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Thread: No Injector Pulse After 5.3 Swap - VATS?

  1. #1
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    No Injector Pulse After 5.3 Swap - VATS?

    Hello I have done research on this but it seems to be one of those issues everyone online argues which is correct. I've had great help here so I thought i would take a shot. To disable VATS, do I just change to no in system, disable the two related codes, and just do "write calibration"? Got my project truck to a point to start it up today, but I believe I am not getting any fuel on a crank no start and just trying to rule out possible causes. Reason I still question this one is because I am still getting a flashing SECURITY light on my dash. I "read" the file and it still is set to no, but wondering if I do in fact need to "write entire".

    2002 sierra 1500 truck and stock ecu, and swapped in a built 5.3 from an 05.

    I have spark, air, and no fuel. I have not tried a noid light, but here is where I am at:

    3bar SD startup tune (confidant in the tune, but can provide)
    Tried cranking with and without the factory MAF, due to built in IAT
    60psi fuel pressure at the rail (I have 80lb injectors and have not installed my larger fuel pump; assume it can at least idle the bigger cam)
    12.6V at the injector wires itself
    Will run only when spraying starting fluid
    No pulse width reading on VCM scanner on crank or "running" on ether
    Cranks healthy but definitely no firing
    No codes

    So I believe my issue is not getting a signal to fire the injectors. Only things I can think of is the VATS, or the oil pressure switch. I have read the possibility of a bad switch can not allow fuel to turn on I am not sure with these trucks. I currently have my mechanical gauge in the port but have not tried installing the sensor yet. Or my VATS is acting up and I did not disable correctly. Any thoughts? Any channels I can add on the scanner that may help me figure why fuel is cut?

    Also, crank sensor is new and good (Installed new when the 5.3L was still in the 05), Cam sensor is new but have not tested.

    Thank you
    Last edited by Dcall98; 09-09-2024 at 10:26 PM.

  2. #2
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    Is the MAF failed in the calibration? When you upgrade the OS to the 3 bar you get a VE table full of garbage values. Did you populate the VE with legit values. That is where posting the file will help people figure out what is wrong.

  3. #3
    Tuning Addict 5FDP's Avatar
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    There is no "can provide" the tune file, this is an always provide the tune file forum.

    You want help, the tune must be posted. We have no idea what you changed in the tune, so without it we can't see if you overlook something.

    And to answer the VATS, that on;y required a write calibration on that computer. The 3 bar OS changed required a write entire though.
    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.

  4. #4
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    Ah sorry I am new to the forums thing I will post it on here. I believe I have done all correctly. Not a full tune but enough to get it idling I hope.

    Some info:

    223/230 TSP stage 4 turbo cam w/ valvetrain to match
    port and polished heads
    80lbs injectors
    No tuning for boost yet, just wanted to fire it up

    Base Startup.hpt

  5. #5
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    Bingo Look at your VE table.

  6. #6
    Tuning Addict blindsquirrel's Avatar
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    And, the change to 2-bar OS MUST be done with Write Entire the first time.
    GM Gen4 Injectors v2.1.xls
    "My life has become a single, ongoing revelation that I haven't been cynical enough."


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    I will go ahead and say I have lost confidence lol. Are you talking about the new "Main VE" table I assume? I am new to speed density tunes so I figure I would come here to ask those smarter than me.


    And yes, Write Entire was done for the first time for the new OS

  8. #8
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    Look at the main VE table in your stock tune then look at the Main VE table in your 3 bar tune.

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    Look rather similar lol. Well I will always admit when I am dumb. Any chance you could point me in the right direction for this fix? Learning SD tuning myself

  10. #10
    Tuning Addict blindsquirrel's Avatar
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    GM Gen4 Injectors v2.1.xls
    "My life has become a single, ongoing revelation that I haven't been cynical enough."


  11. #11
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    Alright I see. Was a missed step when looking up. I will make some corrections to the Main VE and try it again tomorrow

  12. #12
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    Problem solved. Finally threw a code for a crank sensor. Test voltage, replaced, and it fired right up. Did not expect that being a new sensor that I used a couple times. Oh well I highly appreciate everyone's help!

  13. #13
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    You had to have changed that 3 bar VE table too or I'm calling BS.

  14. #14
    Senior Tuner edcmat-l1's Avatar
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    Same here it ain't running off that VE.

    Quote Originally Posted by Dcall98 View Post
    I have spark, air, and no fuel. I have not tried a noid light, but here is where I am at:
    If it were a bad crank sensor you would not have any spark.
    Last edited by edcmat-l1; 09-10-2024 at 04:40 PM.

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    Yes I had to dip earlier but wanted to throw something up here quick. I did in fact correct the Main VE table on the tune. And actually it was attempt to start it with the corrected table is when I got the crank sensor code. You are definitely right though it probably would have barely run if at all without it and I am glad I posted that up and you guys had saw that. I figured it was more of a physical problem but glad you guys hassled me lol.

    I too thought it had killed spark with a failed sensor. But at the same time it "ran" like normal on a few seconds of spray, and had zero pulse on my injectors. But swapped that sensor out and it fired right up without a hiccup

  16. #16
    Tuning Addict blindsquirrel's Avatar
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    That's just not possible. They will not run at all with no crank signal. No RPM reading on the scan tool, no spark, no injector pulse, no fuel pump activation after the initial key-on prime. It will not use the cam sensor as a backup like a limp-home mode. It WILL run normally without a cam signal, with possibly a long crank symptom, but otherwise normal.

    Per GM service manuals: "If the CKP pulses are lost the engine will not run."
    GM Gen4 Injectors v2.1.xls
    "My life has become a single, ongoing revelation that I haven't been cynical enough."


  17. #17
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    Well that is interesting. I honestly did not test spark, I assumed it was good when it would fire with some starting fluid. Even turned on the fuel pump via the vcm scanner to rule probable causes at the time. But my friend as my witness she ran the few seconds of a light spray he shot into the throttle body. But regardless, it idles great with the new sensor in place.

  18. #18
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    It's possible if the sensor sent a pulse train briefly. Flaky sensor, but not entirely dead.

    New crank sensor means you should do a crank relearn.

  19. #19
    Senior Tuner edcmat-l1's Avatar
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    Quote Originally Posted by Dcall98 View Post
    Yes I had to dip earlier but wanted to throw something up here quick. I did in fact correct the Main VE table on the tune. And actually it was attempt to start it with the corrected table is when I got the crank sensor code. You are definitely right though it probably would have barely run if at all without it and I am glad I posted that up and you guys had saw that. I figured it was more of a physical problem but glad you guys hassled me lol.

    I too thought it had killed spark with a failed sensor. But at the same time it "ran" like normal on a few seconds of spray, and had zero pulse on my injectors. But swapped that sensor out and it fired right up without a hiccup
    Of course you did, that's why it ran. You can believe it was the crank sensor, we know better.

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  20. #20
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    I've always heard that using starter fluid to check for spark wasn't a good test anyway and it can light off on compression only.