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High RPM loss of power, fluttering noise from ICE

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by 200Volts, Jan 20, 2014.

  1. 200Volts

    200Volts Member

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    With only 356k miles on my 06, I'm now getting a sudden drop/loss of power at high RPM. At about 80mph on flat land (or about 60mph up hill) if I try to accelerate the power drops off as a fluttering sound starts (not engine knock). The fluttering sounds like 6 inches of celophane tape flapping in the wind at highway speeds.
    I just cleaned my K&N air filter, but the plugs, injectors and fuel pump are original. I ran 1 can of injector cleaner (SeaFoam from O'Reilly) with little to no improvement. I'm guessing it's the fuel pump/pressure, since it runs fine at lower RPM, with no loss of mpg or power (still 50mpg average). I know the fuel pump is in the tank ($400 in parts alone). I'll see if I can measure the rail pressure with Torque and my CANBUS scanner.
    Any other ideas would be appreciated.
    ===== dealer diagnosis eventually said clogged catalytic converter =====
     
  2. northwichita

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    If your spark plugs are really original, that must have set a record. Suggest changing them, think 120k is the norm.
    If this has already been done , suggest cleaning the mass air flow sensor.
    Also, congrats on the high mileage, you are doing some things right....
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My idea is to inspect the engine air intake from its entrance which faces the windshield washer reservoir, to the air cleaner housing. Open up the housing and look into the hose that leads to the resonator located in the right front wheel well. Any obstructions?

    Further I agree that all maintenance that had been deferred as per the 100K and 120K mile service schedule should be performed now.
     
  4. bisco

    bisco cookie crumbler

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    only 356, 000 miles and your already having trouble? what a hunk of junk.:mad:
     
  5. vskid3

    vskid3 Active Member

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    How does it do under hard acceleration at lower speeds? Kind of sounds like what a guy with an Escape Hybrid was experiencing when his cat clogged up, but he could only make it to about 40MPH before it would power out.
     
  6. rwyckoff

    rwyckoff Phev's Plus Home Solar power1

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    My plugs were starting to shoot out the side of the plug after 100k miles, can't imagine what yours are doing at 356k.
     
  7. 200Volts

    200Volts Member

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    Oh yes, I have the yellow warning light for the catalyst ratio being wrong (P0240 ?). I believe that is either a bad cat, or one of the o2 sensors. I just ran the Torque scan again, with no other codes showing.
    Yes, from a dead stop, if I press the accelerator past about 90% I get the same effect. I can't find a PID for the fuel pressure, but do have the air fuel ratio. I'll look at this on my long uphill run tomorrow (1,000 feet in about 10 miles). I'm guessing it's running lean, since their is no backfires, loud noises like I've seen elsewhere in rich conditions.
    Yes, original plugs.
    I cleaned the MAF about 50k ago and will repeat. I just replaced HID bulbs, and did not notice any obstructions in the air intake snorkel/box.
    Did I mention the original shocks??? I could autocross this thing it rides so stiff.
     
  8. vskid3

    vskid3 Active Member

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    Here is the link to the Escape with the clogged cat. Watch the videos he posted and see how they compare to your Prius. I would bet that this is your problem.
     
  9. Joe 26

    Joe 26 Member

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    I agree, fuel pump weak under load or clogged catalyst, that's where I'd look first.
     
  10. 200Volts

    200Volts Member

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    Looking at Torque: 70mph cruise is pulling 120 cfm air intake. Pushing throttle down 90% at loss of power then shows about 290 cfm air intake - so I'm guessing it's not a clogged cat, because it looks like air is flowing.
    However, looking at the air fuel ratio - MEASURED under high throttle, this is swinging wildly from about 13:1 to about 16:1 - with a calculated steady 14.7:1. So the ECU is chasing something...
    Also, looking at the cat temps, the #1 probe stays steady about 1100F, under 70mph steady the #2 probe is about 850F (but then drops about 30F under 90% throttle - lean ???)
    My guess is the plugs or lack of fuel flow.
    --- Does anyone have a PID for the fuel pressure, or fuel rail pressure ??????
    Torque screen shots are attached: (if you have a Galaxy S3 or S4, you can take a screen shot by swiping the side of your hand across the screen at any time - if this option is turned on in "settings").
     

