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Starts and idles but bogs when with throttle

Discussion in '1st Gen. Tacomas (1995-2004)' started by RustBunny, Oct 31, 2024.

  1. Nov 1, 2024 at 6:43 PM
    #21
    fireturk41

    fireturk41 I like to break shit!

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    If you can try unbolting your cat and see if it works. Go back through your plug job and check for any crossed or pinched wires, corroded, or loose connections. If you can get a hold of one id also try replacing the iac, though usually the issue is the opposite
     
  2. Nov 1, 2024 at 7:10 PM
    #22
    RustBunny

    RustBunny [OP] Active Member

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    Yeah me too :/
    But yeah I’ve checked the fuses a few times actually
     
  3. Nov 1, 2024 at 7:15 PM
    #23
    RustBunny

    RustBunny [OP] Active Member

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    Nope, that’s not it either. I unbolted it upstream of the cat today and no change, other than breaking off one of the studs due to many miles and many years of salty living, so I’m now down to just two studs holding that thing on

    Same thing happens if I slowly open the throttle, just happens a little slower that’s all.
     
    Frog4aday likes this.
  4. Nov 1, 2024 at 7:28 PM
    #24
    RustBunny

    RustBunny [OP] Active Member

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    Yeah I unbolted upstream of the cat today and no change, and I’ve been through all the wires and everything so many times, each time thinking I’ll see something I’ve missed before, but still nothing. Maybe somebody can send me the plug wire diagram again, is it possible some online are wrong? even though I’ve checked and double checked that, and it seems like it’d be impossible to mess them up since they’re different lengths too, it’s just acting like the plugs wires are just off or something. I first just assumed that was the case and thought this was nothing, “oh, I must have just crossed two of the wires to the plugs, no biggie” but weeks later now, I’m still here, and completely stumped

    I wondered about the IAC, just cause it’s back in that area where I was disconnecting stuff to remove the intake, but I dont really know anything about those or potential problems with them. Even used on ebay I’d be lookin at about $145. So how likely do you think that is? and is there some way to test it? kinda seems like something that would throw a code if it was malfunctioning, but that’s just a guess
     
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  5. Nov 1, 2024 at 7:32 PM
    #25
    RustBunny

    RustBunny [OP] Active Member

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    Yeah I don’t understand this enough to know what the backfire was all about. That has only happened a couple times, when I’m kinda pushing it, trying to force it to rev up a little bit. Was kinda hoping that would be a clue for someone else that knows more than me.

    The fan was definitely pretty loud blowing a lot of air on the recording, it seems to be idling ok at a least.
     
  6. Nov 1, 2024 at 7:34 PM
    #26
    fxntime

    fxntime Well-Known Member

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    If you have tried everything else then your injectors aren't getting a signal to increase the fuel when you open the intake butterfly. Are you sure you didn't accidentally knock off a connector somewhere or miss one?
     
  7. Nov 1, 2024 at 7:41 PM
    #27
    bigmw

    bigmw Not-So-Well-Known Member

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    Bunch of different mods
    I think you mentioned a new fuel filter?
    How about cleaning the injectors? Is the fuel pump running correctly?

    Edit: I'm thinking that if it's not the fuel issue, then I would also swap out all related fuses and relays, one at a time, for a new one
     
  8. Nov 1, 2024 at 7:56 PM
    #28
    ControlCar

    ControlCar My Moto: Help & Learn…period.

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    Hmmmmm
    your original code

    IMG_4860.png
     
  9. Nov 1, 2024 at 8:07 PM
    #29
    ControlCar

    ControlCar My Moto: Help & Learn…period.

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    The backfire confirms fuel issue
    More so fuel delivery signal from a sensor

    appears you can cross out causes #1 and #4 bc u addressed
    (IMO not FP bc engine runs)

    #3 cause O2
    This would be 1st rpr choice
    Front O2 mainly controls idle fuel/air mixtures
    You can test O2 sensors with Ohm readings
    Tons of short vids out there

    #2 MAF
    1st would be to clean MAF
    Don’t skimp and buy that expensive stuff
    Brake cleaner will dmg MAF
    That cone filter scares me
    Lets in tons more air….but Unk if MAF can keep up with air/fuel ratio

    start with front O2 (test/replace)and clean MAF
    Let everyone know what results are!
     
  10. Nov 1, 2024 at 8:11 PM
    #30
    Pibbles99

    Pibbles99 One more cast

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    :popcorn:
     
  11. Nov 1, 2024 at 10:42 PM
    #31
    RustBunny

    RustBunny [OP] Active Member

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    Yes I’m sure on that. I’ve been trying to get this going for at least a couple weeks before posting on here, so i’ve taken it all apart and put back together many times. I’ve also confirmed i’m getting power to all the coils…
     
  12. Nov 1, 2024 at 10:44 PM
    #32
    RustBunny

    RustBunny [OP] Active Member

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    I put in a new fuel pump, fuel filter, and did the injectors, maybe a year and a half ago, so I feel pretty good on all those. All fuses are good, but do you know which relays would be effecting fuel delivery?
     
  13. Nov 1, 2024 at 10:56 PM
    #33
    RustBunny

    RustBunny [OP] Active Member

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    I regularly clean the maf sensor with, yes, proper maf sensor cleaner.
    I’ve been running those same air filters since 2015 when I put this motor in, and it’s driven with those to the bottom of argentina, and back, without problems, so while I’m no expert, and maybe they’re not the best? I don’t know, but I feel pretty confident that it’s not part of this problem. (usually it has a filter-wears brand cover over it, but it’s off since I keep taking it all apart).

    There’s no way I can remove the o2 sensors without cutting them out at this point due to rust, but that wouldn’t cause it to be this bad (undrivable) would it? and that would definitely be throwing codes I’d think.

    I reved it best I could today for a while to get it nice and hot and still no codes
     
  14. Nov 1, 2024 at 11:28 PM
    #34
    RustBunny

    RustBunny [OP] Active Member

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    While I’m still totally stuck, I wanted to express my utmost gratitude to all of you. So many of you have been responding, being si helpful all with really good ideas, and important things to check, and you’ve all been so nice and respectful all while selflessly helping me. Thank you all so so much, I really really appreciate it
     
  15. Nov 2, 2024 at 6:45 AM
    #35
    bigmw

    bigmw Not-So-Well-Known Member

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    If you haven't checked relays, that would be my first go to. I don't know 1st gen, but there have to be diagrams on tw somewhere. And by checking relays, I mean replacing them with a new good one, one at a time. I imagine it would only be the one - fuel pump relay, but maybe there are others
     
  16. Nov 2, 2024 at 7:27 AM
    #36
    RustBunny

    RustBunny [OP] Active Member

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    It’s my understanding that if the relay is bad the fuel pump won’t run at all, am I wrong in that?
    I have a hidden fuel pump shut off switch I wired in, and if that’s off, it won’t even start, zero fuel.
     
  17. Nov 2, 2024 at 11:42 AM
    #37
    ControlCar

    ControlCar My Moto: Help & Learn…period.

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    Can u post a pix of the rusted front O2 sensor/bung/surrounding exhaust pipe?

    hypothesizing here
    But if E pipe is “weldable”
    $75 to weld new o2 bung(muffler shop(I don’t have welder))
    Leave the old one…..install new one/new bung
     
  18. Nov 2, 2024 at 12:58 PM
    #38
    RustBunny

    RustBunny [OP] Active Member

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    I do have a welder, but a couple problems with that are: my welder is in oregon, and I just crossed the border so I’m in new mexico, but rural new mexico, and of course the truck doesn’t drive, so it’s not super easy getting it to a place that I could do that at.

    So… how likely is it that that is the entire problem? I could get it towed one way probably, but if that didn’t fix it then I’d be in a worse situation than I’m in right now.

    Could that really cause this without throwing any codes? and happen all at once, making it completely undrivable?
     
  19. Nov 2, 2024 at 2:42 PM
    #39
    ControlCar

    ControlCar My Moto: Help & Learn…period.

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    Ok I see logistics are an issue

    what about this…..to rule out too much fresh air metering for MAF to handle

    take off cone filter
    And then tape up round inlet and only leave a slit top to bottom Greatly restricting amt of air
    As a cheap test to see if changes throttle response
     
  20. Nov 4, 2024 at 12:26 PM
    #40
    RustBunny

    RustBunny [OP] Active Member

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    Couple sensor question, considering these symptoms, and still not throwing any codes…

    This couldn’t be an issue with the IAC, since it idles fine, is this correct?

    What about the throttle position sensor? any easy-ish way to test that?

    Someone mentioned it could be the cam position sensor, does that make sense with these symptoms? and again, still no codes ¯\_(ツ)_/¯
     

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