2005 red triangle unless maf unplugged then check engine only

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mech1222, May 5, 2022.

  1. mech1222

    mech1222 Junior Member

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    2005 new to me.

    engine starts then shuts off, says red triangle with codes p3190 poor engine performance, p3191 engine fail to start, and P0A0F hybrid ecu engine fail start.

    UNLESS: if you clear codes/disocnnect battery, and unplug mass airflow, car almost runs fine, with the check engine only on for mass air flow and intake air temp code(maf unplugged), and no red triangle, full ready, shifts, drives, shuts off, charges battery etc.

    history: cat was stolen, replaced. new denso secondary sensor,
    car was reverse jump started, one fuse on multi main fuse blown, replaced, a 10 and 15 amp fuse also replace/blown, inside air for hvac doesnt work(relay??/fuse??
    check all other fuses for continuity and they are good.

    hv battery one cell replace after it said bad battery, then it said low hv battery, fixed block harness, code went away.

    replace already for testing: throttle body(used), denso mass airflow(new), 12v aux battery from 2012 prius with now issues, both 12v aux batteries test 350 cold cranking amps with midtronics tester,

    checking power and ground to engine ecu and hybrid ecu now,

    again runs almost normal no shutting off if mass airflow unplugged, if connected red triangle, engine fail start, engine poor performance... any help greatly appreciated.
     
  2. PriusCamper

    PriusCamper Senior Member

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    When people start up a Prius with stolen cat the bare wires from 02 sensor can short out the ECU. That doesn't sound like your problem, but it's worth considering.
     
  3. mech1222

    mech1222 Junior Member

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    yes, that was one of my next guesses, replace engine ecu, does it have to be programmed for key or anything or plug and play if you know?
     
  4. PriusCamper

    PriusCamper Senior Member

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    Plug and play as long as you have the right one. Though if you Google "Priuschat ECU reprogramming" you'll get really confused about the truth of what I just said.
     
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    I might test the wiring at the MAF sensor to see if it has everything it needs to work correctly. I like to use small T-pins to backprobe (carefully slide the pin into the wire side of connector - not the open end that goes to the sensor) the connector for testing. Does it have 12V and ground (0V) at the proper terminals, and are the other circuits intact back to the ECM?

    Did you check all fuses? The ECM needs the IGN (7.5A) - underdash - and the EFI (15A) and ETCS (10A) - underhood.

    Does the MAF sensor read anything (different from when the engine is stopped) when the engine spins at 1000rpm but fails to start?

    Other than a blown fuse, I would expect a short in the downstream O2 sensor wiring to affect the driver for the sensor heater- not necessarily anything to do with the MAF.

    If you do want to try another ECM, you can get a used one from ebay, just order the same part number as what you have. It's plug and play- no vehicle specific programming required.

    When I want to try an ECM for testing, I leave the old unit in place and carefully flip the connectors around to plug in the replacement and just let it dangle. If that fixes things THEN I got through the effort to fully swap units. If it don't then I can just plug the old one back in (less work if you don't dismount and remount the ECM).

    Posted via the PriusChat mobile app.
     
  6. mech1222

    mech1222 Junior Member

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    tested +12v and ground...ground is wierd comes from the evap solenoid at rear of car...rad and green to ecu ohm test fine and black 12v+ good. it reads different at idle through techstream then when gas applied. dont know correct readout range? all fuses checked, oddly enough the 10 and 15 amp efi and etcs were blown from reverse polarity jumpstart...

    secondary o2 sensor was not cut, full 02 sensor was tucked away under car...was unscrrewed when cat removed not cut. that 02 was removed/unplugged and replaced with new correct denso.

    pulling ecu to check part number to order ebay one tonight...

    oddly enough tonite is running rough but better and no light on yet with maf plugged in...but still not running smooth enough to pass smog... what the expected rpm/redline when in park and pedal on floor? thanks for the responses,
     
  7. mech1222

    mech1222 Junior Member

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    and there is not any throttle body relearn or throttle position relearn tests for prius'? after changing throttle body or mass airflow?
     
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    As long as the throttle body is clean then removing 12V battery power from the ECM will reset idle adaptations to "like new" and it should run ok (at least not have problems with throttle airflow).