    Attached Files:

  11. FreydNot

    FreydNot Member

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    You can also press the home and right side single button at the same time to trigger a screen grab. Sometimes this method is better since you don't accidentally make Torque scroll to the next page.
     
  12. 200Volts

    200Volts Member

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    Spark plugs were replaced at 358,400 miles. They were dry, mostly there, with a thick, light-brown/white crust all over - except the anode tip. PC won't let me upload a photo for some reason.
    No improvement in Loss of Power/Fluttering issue. A little less detonation on acceleration.

    Recent Observations:
    If I stop for 2 minutes, then acceleration is normal, even at 3/4 throttle, up to about 60mph.
    But if I'm cruizing at 50mph, then try to accelerate even moderately, I get the loss of power / fluttering noise.
    Now, on long uphills, I get a surging every 2 seconds, when close to the losss of power (lack of fuel ???).
    Gas mileage plummeted from 50mpg to about 42mpg before the plugs were changed.

    I'm going to have Toyota diagnose. I'm guessing low fuel pressure due to clogged filter, or weak fuel pump, or clogged injectors. $400 part (plus labor) for a new tank/filter/pump plus labor will be painfull (if this is needed I'll try for a used one at about $125).
    IF ANYONE KNOWS HOW TO MEASURE THE RAIL FUEL PRESSURE, PLEASE LET ME KNOW. I use Torque for CANBUS info, but can't find the formula for fuel pressure.
     
  13. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I hope that you have already checked your engine air filter and the ducting that leads up to it.

    It is a good idea to seek professional help now.

    I am not aware of any electronic means to measure fuel rail pressure. It is necessary to actually hook a pressure gauge onto the rail.
     
  14. 200Volts

    200Volts Member

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    Yes, intake system is open and cleaned MAF. Torque shows 120cfm airflow intake at cruize, then about 290cfm at 3/4 throttle. So I think air is flowing, which would also lead me to the cat being OK, .... I think.
     
  15. vskid3

    vskid3 Active Member

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  16. 200Volts

    200Volts Member

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    So on a whim, I tried PREMIUM gas last night. This helped reduce the fluttering for about 50 miles, and then it came back. Since I'm all over the map with ideas - could the knock sensor be cutting off fuel flow ?
    I'm at the dealer now, $150 for just the diagnosis...:(
     
  17. 200Volts

    200Volts Member

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    The dealer says : Clogged Catalytic Converter, please pay $2,200 parts and labor. I'm exploring other options.
     
  18. 200Volts

    200Volts Member

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    I found a salvaged cat/pipe, 53k miles, for $600. Had a local shop install for $80.
    Old cat was about 50% plugged with tiny black spots covering holes (sorry , no photo).
    Cleared the P0420 code, runs great!

    Post Mortem, signs that indicate clogging cat:
    Engine Check light, P0420 came on about 3 months ago.
    Loss of power/sputtering at high RPM/or high load, with this getting worse and worse (i.e. lower RPM limit).

    The second 02 sensor was showing swings from about 2.0 to 3.2 to about 4.
    Spark plugs replaced, no big improvement.
    I tried Sea Foam and Cat-a-Clean, with no significant improvement.

    Confusing signals to me:
    MAF seemed OK (80cfm cruize, then up to almost 300cfm on high throttle). I think this fooled me as it was short term, since with would take a few seconds for the backpressure to build in the exhaust.
     
  19. uart

    uart Senior Member

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    Thanks for updating us on the cause of the problem and the details of the fix. (y)
     
    Kstoner likes this.
  20. Jon Merlino

    Jon Merlino New Member

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    I have a 2006 Prius with only 185K and I am experiencing the same problems. During an oil change at Valvoline they plugged in the computer and said the error was cat convert. I like most people just let it go because who has 2+K to throw into a 11 year old car. I was wondering, I am pretty handy and mechanical, so if I cut out the old cat converter and replace with a new one, theoretically should be a fix right? I don't see why i should have t replace the whole length of pipe? Suggestions are welcomed.