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2008 Prius losing power - Need troubleshooting help.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SWprius08, Nov 25, 2014.

  1. nh7o

    nh7o Off grid since 1980

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    That is normal behavior. It is a very good idea to allow the car to warm up before driving. That will minimize the hit to the HV battery, which may be getting weak in your case. Before the engine warms to the minimum operating temperature, there is increased reliance on the electric motors so as to minimize emissions.
     
    #101 nh7o, Jan 26, 2015
    Last edited: Jan 26, 2015
  2. sorka

    sorka Active Member

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    Odd, I've never noticed this in 186K miles of driving a Prius. I never let the car warm up. I start out immediately so the engine gets warm as soon as possible which minimizes emissions. I've never noticed the battery draining or more assistance from the MG2 during warmup staging. That said, I don't floor it or drive it hard until it is warm but I do go immediately.
     
  3. SWprius08

    SWprius08 SoCalprius

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    Is there a way to check the health of the HV battery?
     
  4. dolj

    dolj Senior Member

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    Agree 100%. Stage 1 lasts about 50 secs, so ties in with op's observation.

    It is not necessary to wait for the ICE warm up to take place, but if the HV battery is low or becoming weak, it is advisable as it will place less stress on the HV battery. Also, it is not that it requires "more assistance from the MG2 during warmup", rather that during stage 1 the motive power is exclusively electric. So, if your HV battery is weak or low, it is going to be more noticeable.

    I dare say your normal driving MO (and possibly good HV battery) means that you are less likely to notice the stage 1/stage 2 warm up phases.
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I hooked up my Mini VCI to my 2004 and read engine ECU parameters. It shows voltages produced by the various sensors, it does not show % opening. Maybe my Techstream version is different than yours, I have an 8.10 version.

    I agree with the other respondents that the remaining issues you noted are reasonably normal behavior and may be associated with a marginal traction battery. Try to avoid rapid acceleration until the engine has warmed up because the traction battery is drained heavily while the engine is in warm-up mode.

    So just drive and enjoy your car, as it appears the failed throttle body assembly was the root cause of the problems.
     
  6. SWprius08

    SWprius08 SoCalprius

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    I checked it on Friday and found no difference in the 2 acc pedal positions at all, not even a decimal change. I found this interesting article where the writer is claiming that he was able to adjust the throttle position sensor using techstream. Wondering how can one do this? What V9.30.002 MINI VCI for Toyota TIS Techstream can do? | OBD365.com Official Blog
     
  7. SWprius08

    SWprius08 SoCalprius

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    So since the problem was not completely gone, I went ahead and changed the 4 injectors yesterday and the results are encouraging. The ride is more smooth, less vibrations, better power, lower engine sound. The misfire during cold start up still there. I did find one of the injectors with gunk in it, most likely was the problem and which would get temporarily fixed with injector cleaner in the tank, still have some so will find out when I have the next tank of Chevron with no cleaner. I always used Arco, not sure if Arco did this, but have decided to use Chevron only.

    One unusual thing has started happening, the first time when I replaced the throttle body, this happened a couple of times, upon stopping the car on a light or stop the engine would suddenly rev up high as if the gas pedal got depressed, my foot would be on brakes, I got surprised, since yesterday this is happening almost every time when I slow down to stop. Is the car relearning the pedal movement?

    Here are the pictures of the interior of the injectors.
    All.jpg
    Here are some more images of the bad one only.
    1 bad 2.JPG

    1 bad 3.JPG

    1 bad 4.JPG
     
    #107 SWprius08, Feb 9, 2015
    Last edited: Feb 9, 2015
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Are any misfire DTC being logged? Any code with P030x where x = the cylinder number of the misfiring cylinder?

    If no, is it possible that the engine is just running a little rough due to having logged 90K miles and loosened clearances between moving parts in the cold, but once the engine warms up the clearances tighten up so that the engine runs OK?
     
  9. SWprius08

    SWprius08 SoCalprius

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    Yup no DTC's are being logged. Just because it is known that the coils go bad in prius I will change all 4 next week to see if that goes away, if not I will leave it at that. Until now I am satitsfied to an extent as I was able to catch 2 problems and resolved those. One being sticking throttle body and another being one clogged injector.
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Going back to your OP, how much of the engine low power driveability issue remains after replacing the throttle body and the fuel injectors?
     
  11. SWprius08

    SWprius08 SoCalprius

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    Maybe about 25% still remains, I would dedicate a portion of it to the heavier softer tires that I have (Michelin Defender 205/60/15, already broken in at 5K miles now). I feel like blaming the misfires to the remaining portion, some times I have also noticed the misfires when the car is driven although less compared to when it is cold.
     
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The engine ECU will tolerate ~25% misfire rate before logging a P030x DTC code for a particular cylinder. I don't have a high level of confidence that replacing the spark igniters will help, but it won't hurt.
     
  13. SWprius08

    SWprius08 SoCalprius

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    That is exactly what Avi said, btw I met him last weekend and he was speaking highly about you. I will still go ahead and try doing that especially knowing it wont hurt. I got a set of 4 oem, new bulk packaged coils for $140.
     
  14. SWprius08

    SWprius08 SoCalprius

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    OK so you were right. Replacing the coils did not stop the misfires however the drive got a little better, just a tiny bit. I have always used regular oil for oil changes should I change it to synthetic at this age (92K), once I had asked a Toyota advisor and he strongly advised against, stating that at this age the engine is already broken in with the regular oil, changing to synthetic might cause harm to the engine, is there any truth in this?
     
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The main concern that I would have is that the engine oil seals might start to leak if exposed to synthetic oil, after so much time exposed only to mineral oil.
     
    SWprius08 likes this.
  16. SWprius08

    SWprius08 SoCalprius

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    OK so finally the root issue was found and fixed .. Thank God!. Tell you what, these new cars are reducing the smartness of humans as most of the mechanics I showed my car to said there was no issue as no code is coming up, now finally about 3 months (in July 2017) ago that code came it and it was "P0420 - Powertrain Catalyst System Efficiency Below Threshold (Bank 1)", also thank God I am California, the catalytic converter was under warranty until 150 K miles, I had 120 K. Once they replaced it and after running couple tanks my car is very close to normal. The first time I noticed the issue was around 75 K miles, so it ran under this condition for around 45K miles and I believe it has caused a permanent damage of approx. 5% to the engine etc. I have the power back, gas mileage is right there. Thank you all for your inputs.
     
    Joeman200 likes this.