    MAF readings:
    0.01g/s engine off,
    3.8-4.0g/s @1300 cold idle,
    5.8-6.0g/s @2500 cold (ECM will "cut" engine ops if Wide Open Throttle @2600 when cold),
    2.0g/s @1000 hot,
    5.0-5.7g/s @2500 WOT hot,
    21g/s @2500 during initial "force charging" HV battery- MAF and RPM drop as batt level increases
    56g/s @5000 hot WOT @75mph

    If you can keep it running with MAF until the loop status is "closed" - are there any misfire counts? What are fuel trim numbers? (Short term + long term = total fuel trim)

    IDK if there is a fault with the ECM or MAF and that's why it runs poorly, or if there's a different fault and not running with the MAF is putting the ECM into a backup strategy that's covering up the driveability symptoms.

    Posted via the PriusChat mobile app.
     
  9. mech1222

    mech1222 Junior Member

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    different used computer installed did not fix issue.

    tested maf connections to computer with ohm meter good 0.0 ohm. bypass harness wiring to double check.

    it is running fine for few seconds after disconnecting/reconnecting 12v aux battery, no lights or codes, everything connected when it throws red triangle, saying engine fail start, p0a0f-205 and p3191.

    if you unplug maf, it only throws a check engine light for maf, runs ok, runs as long as you want it to, charges battery and shuts itself off.

    plug in maf and it runs for a few seconds then shuts off or doesnt start at all after that or start then shuts off if car is power cycled.

    main realy/fuel pump relay tested ok, pump tested ok...runs fine when no af plugged in...

    all fuses tested again to be sure and all good

    next guess is hybrid control ecu? or upstream o2 sensor but it read in normal specs as does maf when plugged in. hybrid battery relay(s)?
     
  10. ChapmanF

    ChapmanF Senior Member

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    As the MAF sensor is an input to the ECM and the ECM has responsibility for running the engine, and your symptom is clearly that it runs ok in open loop when it thinks it hasn't got a MAF sensor, but not when it thinks it has one, I would not at this point be shifting my guesses anywhere away from that system.

    Swapping the ECM didn't fix the issue, so that tells you the issue isn't the ECM itself just being insane. That's pretty rare anyway; they're solid state silicon (rocks) and fail about as often as rocks do. But the issue is still something the ECM is doing based on the signal it receives from the MAF sensor.

    If it runs long enough to compare Techstream MAF sensor and fuel trim values as mr_guy_mann suggested in #8, that could be a next place to go. But if the signs of life are so brief that a scan tool querying live data can't capture the picture, then something more creative might be needed, like a chart recorder electrically on the MAF sensor output.
     
  11. mech1222

    mech1222 Junior Member

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    i will try to get screenshots today, as well as supply the maf with seperate power and ground... 3 different maf same thing...i will also remove intake manifold and clean, as well as spray on of the old maf with maf cleaner etc, drop .5-1 qt of oil out although its just a the top hole on dipstick, got a donor dipdtick from another 08, same level... and mayb order a second new maf... and will try to get some recordings of maf before and after cleanings

    i appreciate the input very much sir(s).


    also, it has not been actually driven at all for months, should i use a test permit and drive it actual on road for a day to see if the problem changes or running clears out intake if oil inside, i have blocked off the valve cover breather that would suck oil in if pcv was bad but it holds vacuum so should be good, and it actuall made it run better closer to idle...
     
    #11 mech1222, May 12, 2022
    Last edited: May 12, 2022
  12. ChapmanF

    ChapmanF Senior Member

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    here I would whisper mildly that trying too many things all at once can make diagnosis really difficult
     
  13. mech1222

    mech1222 Junior Member

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    not necessarily, and in a sequence lol. ill be fixing things to eliminate them as possibilities also...pcv hoses etc.. there was oil in the intake cavity under the throttle body when i removed it...probably a teaspoon of oil.
     
  14. dolj

    dolj Senior Member

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    With all these new MAFS, is there any chance any of them were OEM? If not you might want to try an OEM sensor or at least a Denso equivalent sensor.
    That is completely normal. A leaking PCV valve not so much.
     
  15. mech1222

    mech1222 Junior Member

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    all are oem, original from car, second used denso, new denso...
    would a leaking pcv valve cause this issue?

    and thats why i thought soemthing else, 3 oem maf same issue would tell me look somewhere else sometimes...

    and since this and most cars are essentially live tuned, air fuel ratio is determined real time/live from reading of upstrem 02 sensor, i may try that as well...first is check intake manifold etc for leaks
     
  16. mech1222

    mech1222 Junior Member

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    second hybrid ecu checked, same issues appears, 12 aux battery swapped with known good to be sure, problem reappears. best to test fuel pressure at pump under back seat with a hacked connector from junkyard to gauge or? fuel psi spec?
     
