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Fuel Injectors not firing

Discussion in 'Generation 1 Prius Discussion' started by gothstone, Oct 20, 2019.

  1. gothstone

    gothstone Junior Member

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    So I'm still fighting P3101 and P3191. Thought I had it the other day, but I think the ECU just glitched for a sec or something. I'm done a ton of testing and checks, but hers the important part. The Injectors open with a direct tap from battery, and I ran pressurized carb cleaner through top clean them till they had a nice spray pattern. Replaced the filters and o-rings while I was there. I have 48 psi of fuel pressure to the rail. I can only test this from TechStream by turning it on, not with engine running as I couldn't jurry rig up a pass through connection. Using a endoscope through a spark plug hole I verified that the injectors are NOT spraying fuel. It will run on ether fairly well when I can keep the right amount going in. The injector resistance is within spec. Continuity from #10-#40 from ECU to each injector is fine, and there is no open or short. I really wish I had a scope to see if the ECM was firing them, but I don't.

    So at this point, I'm pretty sure the ECM is not firing the injectors. I think that means its bad. I don't get any other codes (well, ok I have cause several but always along the lines of hey moron, plug the MAF back in) and I would think anything that pissed off the ECU enough to cut injectors or fuel would throw a code.

    So before I spend time and money getting a replacement ECU to test, anyone have any other ideas?
     
    #1 gothstone, Oct 20, 2019
    Last edited: Oct 21, 2019
  2. ronlewis

    ronlewis Active Member

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    How do you get an ECU to test? I've wondered because one of my parts car throws and ECU error. It's not worth buying a new ECU and I don't know how to be sure any used one I bought was working in case it made no difference. probably really need a known good one out of a running car, but seems like there was some sync procedure that I didn't want to mess with.
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    No chance it’s something simple/bigger like a bad ground to the ECU?

    If you can’t see the injector pulse because of no scope, can you hear/feel them snapping when you give them voltage?
     
  4. ChapmanF

    ChapmanF Senior Member

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    You might be experiencing the Gen 1 Startless Start Syndrome, which I don't know that anyone has fully explained yet, but maybe we get a little closer every time it happens to somebody who takes notes.
     
  5. gothstone

    gothstone Junior Member

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    I just ordered one off ebay, and I have to hope its good. I did make sure it was the newest model number, so I shouldn't have issues with flash versions. Ya, I'll probably have to go through the 30 min mating ritual. I might be able to get a absolutely know good one off the same guy I got my battery pack and some other parts from. But I'm swamped this week getting my climbing gym ready for a big competition, so it will have to wait and I don't know if he will struff have it. The ebay one was only $25. If nothing else maybe I'll be asking my buddy Ron if one of the 7 dwarves can spare a ECM. :) I'm surprised you haven't swapped any of yours around for the one with an issue.
     
  6. gothstone

    gothstone Junior Member

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    I've run every possible volt meter test to the ECM, all test just fine. When I was pulsing them in my quiet garage to clean them, sure I can both hear and feel it. When the noise and vibration in the engine bay I did try it, but I couldn't tell anything for sure.
     
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Use a mechanic’s stethoscope to focus on the injector sound.

    Don’t have one? Use a long socket extension. Put it on an edge of the injector and rest the other end on your head under your ear so you’ll pick it up through bone conduction.
     
  8. gothstone

    gothstone Junior Member

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    Looking through your thread and answering things as I see them. I didn't do the volume tests on my injectors, just cleaned till the spray pattern was nice and even. Really only had one that was kinda crappy to start with. I did try a 12v batt disconnect with no luck. I've also cleared codes through techstream repeatedly. I've got the kid working on recharging blocks since my last attempt with plug 1 removed tried to start for a lot longer and pulled the pack WAY down. In my situation I know that a couple meth heads were messing cluelessly with the car. God only knows what the original issue was and what all they messed up trying to fix it. They could easily have zapped the ECU in some manner that partially scrambled it or fried one specific portion of the board. I haven't physically inspected it inside. I can't hear the fuel pump when it running, but I should look over my freeze frames to see if it recorded anything about it being on. I'm currently running of this battery - SP12-75 IT SigmasTek genuine SLA Battery (12V 75AH) . It doesn't fit, but I happened to have it laying around and its a mile over spec for this thing. I generally have it on a charger as I keep leaving the computers on forever while looking at codes and monitoring block charges with dr prius. So I'm pretty sure I have no 12v issue. I can confirm that the spark plugs are firing. It's definitely not too rich, cylinder head is dry as a bone. Really wish I have an oscilloscope to test with, but not an option unless someone can lend me one for find a really cheap one that they might actually trust. What I saw of cheap ones on amazon was really disappointing.
     
  9. gothstone

    gothstone Junior Member

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    Cool, thanks. Will see what I or the kid can do next week after the comp.