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Thread: 2015 Mustang E85 - No start when hot

  1. #1
    Tuner Kryckter's Avatar
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    2015 Mustang E85 - No start when hot

    I have a 2015 Mustang with the Hellion twin kit. Car was originally dialed in on pump gas and then a return style fuel system with fuel rails was added and switched to E85. The tune stayed pretty much the same besides stoich value and timing when switching to E85.

    Since the switch to E85 the car will not start once it gets hot. I can make some WOT pulls and cruise for a few minutes to let the car cool. I park and turn it off. If I wait 5 minutes or so the car will not start. I will then need to pop the hood and wait 15-20 minutes before the car starts. When it doesn't start it just cranks over and over. Doesn't even attempt to start. I can do that several times. But when it finally starts it starts up like nothing ever happened. Doesn't spit, studder or slow start...

    I dont have a log in VCM Scanner of this doing this. The log shows that it gets no timing when it wont start. The timing will stay at -2 or so instead of the 3 degrees or so when it cranks and actually starts. I've tried some changes to the cranking spark act vs ect table with no luck.

    Weird part and maybe a clue, if I re-flash the computer with the same tune it will start up just fine even if I don't let the car cool. Is there some switch or table that is an overtemp protection of sort?

    Thoughts? I can post a SCT log if someone wants it and I will try to get a log with the VCM scanner soon. I know its frowned upon but I probably wont post the tune since its not really my tune and was dialed in from another tuner. I can check and post certain tables if needed though. THANKS!!!
    Last edited by Kryckter; 10-01-2015 at 09:20 AM.
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  2. #2
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    Make sure all of the multipliers for the injectors are set to 1.

  3. #3
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    Quote Originally Posted by txcharlie View Post
    Make sure all of the multipliers for the injectors are set to 1.
    They are not. All 4 (high, low, breakpoint and offset have values) - The first 3 start around .70 and go to 1.2ish and the last is .9 to 1.1.
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  4. #4
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    Need to change to 1 with a return system.

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    Quote Originally Posted by txcharlie View Post
    Need to change to 1 with a return system.
    Interesting... All 4 tables? Any effect on WOT AFR by changing all those to 1?

    Would you still want to change it to 1 on a vacuum/boost referenced regulator?
    Last edited by Kryckter; 10-01-2015 at 03:24 PM.
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  6. #6
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    Makes no difference if boost reference or not. I believe the multipliers are used to determine the amount of voltage the pcm supplies to the pump in a stock returnless system. Return system runs the same voltage all the time.
    The only change for boost reference would be in the inferred rail pressure table. It would be set to your base pressure at idle with vacuum line disconnected.
    I had issues with my setup using boost reference. It was too inaccurate. Fuel trims all over the place. I now run without boost reference.

  7. #7
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    Which injector are you using? Leave it boost referenced to maintain effective pressure on the injectors. Your multipliers need be set to one.
    Last edited by BNA; 10-01-2015 at 06:45 PM.

  8. #8
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    Quote Originally Posted by BNA View Post
    Which injector are you using?
    Deatschwerks 95lb

    I had also used these on my pump gas setup for about 2 months as well that did not do this no start issue... (if that helps at all)
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  9. #9
    Tuner Kryckter's Avatar
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    I did find the log I have from VCM scanner of it not starting

    No Start.hpl
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  10. #10
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    Attached is the calibration data for return fuel system with a base pressure of 39.15 or 55 psi. You need to set the base pressure with vacuum line off pressure regulator, once set reinstall vacuum line.


    Injector.jpg

  11. #11
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    What are the fuel trims when car is running?

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    Quote Originally Posted by Kryckter View Post
    Deatschwerks 95lb

    I had also used these on my pump gas setup for about 2 months as well that did not do this no start issue... (if that helps at all)
    Was it a return system then?

  13. #13
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    So I tried the new injector data. Mine was not off from their newly posted stuff. No change on hot start, still failed to start...

    Quote Originally Posted by BNA View Post
    What are the fuel trims when car is running?
    The idle fuel trims are close to 0. Bouncing from -2 to 2. If they favor any direction it would be maybe 2-4. Cruising the trims are probably 6 to 8 bouncing around. All in all the trims stay on the positive side...

    Quote Originally Posted by txcharlie View Post
    Was it a return system then?
    It was not a return system then, stock fuel system with just the injectors and a JMS FuelMax.
    Last edited by Kryckter; 10-01-2015 at 09:17 PM.
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  14. #14
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    What is you base fuel pressure set too? May just need to start adjusting cranking fuel.

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    Quote Originally Posted by BNA View Post
    What is you base fuel pressure set too? May just need to start adjusting cranking fuel.
    The base fuel pressure is at 55psi. I have also had it at 60psi with no changes...

    I feel it is spark related, like no spark. But I am up for trying anything. Any pointers on what to try for cranking fuel?
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  16. #16
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    Try increasing your crank fuel mass.

  17. #17
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    Quote Originally Posted by BNA View Post
    Try increasing your crank fuel mass.
    I will give it a try... So for the warmer temps, do you think an increase in about 10%?
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  18. #18
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    Quote Originally Posted by BNA View Post
    Try increasing your crank fuel mass.
    I tried this with no luck...

    Still seems to be timing related. It locks the timing to -1/-2 when it does the weird no start problem. If I disconnect the battery or re-flash with the same tune it will start right up...
    2015 Mustang A6
    Hellion Twin Turbo
    Fore Innovations Return Fuel System
    806rwhp / 786rwtq

  19. #19
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    Does the timing change after the reflash too? When it does start what are the Lambda readings ?
    Last edited by BNA; 10-13-2015 at 09:08 PM.