  17. TMR-JWAP

    TMR-JWAP Senior Member

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    44 to 50 psi
    and maybe the attachment will help a bit
     

    Attached Files:

  18. ChapmanF

    ChapmanF Senior Member

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    Just so we can follow along ... sometimes "OEM" gets casually used here to mean different things, and sometimes there's a strict usage intended where "OE" would be the part from Toyota with the correct xxxxx-yyyyy Toyota part number for the car, and "OEM" would be the exact same part but branded by its manufacturer instead of Toyota.

    So a Denso-branded MAF sensor could be OEM, if it is known to be the exact same Denso part that they supply for Toyota to sell OE. It would also be possible to Denso to sell a MAF sensor that isn't the exact same part they sell to Toyota, but still cross-list it as usable for the application.

    Also, some ways of buying Denso parts are likely to deliver actual Denso parts, and some are likely to deliver, umm, "Denso" parts.

    So, more detail about the parts installed, and where obtained, can help give a clearer picture.
     
  19. mech1222

    mech1222 Junior Member

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    first maf original from car, 2nd maf used from 08 or other second gen, same part number, this new maf denso correct part number cross referenced with rockauto, denso branded box and sensor from amazon.com, direct amazon not third party.

    i appreciate your input sir #2. I forgot, prius guy are 2x more technical than any other mechanics lol(goes with the ice plus 2 electric motors and battery, 4x more propulsion components than a normal car), yes you are correct in the oe vs oem definitions. these are 2x oe sensors, and 1x oem. the new oem denso sensor is different part number etc, than the first used oe 2x sensors, i will check differneces and maf output of each sensor at certain rpms, after i double check intake for leaks, after first checking fuel pressure. at this point i am inclined to think it is a simpler problem: vacuum leak or fuel pressure or something else simple, going to check ohm load/continuity from battery positive and negatuive to computer power supplies to ensure sensor reference voltage is not issue...

    and yes very easy to get something that says denso on it, and its fake, box and all...i hope shipped and sold direct from amazon is actually denso though...

    i thouroughly suggest denso part numbers are checked at amazon for price comparison as i have saved alot on denso ac compressors and other things buying from amazon direct.. $50-100 over rockauto even, and you can open a page and refresh it a few times a day or week and the price will fluctutate and you can get a really good price sometimes that way. or put it in your cart and check price fluctuation that way.

    appreciate the fuel pressure info also sir #1


    at the end when its fixed i will post as much as i can including fix and process to get there
     
    #18 mech1222, May 16, 2022
    Last edited: May 16, 2022
  20. ChapmanF

    ChapmanF Senior Member

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    We can hope. In this Automotive Anti-Counterfeiting Council white paper, they describe this shipping practice that "at least one" online marketplace uses (page 13).

    The white paper doesn't name what online marketplace they mean by "at least one", but I have definitely had that happen to me when buying from Amazon. You can clearly tell their computer system tries to match up product numbers/descriptions on offer from different sellers (so it can give you "four other sellers have this product for less but the shipping might not be free" or whatever), and it's not uncommon to read through the reviews on one listing and realize they are combining reviews people have given that "product" from different sellers (sometimes the review even mentions an email or phone conversation with the seller, and it won't be the seller you're looking at).

    I definitely bought a product last year (not an auto part, a knife sharpener) that flat-out arrived on my porch with the packaging and logo of the seller I had deliberately decided not to buy it from. One of the stones was cracked, and I requested a replacement, and that came from somewhere yet again different.

    It clearly seems that they are letting their computers "identify" matching products (seller A product X and seller B product Y look from their descriptions like they must be the "same" thing), and then say "look, Chap ordered X from A but we've got a warehouse closer to him with a whole pile of Y from B, we'll just send that."

    But I was buying from Amazon marketplace sellers, so there's still a chance they don't substitute like that on a "sold by Amazon" purchase.
     
  21. mech1222

    mech1222 Junior Member

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    possibly the issue is the cracked intake manifold:)

    01-09 intake mainfold are the same according to interchange
     
    #20 mech1222, May 17, 2022
    Last edited: May 17, 2022
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