck Junior Member

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    Just cleaned the throttle body. Both coolant systems were flushed when the car went in for warranty work on the coolant pump, steering shaft and gas petal. The problem is still there... I think it's the crappy Optima battery failing. It shows about 11.7V when loaded up, engine off.
     
    #4 Woodchuck, Jan 6, 2014
  5. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    I don't see the 12V battery causing this problem because the inverter provides the voltage once the car is "Ready". I don't know what it could be but I wouldn't put my money on the 12V battery. I would however change the transaxle fluid.
     
    #5 usnavystgc, Jan 6, 2014
  6. Woodchuck

    Woodchuck Junior Member

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    I seem to recall it doing something similar when the OE aux battery died. The stupid Optima battery is failing regardless, so it's getting replaced one way or another. I'll be sure to report back. Btw, the transaxle fluid was changed at about 100k miles. Thanks for the reminder! I'm happy to know that the ol' Prius is all up to par for maintenance!
     
    #6 Woodchuck, Jan 6, 2014
  7. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    Good deal well, I could be wrong about the 12V causing this problem. I've been wrong before (too many times to count lol).
     
    #7 usnavystgc, Jan 6, 2014
  8. edthefox5

    edthefox5 Senior Member

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    They don't flush the Inverter coolant they just duckbill close off the hose ends and slide it out and slide it back in.
    And that has nothing to do with the ICE coolant either.

    11.7 battery won't make the car accelerate poorly. That's is either air-fuel management or ignition.If ignition it would throw a misfire under wot. You see no cel so something in air-fuel.

    What kind of oil do you use?
     
    #8 edthefox5, Jan 6, 2014
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