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

  1. #1
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    Boosting fuel pump voltage with tune-fuel system voltage min table

    Has any one else tried this. It probably only works in the E67 ECM's. I have been losing pressure in my ZL1 on top end at 13 psi boost. Looking at the CTS-V tunes and the ZR1 tunes the voltage is cranked up in the Fuel System Min table. In my ZL1 it's set at 12.5-14.5 volts and the ZR1 are 14.0-15.2 volts, then the CTS-V is 12.0-16.0 volts. The axis is not defined in HPTuners but I assume it is Airflow Mode because it runs 0-64.

    I cranked mine up to 15.5 volts in the airflow mode 36 thru 64 rows and went for a test drive and it WORKS! Voltage at wide WOT indeed went to 15.5 volts and my fuel pressure was better. I didn't want to go to far until I checked if anyone else has experimented with this. My fuel pressure could still be better because commanded is 65 psi but I got 55 psi now. But before FP was dropping to 43 psi. So this is like a Boost-a-pump built into the software. And could explain why people using a Boost-a-pump haven't been able to obtain the fuel pressure they want in the 2010+ Camaros. This table might help them, but I suspect it only works in the E67. Of course this boost the entire system voltage, not just the fuel pump and I don't want to burn anything up. But GM ran it up to 16 volts in the CTS-V so that much should be OK?

    Here is the table I'm talking about. And a shot of the WOT run with 15.5 volts.
    Attached Images Attached Images
    Bryan

  2. #2
    it's a minimum that means the regulator will not go below this voltage, the axis is fuel flow in grams/sec.

    it should work on any engine fitted with ECM controlled alternator (which is most newer ones).

    Chris...
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    This is very interesting stuff. Maybe not so good for the BAP business. I wonder if there is any downside.
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    Quote Originally Posted by Chris@HPTuners View Post
    it's a minimum that means the regulator will not go below this voltage, the axis is fuel flow in grams/sec.

    it should work on any engine fitted with ECM controlled alternator (which is most newer ones).

    Chris...
    That makes more sense. If it were Airflow Mode it would really kick in early. But you have to really get on it before the voltage climbs. Also I had it in my head about the FPCM control of the fuel pump in the E67. So if it's just alternator control then any of the new cars can bump the voltage.
    Bryan

  5. #5
    Senior Tuner Iam Broke's Avatar
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    Looking forward to trying this soon, thanks for posting.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

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    DSteck is going to kick himself in the ass for buying that 900$ alt!

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    Senior Tuner DSteck's Avatar
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    Quote Originally Posted by carlrx7 View Post
    DSteck is going to kick himself in the ass for buying that 900$ alt!
    Nah. The heat was really screwing my OEM one up. It struggled to run 13v while driving.

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    So does anyone have a reccomendation on how high I could go with voltage? Also I was checking duty cycle on the fuel pump and it stays a constant 99.6% I set the duty cycle to be 90% up to 4000 rpm then 99% after 4000rm. But it's 99 % all the time. I did set the max duty cycle to 99% Maybe the E67 only looks at that value and let's the FPCM control the duty cycle, not the PCM.
    Bryan

  9. #9
    Senior Tuner Iam Broke's Avatar
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    I had never seen anything other than 99% on my E38 LS3 after raising it so I stopped logging it a while ago. I think the FPCM takes care of it.

    If the values raise the alt output to 16 v for the entire vehicle I don't think I'd go any higher. Weather is very rainy here so I haven't been able to try it this week. Maybe tomorrow. I did blend it a bit instead of jumping from 12.5 to 16v. I added a 14.5 v row at 36 g/sec.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

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    I was going to do the same and ramp it from 12.5 to 15.0 to 16.0 volts
    Bryan

  11. #11
    Senior Tuner Iam Broke's Avatar
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    A MSD 2351 BAP goes to 22v. I dare ya!
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

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    Quote Originally Posted by Iam Broke View Post
    I had never seen anything other than 99% on my E38 LS3 after raising it so I stopped logging it a while ago. I think the FPCM takes care of it.

    If the values raise the alt output to 16 v for the entire vehicle I don't think I'd go any higher. Weather is very rainy here so I haven't been able to try it this week. Maybe tomorrow. I did blend it a bit instead of jumping from 12.5 to 16v. I added a 14.5 v row at 36 g/sec.
    Even though the scanner shows the commanded 15.5 volts I curently have set, the dash gauges aren't showing the elevated voltage. Maybe the dash gauges don't react fast enough. I need to put a voltmeter inside the car and see if the whole system sees more voltage. It would be cool if only the voltage to the fuel pump was boosted.
    Bryan

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    Quote Originally Posted by Iam Broke View Post
    A MSD 2351 BAP goes to 22v. I dare ya!
    MSD's website says specifically not to use it for a PWM fuel pump. I'd like to know for sure.
    Bryan

  14. #14
    Senior Tuner Iam Broke's Avatar
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    Don't know. Jannetty Racing on Camaro5 uses the BAP on them all the time, I found a post saying to splice it into the Red/White wire on the FPCM, not the FP. Without the wiring diagram in front of me I only assume it's the input to the FPCM.

    I'd rather use the ECU programming than adding another kludge. I have an ADM FPCM that I suspect is just a ZL-1 module with the numbers removed but it's been posted that ADM modifies them somehow to increase the output. Lots of snake oil around. I'm running that module on a ZL-1 FP but still seeing a 7psi fuel pressure drop with 67 psi commanded at 9 psi boost on E35 so it needs ~10% more fueling than 93 would.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  15. #15
    Senior Tuner DSteck's Avatar
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    I'd just buy a real fuel pump setup, but that's just me.

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  16. #16
    Senior Tuner Iam Broke's Avatar
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    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.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  17. #17
    Senior Tuner Iam Broke's Avatar
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    Quote Originally Posted by DSteck View Post
    I'd just buy a real fuel pump setup, but that's just me.
    All in due time. lol.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

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    Well I took it to 16.5 volts but it appears the best it will achieve is 15.5 volts. Still helps but it could use a little more.
    Bryan

  19. #19
    Senior Tuner Iam Broke's Avatar
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    I didn't get a chance to log mine yet with 16v commanded.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel

  20. #20
    Senior Tuner Iam Broke's Avatar
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    Logged it Fri, saw a max of 15.4x with 16v commanded. It helped some though. I like free mods.

    FP in the rail dropping from 67 psi commanded to 60 psi at the top of 3rd, Running E47 (~15% more fuel than 93) with 9 psi boost.

    IDC at 60% on the ID850's I got from DSteck.

    Need twins to go E85 I guess.
    Last edited by Iam Broke; 04-28-2013 at 11:05 AM.
    '12 Camaro T3 2SS/RS LS3 M6, SLP TVS 2300, Flex Fuel