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Thread: New fuel system, bad surge.

  1. #1
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    New fuel system, bad surge.

    Recap: LS1, 212/218 114LSA cam, 11:1 compression, headers, truck intake and stock throttle body.

    Went from return style system to returnless.

    New fuel cell, 255lph fuel pump, new 6an lines, Vette filter, return less rails and 36# flex fuel inj. Started it up and fired right up. Idled fine.

    Went for a drive to put more gas in it and everytime I came to a stop it surged and died. Fan came on and it would surge worse. Got gas ,Put it in gear and surge was so bad it would die. Luckily I had the lap top with me and was able too add fuel and somewhat slow the surge.

    Got home and put my VE table back stock and added a little timing at idle. Surge almost went away for in gear and still had a tiny surge idle in park but had alot of surge when fan comes on. Smells rich

    I started logging idle. It was pulling a lot of fuel at idle. I tried pulling fuel with RTT and it would make the surge come back. So I dropped my idle timing and found a happy medium with fuel and timing at idle and in gear for no surge. It's still pulling -1.8 on the stit and the surge comes back violently everytime the fan kicks on. Also still smells a bit rich.

    Every time it is surging and the voltage oscillates I can hear the fuel pump surging along with it.

    I'm wondering if it's this cheap fuel pump I was recommended?

  2. #2
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    Tune and log...

  3. #3
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    Return vs returnless isn't a really good way to name these things.

    Are you using a vaccum referenced regulator before and not now or vise versa? If so did you change your injector data to match?
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  4. #4
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    I fixed the surge. Issue was my Corvette filter/regulator failed and had my fuel pressure way too high. So I bought an EFI adjustable fuel pressure regulator. It's mounted on the return port of the fuel cell.

    Now it's falling on its face as soon as you go to accelerate when in gear. Like it's running out of gas.

    Fuel pressure drops 1psi from 58 to 57 when it does this so fuel pressure is good. I have 1 gauge on the fuel pressure regulator and another on the fuel rails.

    These 06 tahoe return less fuel rails now with Only 1 fuel line to the rail, no return line. Old rails had a vacuum referenced regulator. I did copy the injector data from the 06 tahoe tune.

  5. #5
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    Current tune.
    Attached Files Attached Files
    Last edited by 12ramhemi; 1 Week Ago at 07:27 PM.

  6. #6
    Senior Tuner blindsquirrel's Avatar
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    Quote Originally Posted by 12ramhemi View Post
    So I bought an EFI adjustable fuel pressure regulator. It's mounted on the return port of the fuel cell.
    And it's still non-referenced, meaning you're not using a vacuum hose going from intake to regulator?
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  7. #7
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    Quote Originally Posted by blindsquirrel View Post
    And it's still non-referenced, meaning you're not using a vacuum hose going from intake to regulator?
    No vacuum hose.This system doesn't use vacuum to regulate pressure.

  8. #8
    Senior Tuner blindsquirrel's Avatar
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    The vast majority of aftermarket adjustable regulators have the provision, which is why I asked.
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  9. #9
    Senior Tuner blindsquirrel's Avatar
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    So, now that I can look at the rest of the file...

    It's a '99 Corvette calibration? But Platform Type has been changed to F-body? Did you notice there is a note below that setting?
    [ECM] 755 - Platform Type: Indicates the Vehicle platform type. Changing this value is not recommended.(emphasis mine)
    If you need some feature that is only available in a F-body file (?) then you need to use a F-body file, not use a Corvette file changed to F-body. If you did that because of a DBC/DBW change, then put the Platform Type back to Y-body and simply change the settings in the System Options table.

    You have no MAF or just attempting to fail it for tuning? It cannot fail over into speed density unless it trips a current P0102 and/or P0103. And you have those DTCs set to No MIL Light. P0101/P0102/P0103 should be MIL on First Error. If those codes cannot set it cannot run in speed density.

    I really would not have put the entire Open Loop EQ Ratio table to all 1.00's. It needs cold enrichment. All the operating temp ranges can be 1.00, but not the whole thing like that.

    Keep in mind that changes you made to the VE when the fuel pressure was too high are hurting you now. It needed the VE cut way down because the injectors were flowing way more than they should have. Your VE has a lot less everywhere than a stock '99 LS1 file.

    (difference from stock file)
    screenshot.24-11-2022 10.27.24.png
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  10. #10
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    The stock tune was supposed to be from 2000 fbody LS1. It seems like everytime I flash a new tune, more stuff changes I didn't even touch. When I switched to the HPT OS to run SD it starting showing it was a Vette. It's dbc, not dbw. I have maf set to fail just no check engine light, and the maf codes are present in scanner. At least they did about 3 months ago . I could have sworn I reverted back to a stock ve and timing table. I will have to compare a stock tune and see what all changed that I never messed with.i also had it setup for open loop 0 to 1000 rpm and closed loop after that until PE

  11. #11
    Senior Tuner blindsquirrel's Avatar
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    Quote Originally Posted by 12ramhemi View Post
    I have maf set to fail just no check engine light
    It's set to No MIL Light. If you want it to just not turn on the light, uncheck the box. It must be able to run the MAF tests and then fail and know that it has failed and has those codes as 'Current'. To do that they should be MIL on First Error.

    There is no possible way that applying one of the custom OSes changed the file from a F-body cal with a F-body VIN to a Corvette cal with a Corvette VIN. You're getting files mixed up somewhere along the line. No other way for that to have happened.
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  12. #12
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    I got a 99 Vette tune from repository. It doesn't have as many adjustments. Mine is an 02 Fbody OS 12212156. . I may have forgot to change vin with TP and pcmhammer when I originally set this ecm up. What's weird is this an 02 S10 0411 pcm. I don't think any of that matters. It's got the correct OS options/calibrations for the 02 Fbody and not a 99 Vette. The rest of the settings I've never touched ,match the stock Fbody tune.

    I set the dtc the way you said and put the ve and timing tables back stock. I will see what it does tomorrow . Thanks for the help
    Last edited by 12ramhemi; 1 Week Ago at 05:00 AM.

  13. #13
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    Sorry didn't see the post about the vacuum referenced regulator. It has a vacuum nipple on it but I didn't think I should use the vacuum port since the returnless systems don't have a vacuum
    referenced regulator.