Results 1 to 13 of 13

Thread: Head scratcher - crank no start now. Inj pulse and dynamic air flow without running

  1. #1
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9

    Head scratcher - crank no start now. Inj pulse and dynamic air flow without running

    OK, complete noob at this so probably an easy answer, just hard for me to see.

    Trying to get first idle set so I can get into refining it, then getting it moving to start the real tuning. Got it to idle poorly, but good enough, would start and idle up to full operating temp consistently. Was starting to get it worked through in gear. Started dying out after a little bit, then more often. Seemed like it was starving of fuel, didn't surprise me as I have no idea how much is in the tank. Added 5 gallons and still had worsening problems. Had good fuel pressure at the rail. Started thinking it may have had condensation build up as it sat over last winter and maybe a slug of water came through. I took my fuel pressure gauge hose and pumped some fuel into a jar, looks good, no water. Now it won't start at all.

    When I log it before trying to start it will show ~5.4 ms injector pulse width average, which may jump up to ~12 or more when I crank it (it was ~3.6 or so when I did have it idling). It shows ~2,000hz MAF, 50lbs of Dynamic Air Flow, and a few other things, all with the engine not running or even being cranked.

    I'm leaning towards a grounding problem but I've checked them. I haven't checked them at the ECU side of the harness yet but that's my next move.

    (Of course I decided to get into this by doing things the hard way: LY6 with 24x reluctor and 1x cam gear. P01 ECU, Holly Sniper DBC throttle body)

    Here's a log of trying to start it this afternoon
    24-10-05 14-42-56.hpl

    Thx for any help,
    JR

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
    Posts
    13,801
    Post the tune file.

    What injectors?
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    The tune is a hot mess, just starting on it. I had turned off MAF, fuel trims, etc to just mess with the VE as I was getting idle going. The injectors are old LY6 injectors (12580681) that were decapped (I know, I know). I did have them flowed and they were all at the 62lbs in the tune file. I have corvette regulator to match the return-less Gen IV fuel rail.

    Also, here is the log that was running when it was idling then started this problem.

    24-09-30 16-49-15.hplP01 updated MS Startup c w-EGR.hpt

    Really confused as to why I'm getting injector pulse width, MAF, Dynamic air, etc before I even hit the starter.

    JR

  4. #4
    Advanced Tuner
    Join Date
    Mar 2009
    Location
    Andover, MN
    Posts
    707
    there is quite a bit off there. Give it some more startup airflow and soften your overspeed start. For humanities sake, replace the fuel injectors.

  5. #5
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    Yeah, pretty much at stage zero still. It was starting and idling ok, not great, but ok. Now, nothing with or without throttle. Considering how it just changed, really thinking a ground issue but they all look good.

  6. #6
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    Welp, update. Checked all the grounds, checked them all through the harness, did a quick check on the harness to see if anything was shorted to ground that wasn't supposed to be, no issues. I do think my Cam Sensor is toast though so getting another one. My understanding is that even with a Cam Sensor out, it would start eventually but no go. We'll see if it helps.

    I also tried a stock 6.0 P59 ECU that I had and it was doing the same thing, no start, occasional sputter and backfire, so pretty it's not the crappy tune.

    A question on Cam Sensors. I have a replacement for the Gen IV coming in, but thinking I should have gotten one for a LS2 out of GTO. I haven't found any technical info but I understand the Gen IV is 5v, while the LS2 out of the GTO is consistent with the 12v out of the Gen III ECU. Any guidance?

    Thx
    Last edited by Hopeless Diamond; 10-06-2024 at 11:14 PM.

  7. #7
    Tuning Addict blindsquirrel's Avatar
    Join Date
    Apr 2017
    Location
    Meridian MS
    Posts
    9,238
    P01/P59/E40 are 12v reference for both CMP & CKP. E38/E67/others are 5v for both.

    '05-'06 GTO, '05-'06 Trailblazer/Envoy/etc. 5.3, '05 Corvette have a front mount, 12v CMP sensor.

    screenshot.07-10-2024 00.42.26.png screenshot.07-10-2024 00.49.01.png screenshot.07-10-2024 00.47.50.png
    GM Gen4 Injectors v2.1.xls
    "My life has become a single, ongoing revelation that I haven't been cynical enough."

  8. #8
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    4,624
    Have you pulled the plugs? I'd bet they're black as coal. I'd start with the basics. Replace the plugs.

    The injectors need to go in the trash.

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]

  9. #9
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    Thx Yep, gotta get a different CMP.

  10. #10
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    Actually the CMP I had ordered was for an E38. I am able to log it now. Unfortunately, still no Joy, just turns over and over. Does sort of want to fire, but not really. Have reloaded various tunes where it was idling as I was starting the process but nothing.

    I am ordering new injectors, but considering I did have idling on the ones in there, not sure thats my immediate problem. Almost seems like it's so far out of time that it won't fire, thought the CMP might help with that.

  11. #11
    Senior Tuner edcmat-l1's Avatar
    Join Date
    Aug 2006
    Location
    5BA8
    Posts
    4,624
    Have you checked the plugs?????

    EFI specialist
    Advanced diagnostics, tuning, emissions
    HPtuners dealer and tech support
    email=[email protected]

  12. #12
    Tuning Addict blindsquirrel's Avatar
    Join Date
    Apr 2017
    Location
    Meridian MS
    Posts
    9,238
    E38 is a 5V sensor. E40 is a 12V sensor. P01/P59 have a 12V reference, not 5V.
    GM Gen4 Injectors v2.1.xls
    "My life has become a single, ongoing revelation that I haven't been cynical enough."

  13. #13
    Potential Tuner
    Join Date
    May 2023
    Location
    Chumstick, WA
    Posts
    9
    Interestingly, I've gone to a few different GM parts sites and looked at the CMP for the LY6 (07 Yukon XL 2500 donor vehicle) and a 05 GTO and they come back with the same sensor. The one I got from NAPA this am is a beige one. Seems to work so far, may have a short life though.