Fuel Injection/Throttle Body Troubleshooting

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Lean on me, Apr 18, 2023.

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  1. Lean on me

    Lean on me New Member

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    Greetings, I am new here. I drive a 2nd Gen Prius, whom I named Madam Gray. I recently cleaned the fuel injection thottle body valve along with the sensor. I decided to simply remove the unit to carry out this operation. The tools of choice were a microfiber cloth, soft bristle tooth brush, and brake cleaner for the valve. I decided to allow the sensor to soak in electronic cleaner. After the initial cleaning, I used an air duster to remove any excess cleaner fluid and allowed the parts to dry for 24 hours. The following day, I reassembled and installed parts. I then proceeded to placed her in service mode and listen. I noticed unsteady idling which prompted me to take a closer look. What I observed was the motor that controls the valve is not actuating. It does, however open about an eighth of an inch upon starting. Aside from that, it simply remains closed despite depressing the accelerator pedal. I am, however, able to manuallly turn the valve while she is isn't running. This leads me to pose three questions. However, depending on the answer provided for the second question, a response may be unnecessary for the third question but I will include it.

    1. Does the Prius have the ability to operate under a rich air-fuel ratio?

    2. Will a new throttle position sensor restore functionality of the throttle body motor?

    3. Does the fuel injection throttle body system need replacing?

    Side note: I am mechanically inclined. I also have quite a bit of time on my hands. All responses are welcome. Thank you in advance.
     
    #1 Lean on me, Apr 18, 2023
  2. bisco

    bisco cookie crumbler

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    probably
     
    #2 bisco, Apr 19, 2023
  3. ChapmanF

    ChapmanF Senior Member

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    Can you clarify which sensor you mean here? The position sensor included with the throttle body?

    Were you having any symptoms that led you to think the sensor ought to be removed and soaked in contact cleaner?

    Did you check the repair manual to see if it describes any procedure for separating the sensor from the throttle body, or for calibrating it on reassembly, or recommends against doing so?

    Toyota Service Information and Where To Find It | PriusChat

    Do you have any warning lights on the dash? Do you have a scan tool?
     
    #3 ChapmanF, Apr 19, 2023
  4. Tombukt2

    Tombukt2 Senior Member

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    Even with the bad idling does the car drive like off idle progressions days and driving do you have that capability or is everything all over the place. Was the car driving badly or was this just an exercise because you're thought it needed to be done or what's happening usually people don't really rip these electrics throttle bodies off too tough they just clean them out swab them out put them back in service sometimes when people are fooling with these they're already starting to go bad the motor doesn't work in them whatever something stuck.
     
    #4 Tombukt2, Apr 19, 2023
  5. Lean on me

    Lean on me New Member

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    Thank you for the response.

    To provide context, I have been troubleshooting this issues for several weeks now. Aside from test driving the vehicle under load, I haven't driven the vehicle regularly not since the symptoms first appeared. The test drives are conducted on county and city roads with travel being no more than 2 miles. Currently, the warning lights will display before I hit the 2 mile mark. I have not driven the vehicle any further than a couple of miles because I know the air-fuel ratio is unbalanced. In this scenario, the fuel mixture is rich due the valve remaining closed.

    Fuel - Air = Poor performance/engine stall

    These symptoms include rough idling, delayed acceleration, reduced fuel efficiency, and upon inspection of the throttle position sensor which is located within the air filter box via a hole adjacent to the throttle body motor were visibly covered in, I assume, a mixture of plastic particles and carbon deposits. The platinum rod and the the two capacitors were totally covered in the stuff. The TPS is attached to the TB via screws. Dashbody lights include master warning, check engine, vsc, and the "(!)" sign located on the MFD. I haven't received any DTC codes regarding the powertrain using an Innova 5160RS scan reader tool. It isn't quite as thorough as the Toyota Techstream software but I have been able to read and clear codes, and view live data. Although I had removed and the clean the TB system comprising of the Air Filter box and TB motor unit itself, I had not fully disassemble the TB motor unit. I will be reexamining the initial cleaning and will then proceed with dissembling the motor unit to inspect the wires, contacts, gears, and whatever else is tucked inside of the motor unit housing. I will provide an update soon.
     
    #5 Lean on me, Apr 19, 2023
  6. ChapmanF

    ChapmanF Senior Member

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    For clarity, would you be able to attach photos of the items you mean here?

    With the lights you have, there are definitely powertrain codes that the scan tool you are using is not showing you. It might be worth pursuing some way to read those.

    Any code behind the VSC light you can always read using the blink method, whether or not you have a suitable scan tool.

    Blink (a/k/a Flash) Codes – How to. | PriusChat
     
    #6 ChapmanF, Apr 19, 2023
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  7. dolj

    dolj Senior Member

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    The part you are describing sounds like the air temperature sensor that is incorporated into the Mass Air Flow sensor normally referred to as a unit as the MAFS or MAF sensor. The actual airflow sensor is inside the body towards the center of the unit.

    The actual throttle body position sensor is integrated with the throttle body motor.

    So, yes a picture will be really helpful so we can avoid the guesswork.

    I wouldn't if I was you, this is not a field serviceable part, and you will have no way to calibrate it on reassembly.
     
    #7 dolj, Apr 20, 2023
  8. Lean on me

    Lean on me New Member

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    Greetings, I was able to pull a couple of hidden codes. The codes are as follows: 1259 - HV System Regeneration Malfunction
    1310 - Malfunction in HV System

    It appears as though the shop manual is implying users test for voltage of the IGN2 relay? I'm not sure how to proceed. Any input from members is much appreciated.
     

    Attached Files:

    #8 Lean on me, Apr 27, 2023
  9. ChapmanF

    ChapmanF Senior Member

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    There's nothing about C1259 and C1310 that would make me call them "hidden". They are both from the ECU that controls braking and skid control, and they're why your ((!)) brake warning and skiddy-car stability control warning lights are on. (If those lights aren't on with those codes current, there's a dash display problem.)

    That ECU has three functional areas: electronically controlled braking, ABS, and stability/traction. While the ECB control is what says C1259, and the traction control is what says C1310, the two codes mean essentially the same thing.

    Both of those functional areas have to cooperate with the HV control ECU (kind of the orchestra conductor for the car). When braking, the two ECUs collaborate to make regen happen. The skid ECU says "hey, HV ECU, driver wants to brake this hard", the HV control ECU says "I can do this much with the transmission for regen", and the skid ECU says "great, I'll do the rest with the brakes".

    When there's a traction event, the skid ECU can talk to the HV control ECU to request either a reduction or an increase of power. (If wheels are spinning, it can apply braking on individual wheels and/or request less power. If the car has locked a wheel and is skidding, it can request a little burst of power from the HV ECU to kick the wheel back up to the speed of the car.)

    These trouble codes mean that the HV control ECU has detected some kind of problem, set some trouble code(s) of its own, and notified the skid ECU. If the HV ECU has said "hey, don't count on me for regen", the skid ECU will set C1259 and not try to do regen. If the HV ECU has said "hey, don't count on me for fancy traction stuff", the skid ECU will set C1310 and not try to do fancy traction stuff.

    So neither of those codes tells you about any real problem with the braking system, only that you should go find out whatever trouble code(s) the HV control ECU and battery ECU might be showing. Those will usually be P (powertrain) codes.

    Some scan tools will not show codes from the HV control or battery ECUs. If you have a scan tool that shows you C1259 or C1310 but doesn't show you any HV control codes, it'll take a better scan tool to find out what's really going on.
     
    #9 ChapmanF, Apr 27, 2023
  10. Lean on me

    Lean on me New Member

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    Thank you for the response. I was able to pull those DTC codes using a Innova 5610 CarScan Tool. Surprisingly, the code reader did not detect a single code regarding the powertrain. Is there a standard of code reader scan tools the members reccomend? Thanks
     
    #10 Lean on me, Apr 28, 2023
  11. ChapmanF

    ChapmanF Senior Member

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    A person who wants no messing around and just to get the job done will use Toyota Techstream on a Windows laptop, same as the dealers would. There are countless threads around here about that.

    Beyond that, here is a thread that reviews a number of other alternatives, with information on which ones are better at retrieving all the codes in a Prius:

    Gen2 OBD2 app review | PriusChat
     
    #11 ChapmanF, Apr 28, 2023
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