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Thread: Boosting fuel pump voltage with tune-fuel system voltage min table

  1. #21
    Advanced Tuner silverbullet08's Avatar
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    Quote Originally Posted by Iam Broke View Post
    No real improvement on the FP today but I forgot to add the ign v to the scanner table. FML. Still dropped to 60 psi with 67 psi commanded @ 9 psi boost.

    Good news is I had the best 60-100 logged ever at 4.1 sec.
    Lol the good old cobalt 60-100 time. Crazy how you can get those cars to run close to the same time with just bolt ons and a tune. Im finishing up a TTC6 LS3 build right now. I may be hitting you up soon to talk a little about this PCM.

    ^ Good info!
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  2. #22
    Senior Tuner Iam Broke's Avatar
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    Add a thousand pounds and it gets a lot harder. lol.

    3,000 vs. 4,000 lbs.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  3. #23
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    Iam Broke, you don't have a vacuum/boost referenced fuel system, correct? If you don't, and the factory system isn't, as we know, then pressure will drop by the amount of boost you're pushing. Forgive me - I don't know your setup other than what's in your sig.

    Edit: DSteck also alluded to this in a former thread you posted within:

    http://www.hptuners.com/forum/showth...-Pressure-PIDs

    The new 2011+ Mustang GT also does not have a vacuum/boost referenced system, but it is completely mechanical (unlike the newer GMs). Thanksfully, all Mustangs from '99-'10 had a 1:1 FRPS (fuel rail pressure sensor), and '11+ GT500s still do. So just how does the 2011+ GT account for "droop"? It does this by a table called "Fuel Rail Pressure" in the Returnless Fuel Pump section. It has to be tuned properly when adding boost to keep injector pulse-width in check. Since injector characteristics are different at various pressures, if this table is adjusted properly, and the proper injector data is used, then the airflow model remains true. Here's how the table looks factory:

    Code:
    Fuel Flow  Rail Pressure
    3.00 	   55.9000
    2.50 	   57.0000
    2.00 	   57.7000
    1.39 	   57.9000
    0.80 	   58.7999
    0.00 	   59.2999
    The system in your Camaro accounts similarly, but obviously more precise (since it's electronically measured), in that based on actual measured fuel pressures the injector characterization remains true, thus your airflow model does, as well. The only downside to this is that since it's not a 1:1 boost referenced system, then one with a boosted setup would obviously need a larger injector, comparatively speaking, to compensate for the loss of flow.

    One other thing, you're commanding 67 psi, but the ZL1, like the CTS-V, has a blow-off at 65.x psi (4.5 bar). Do you have a modded blow-off in the tank? I know some have put in spacers/washers to get around this limitation.

    I hope this helps!
    Last edited by RWTD; 04-30-2013 at 04:49 PM.
    Formerly known as RWTD

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  4. #24
    Senior Tuner Iam Broke's Avatar
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    I log injector differential pressure by subtracting map & baro from rail (or line) pressure. Of course in a perfect system my 8.7 psi boost would mean a inj diff of 58 psi.

    No, I have not modified the relief in the tank, but I have proof via logs it will hold my commanded of 66.7 psi. Prob manufacturing differences that I am taking advantage of.

    It is not a boost referenced system but the ID850 inj data tracks the fuel pressure drop quite well.

    Thanks for your input. I suspect a substantial pressure drop going to E85 from E60 but since my IDC is still in the mid 60's I'm hoping for 80% IDC.

    Next winter it'll get more fuel. If it drops painfully low on E85, I'll run E47 for this season. As long as inj pressure diff stays over 3 bar (where the inj are rated as 850's) I'll most likely run E85.
    Last edited by Iam Broke; 04-30-2013 at 06:25 PM.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  5. #25
    Senior Tuner DSteck's Avatar
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    You sound like just the kind of person who should use a flex fuel sensor!

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  6. #26
    Senior Tuner Iam Broke's Avatar
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    I know.......

    Pretty bad when I have a custom pid to calculate room in the tank and an ethanol calculator link on my smartphone.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  7. #27
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    Quote Originally Posted by Iam Broke View Post
    Thanks for your input. I suspect a substantial pressure drop going to E85 from E60 but since my IDC is still in the mid 60's I'm hoping for 80% IDC.

    Next winter it'll get more fuel. If it drops painfully low on E85, I'll run E47 for this season. As long as inj pressure diff stays over 3 bar (where the inj are rated as 850's) I'll most likely run E85.
    Just to give you an example on the last ZR1 I tuned, on E10, at the top of the pull, "Requested Fuel Pressure" was 87 psi, and "Inj Delta Pressure" was 71.6 psi, and on E85, it was 87 psi and 58.4, respectively. That should give you some data to at least calculate some rough numbers with. This car was using "shorty" SD 60s, which are approx. 91.5# at 87 psi.
    Last edited by RWTD; 04-30-2013 at 07:17 PM.
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  8. #28
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    10 years later, can we get this axis labeled properly finally???
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  9. #29
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    Quote Originally Posted by GrannySShifting View Post
    10 years later, can we get this axis labeled properly finally???
    You need this for the Vo?

    P.s. The axis still isn?t properly labeled? SMH!
    Formerly known as RWTD

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  10. #30
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    Vo?

    And no, nothing gets fixed around here it seems. I still run into gen3 stuff when you hit the unlock button in bi-directional controls it locks the effing converter!
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  11. #31
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    Quote Originally Posted by RWTD View Post
    You need this for the Vo?
    Peep my post about ZL1 pump in NA E85 if you get the chance... my brain is shot
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere