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  1. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well, did some more testing. I scoped the TPS and it has a weird blip every now and then where the voltage drops to 0.16v, the rises to 0.7v. It only lasts 42 microseconds, so I don't know if that matters or not. I put some resistors in instead of the TPS but that didn't change anything. Then I...
  2. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yeah, I thought about that a lot of times. Unfortunately I need to sell the boat, so for a boat getting listed for a bunch of money, things have to be proper, I don't think a buyer would understand a carburetor on there :( Last time the engine ran well was when I turned the distributor and...
  3. vroom ZOOM

    454 mag mpi chuggles/stalls

    Sorry should have been more clear, the new FPR solved the issue of the fuel pressure slowly dropping after the engine turned off, it just didn't solve the initial issue.
  4. vroom ZOOM

    454 mag mpi chuggles/stalls

    okaaay... And I am back to messing with these engines. Seriously, if I had the $$$ I would go with 8.1s at this point. Always my bad luck with a MEFI motor. Anyways, I put together the starboard engine over the winter, it should be good to go. I then went back to messing with the troublesome...
  5. vroom ZOOM

    454 mag mpi chuggles/stalls

    WELL.... My problems didn't stop from the last post... Far from being trouble free. After doing the dizzy turny wire swappy thing that made the engine run like BUTTER, it ran good the next day too. The day after that, it ran good again, so I decided to finally take the boat out for a test run...
  6. vroom ZOOM

    454 mag mpi chuggles/stalls

    Weird update #102380703023! Today, I swapped the intake manifold between both engines as that is the ONLY part I have not tried. Put it on and the engine started then quit. Unplugged the coolant sensor and it did much the same as before. *Flashback from a couple of months ago* I remembered...
  7. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yes, the intake came from the old engine, and that is the only part I have not tried moving from the other engine, aside from the transmission. I will move it over today. As for parts 2 and 3 there isnt even a hole for them in the intake. No fuel in the vacuum line to the regulator. Flame...
  8. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yes I can... havent tried unplugging the iac but will try that today.
  9. vroom ZOOM

    454 mag mpi chuggles/stalls

    I will put my light on it tomorrow.
  10. vroom ZOOM

    454 mag mpi chuggles/stalls

    well, :mad::mad::mad::mad::mad:🤬🤬🤬🤬🤬🤬🤬🤬😤😤😤😤😭😭😭😭😭😭😡😡🤬🤬🤬🤬🤬🤬🤬🥵🥵🥵🥵🥵😨😨😨🤬🤬🤬🤬🤬 I was REALLY hoping the scope would find and least SOMETHING... What it found was that the injector signals on both engines are exactly the same, good clean pulses. Also used it to probe all the grounds and powers to the...
  11. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well, I picked up a scope and spent some time playing around with it. Hooked it up to my car and got some waveforms. Will go to the boat next week and do some testing.
  12. vroom ZOOM

    454 mag mpi chuggles/stalls

    I just did a brake cleaner test, I unplugged the PCV hose and when the engine went to stall I shot some brake cleaner in there and it immediately picked up. I had to spray A LOT in there before it picked up. Not just a little shot, but a good steady stream! I am now certain that this engine is...
  13. vroom ZOOM

    454 mag mpi chuggles/stalls

    tried putting the cheap injectors in. still wont run. will try the iac right now.
  14. vroom ZOOM

    454 mag mpi chuggles/stalls

    Just got the troll mode thing figured out. unfortunately that did not point me to my issue. The neutral switch just had some resistance to ground. unplugged it but nothing changed. on to the next thing.
  15. vroom ZOOM

    454 mag mpi chuggles/stalls

    If I can get it to stay running the IAC will go over 100. Check the data files I emailed you with the good and bad engine.
  16. vroom ZOOM

    454 mag mpi chuggles/stalls

    On my running engine the pulsewidth is 3.5, and map is around 21. BUT the port engine did decide to idle today at one point, albeit very rough and borderline stalling. I did record the data though. Injector pulsewidth and MAP was at 3.5 and 21, just like on the starboard engine but it was...
  17. vroom ZOOM

    454 mag mpi chuggles/stalls

    Transmission Mufflers and exhaust plumbing shift cables throttle cable water pump load anticipation switch trans temp switch trans harness knock sensor heat exchanger longblock(inc. heads and valve cover) analog temperature sender analog oil pressure switch engine mounts
  18. vroom ZOOM

    454 mag mpi chuggles/stalls

    Okay... so I found something else funky yes but it will rev to almost 3k then almost stall, then catch and rev up again etc. Any ideas about how the ecms know which engine they are on and that turns troll mode on or off even though it doesnt exist? Also today I had to move the boat into...
  19. vroom ZOOM

    454 mag mpi chuggles/stalls

    Ok, as I dig through this things get super wierd. in diacom, there is a parameter called "Troll Mode input". I disregarded it at first thinking that it was not changeable and programmed into the ECM. When I put any ECM on the running starboard engine, troll mode is "OFF" all the time. When I...
  20. vroom ZOOM

    454 mag mpi chuggles/stalls

    I think it is time for me to invest in an oscilloscope. I want to compare the injector voltage and current waveforms on both engines to see if the injectors are actually opening as commanded by the ECM. Also hook it up to the ecm power and ground feeds and distributor rpm signal to see what is...
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