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  1. 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...
  2. vroom ZOOM

    454 mag mpi chuggles/stalls

    tried putting the cheap injectors in. still wont run. will try the iac right now.
  3. 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.
  4. 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.
  5. 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...
  6. 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
  7. 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...
  8. 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...
  9. 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...
  10. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well, I just honed in on another huge clue. I ran a data log through diacom on the working engine to get some numbers. At idle, the IAC is around 17 counts and the injector pulse width is 3.4 ms. On the broken port engine, the injector pulse width is 2.5 ms, even going down to 1.8! So for some...
  11. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yes it is the TBI style system (delco EST). No crank sensor. I swapped entire distributors. Both work on the starboard engine.
  12. vroom ZOOM

    454 mag mpi chuggles/stalls

    about 15 seconds. That is an interesting observation though, I will go see if it changes in a longer timeframe.
  13. vroom ZOOM

    454 mag mpi chuggles/stalls

    ECT sensor seems to be reading just fine.
  14. vroom ZOOM

    454 mag mpi chuggles/stalls

    That was the first thing I did, 45 psi solid all the time.
  15. vroom ZOOM

    454 mag mpi chuggles/stalls

    Well I am completely pulling my hair out. Will call the place I bought the motor from and see what they have to say. Its fair to say I have tried every single part from the other engine other than the longblock and it still wont run. I also tried removing the mufflers to see if there maybe was...
  16. vroom ZOOM

    454 mag mpi chuggles/stalls

    no, clear bright red.
  17. vroom ZOOM

    454 mag mpi chuggles/stalls

    Did more troubleshooting today. I think at this point I am starting to consider some kind of issue in the transmission. it is a velvet drive 5000v. Is it possible for it to fail such that it somehow tries to engage forward and reverse at the same time and stalls the engine out?
  18. vroom ZOOM

    454 mag mpi chuggles/stalls

    No damper. This is a MAG, not an L29. Serial number is 0L394105, sorry for not posting it earlier.
  19. vroom ZOOM

    454 mag mpi chuggles/stalls

    well, started doing stupid stuff cuz thats all I have. Swapping the fuse cube swapping the starters running the engine directly off booster cables to the battery checked the lifter preload tried wire harness swap again tried distributor swap again tried swapping spark plugs from one engine to...
  20. vroom ZOOM

    454 mag mpi chuggles/stalls

    Yes, I guess the temp went down a little as it started pulling air through the plenum.
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