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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. SWprius08

    SWprius08 SoCalprius

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    I already cleaned the MAF sensor myself, I had posted before and after pictures a few posts ago on this same thread
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Have you checked the ETCS fuse? That is the first step. which got lost from my prior post. Use an ohmmeter to verify its condition, do not rely upon visual inspection.

    If the fuse is good, and if you are comfortable that no other DTC exist, then the problem is either the throttle assembly or the engine ECU. If you lack this comfort then get Mini VCI now.

    When you are looking for a used throttle assembly, obviously you want one that shows no signs of physical damage. Beyond that, you need to install it to determine its functionality.
     
    #62 Patrick Wong, Dec 22, 2014
    Last edited: Dec 22, 2014
  3. Yakoma

    Yakoma Active Member

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    Missed that...sorry
     
  4. SWprius08

    SWprius08 SoCalprius

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    Thanks for direction and continuous support Patrick. Would be what you are asking me to get? It does not seem to be available in US, only from China. I can still get it.
     
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    This is the one that I bought, it is manufactured in China but fulfilled by Amazon in the US so you shouldn't have an extended wait.

     
  6. SWprius08

    SWprius08 SoCalprius

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    Thanks I will go ahead and get this one. One good thing has happened after the diagnostics on Saturday, the car is running better and better, mornings were always very rough but today it seemed much better. I also pressed complete throttle for a few seconds and it seemed like I was bale to get the power better then what I did 2 days ago, not sure if cutting the fuel line to test the fuel pressure did something, like released the air or something). Hopefully this just gets better and better and becomes normal so I wont have to perform the expensive repair. Will post update if things change.
     
  7. goldfinger

    goldfinger Active Member

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    What's a little over max to you? Dealers have been known to overfill. Too much oil can cause engine trouble. Post a picture of your fill level.
     
  8. SWprius08

    SWprius08 SoCalprius

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    CAM01711.jpg
    Here it is.
     
  9. goldfinger

    goldfinger Active Member

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    That doesn't look too excessive.
     
    SWprius08 likes this.
  10. SWprius08

    SWprius08 SoCalprius

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    Patrick,
    Would it be worth trying to remove the throttle body, disassemble, clean, reassemble and re-install? I found this page that does exactly that. Let me know if it worth doing this.
    TB cleaning
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My post #62 above asked whether you had checked the ETCS fuse. Have you done so?

    You have nothing to lose by following Hobbit's page since you are planning to replace the throttle body assembly anyway.

    I suggest you wait until you receive Mini VCI so that you can confirm the throttle opening readings taken by the Meineke tech per your post #57. Then after cleaning the throttle position sensor, see if there is any change to the readings.
     
    #71 Patrick Wong, Dec 23, 2014
    Last edited: Dec 23, 2014
  12. SWprius08

    SWprius08 SoCalprius

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    No I have not, I am waiting for the Mini VCI as along with that I also ordered a multimeter.
     
  13. SWprius08

    SWprius08 SoCalprius

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    finally received the mini VCI and multimeter, I removed the ETCS fuse (10A) and checked for continuity and it sounded very solid, I also tried checking for resistance but the numbers kept fluctuating from 10 to 1500, in order to make sure if this behavior is normal I checked resistance on a brand new 10 A fuse as well (which was slightly bigger) and got the same result of fluctuating numbers, not sure if this is normal, this is all too new for me. Anyhow so based on my observation the fuse seemed OK

    I have not got a chance to check the throttle position by manually opening the opening the valve fully, however the software had a couple of tests that I can perform where I could open or close the valve fully and then check the readings, when on close the "Throttle Sensor position" shows 0%, however then open it shows 32.9%, not sure if anything can be concluded from this (see attached picture), while doing this test the car was on by pressing the power button 2 times without pressing the brake pedal. However I will try to open it by hand tomorrow morning and then check the reading.
    CAM01735.jpg
     
  14. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I don't know why the ohmmeter reading would fluctuate so much unless there is a problem with the test leads. Try to press hard on the fuse contacts with the test probes, when you measure resistance. Also, to further verify the proper functioning of the multimeter, use the voltmeter function to measure voltage, for example a new 9V battery should measure ~9.6V. Then measure the Prius battery voltage from the dedicated positive jumpstart terminal to body ground (for example, a front strut mounting nut), when the car is IG-OFF. What reading do you get?

    In any event it sounds like the ETCS fuse is OK.

    A good idea to open the throttle by hand to see what the reading is. Hopefully you can place the laptop where it can be seen by you, or hook up an external monitor with a sufficiently long video cable, or else you may need a helper to assist.
     
  15. SWprius08

    SWprius08 SoCalprius

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    I had found the below current DTC's on the laptop after connecting the mini vci when I performed a "Health Check", I cleared these and after some time re ran the health check and they did not appear again, it has been couple of days of driving I will check it again today to see if these DTC's re-appear. These have never showed up on my car's screen.

    1) ABS/VSC/TRAC - C1300
    2) Air Conditioner - B1421
    CAM01737.jpg

    Update: After couple of days the C1300 still did not come up.
     
    #75 SWprius08, Jan 5, 2015
    Last edited: Jan 6, 2015
  16. valde3

    valde3 Senior Member

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  17. SWprius08

    SWprius08 SoCalprius

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    Based on the instructions of this page Toyota Prius: How to Clean the Throttle Body - PriusDIY.com I tried opening the throttle plate by hand while having a live monitor, however the plate did not move, the black knob felt very tight but I was able to rotate it counter clockwise about 90 degree and held it in place for few seconds but the plate did not move (car was on by pressing on/off switch 2 times without pressing brake), is this normal? See the picture of the knob and upto the position I moved.
    Manual Open of Throttle Plate.jpg
    After this I performed the same test again of opening/closing the throttle from the software, it again reported 32.9 % open and at this position the throttle opening looked like this (again car was on by pressing on/off switch 2 times without pressing brake),
    Throttle Open.jpg

    Not sure I did not do something correctly to open the throttle plate by hand.
     
  18. SWprius08

    SWprius08 SoCalprius

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    Apart from manually trying to open the throttle plate I also performed some more tests and I found some interesting results.

    1) When the car is cold the engine hesitates and produces (what sounds like) a misfire. This was recorded in the health check, this did not happen after the engine was warm after sometime when I ran the health check again, it did not hesitate much either (but it did slightly).
    Engine ECT Misfire.jpg

    2) Found a "Blad Tank Leak" failing as the test result was 0 under "Evaporative System"
    Blad Tank Leak.jpg

    3) When in parked position if the gas pedal fully depressed the engine only revs till 2500 RPM, is this normal? I find it low? Below are 2 pictures, one of the live screen when the foot is off the gas pedal and another then the gas pedal is depressed completely.
    Gas Pedal - Foot Off P.jpg Gas Pedal - Completely Depressed P.jpg

    What can be concluded from these findings?
     
  19. valde3

    valde3 Senior Member

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    Only couple of misfires with cold engine doesn’t seem that bad. Maybe test it again to see if it misfires on those same cylinders. If it does you could change cops (coil on plug) around and see if misfiring cylinder moves. If it doesn’t that indicates spark plug, fuel injector, wiring or mechanical problems.

    I think 2500rpm is normal limit at park.
     
  20. SWprius08

    SWprius08 SoCalprius

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    I have been checking this and found that every time the car is parked for couple hours at the initial startup there will be misfires. How would I know which cylinder is misfiring?