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Diagnosing Prius Issues

Discussion in 'Newbie Forum' started by sc008y, Jun 10, 2019.

  1. sc008y

    sc008y New Member

    Joined:
    May 4, 2019
    7
    1
    0
    Location:
    Lehigh Valley, PA
    Vehicle:
    2006 Prius
    Model:
    Two

    So I bought a 200k 2006 Prius with a 3yr old traction battery for and a decent price. Although it had a very mild lifter tick, my intent was to keep it going as long as possible, mostly as a challenge, but I'm running thin. I did a general tune up (spark plugs, fuel injectors, oil, transaxle fluid, etc.) I averaged about 45-50mpg after buying it.

    My first point of concern was raised after a mild trip, the morning after the lift tick was noticeably noisier. I just passed it by and did nothing about it.
    Time goes on and another longer trip again leave the lifter ticking even louder. Another point to note is now the fuel economy is slightly dropping.. Roughly 40mpg now.

    Now the final straw. I take it for another trip and already I'm noticing terrible fuel economy. 25-30mpg. Soon after the CEL comes on. I have TorquePro so I discover its the downstream 02 sensor. I continue the trip with terrible fuel economy, engine and battery struggling very much. Oh, and worse lifter tick.

    I replace both 02 sensors for good measure and the code is gone but the fuel economy has stayed. I attributed part of the poor fuel economy to a bad 12v and replaced it but absolutely no difference. I parked the car for 2 months and haven't touched it.

    I feel at a loss here. The hybrid battery will not fully charge but the scanner readings don't show any abnormal numbers or cells. The car feels like it's struggling to do anything. I'd love to keep the car running and in good health but I'm not sure where to start. I can read all the codes and engine statistics, but nothing is waving and red flags. I'm planning to do a valve check because of how noisy the lifter is but even if that's bad, a valve adjustment isn't going to happen.

    I'd love to know what sensors and readings would give a hint as to what's going on because I'm clueless here.

    Thank you.
     
    #1 sc008y, Jun 10, 2019
  2. exstudent

    exstudent Senior Member

    Joined:
    Jul 11, 2009
    2,212
    900
    0
    Location:
    Torrance, CA
    Vehicle:
    2007 Prius
    That 3yr old HV Battery is NOT 3yrs old but WAY OLDER. Pop the cover off the HV Battery case. The serial numbers will not be sequential, indicating it is a typical Frankenstein used battery (AKA: remanufactured/reconditioned/rebuilt) assembled using an assortment of modules to make a working (albeit temporary) pack.

    Start preparing for a repair or replacement. New OEM HV Battery is your best bet for a long, trouble free operation; lowest price reported so far was $1600. Then their is 2k1Toaster's cylindrical module replacement alternative, if you can not get a dealer to sell to you cheaply.
     
    #2 exstudent, Jun 11, 2019
  3. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,097
    5,810
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    Let's look at symptoms first before we go jumping off the deep end. Does your torque app provide upper and lower O2 sensor readings (upper is actually called air/fuel ratio sensor, but it doesn't really matter)?

    Before throwing away a ton of money, I would buy a $150 catalytic converter pipe from ebay and replace the exhaust system from the exhaust manifold to the muffler.

    Fits 2004 2005 2006 2007 2008 2009 Toyota Prius 1.5L V4 Catalytic Converter | eBay

    A weak HV battery is not likely going to drop mpg to the 25-30 mpg range without having thrown a code. A plugged cat will create havoc with mpg and engine power. The ticking noise you hear that is getting louder and louder could also be an exhaust leak getting worse due to backpressure.

    You just cut your exhaust between the second cat and the muffler, unscrew the O2 sensor from between the 2 cats, unbolt the cat assembly from the manifold and install the new one. The kit includes new fasteners and springs for the manifold connection. The other end is expanded so it can slip over the muffler pipe after you cut it. The donut gasket included with this kit is a bit on the cheap side. I would recommend getting an OEM donut.

    After that's done, and if you're satisfied, you can sell the old OEM cats to one of our members. I'm sure he's still purchasing them @ $300 a set. I'll find his user name and get it on here later.

    Since I'm not standing next to you, I'm not going to tell you that I know what you have in your car. If you're curious about the origins of your HV battery, post the serial number from the sticker on the outer case (or even better, post a photo of it). From that, we can at least tell you if it's a replacement Toyota battery, or an older case that was probably a rebuild. If you're really curious, post a photo of the top of the modules showing the serial numbers printed on them. We can provide even more information.
     
    #3 TMR-JWAP, Jun 11, 2019
    Skibob and Raytheeagle like this.
  4. sc008y

    sc008y New Member

    Joined:
    May 4, 2019
    7
    1
    0
    Location:
    Lehigh Valley, PA
    Vehicle:
    2006 Prius
    Model:
    Two
    You are correct, it is a Dorman remanufactured battery. I have to look into the warranty to see if it is owner transferable, and if it has nay time left on it before cracking the case open. I have been monitoring the battery with TorquePro and I haven't really noticed any odd behavior.. What should I be looking for?
     
    #4 sc008y, Jun 12, 2019
  5. sc008y

    sc008y New Member

    Joined:
    May 4, 2019
    7
    1
    0
    Location:
    Lehigh Valley, PA
    Vehicle:
    2006 Prius
    Model:
    Two
    I took the Prius on my commute and logged some of the data. For some reason I can't get any more than the temp from the downstream O2... I might be overlooking something. But, I have that along with some other runtime data in a spreadsheet here:



    I noted the min and max values at the top for easy access.

    When I replaced the O2 sensors, I did pull the exhaust and get a visual on the cat, which looked clean and intact, however I'm not too familiar with clogs and I'm assuming it can get clogged further inside? I can pull it again and try the guitar string test or something similar to find out if its clogged.

    As for the noise, I'm fairly certain its a lifter. I videoed it. It sounds very metallic and is definitely more audible at the valve cover.
    Here is the video:



    Regarding the battery, it is a Dorman remanufactured battery. I have to look into the warranty before cracking the case to see if its transferable between owners, and how much time it has left, if any. I attached a picture of the label.
     

    Attached Files:

    #5 sc008y, Jun 12, 2019
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