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Thread: HELP!!!! 2014 mustang won't even start when cold!

  1. #1
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    HELP!!!! 2014 mustang won't even start when cold!

    New to forum and never used HP tuners before. The story goes my brother bought a twin turbo 2014 mustang 5.0 and it makes insane power and runs great during the summer. It was tuned with HP tuners and he as a labtop and the interface that came with it. We live in Minnesota and yesterday it was in the 30's and it started and ran fine. It was only started to make sure it would start if we rented a trailer for Sat. So we rented the trailer. We of course don't drive hot rods in the winter but today we wanted to move it to my shop an hour away to do some work over the winter. We went to start it to put it into an enclosed trailer and it was a nightmare to say the least. It has bigger injectors in it and stuff and I'm guessing whoever tuned it didn't tune it for the bigger injectors in the cold weather, I'm not sure. It was 4 degrees today and when we did get it to start it was with the fuel pump unhooked and then turn it on once it was running and try and keep it running. Once it was running the AFR was 9.0:1 and fuel was running out of exhaust and it didn't have enough power to move out of its own way and if you let it idle it was so rich it died. I pulled up HP tuners on his computer but I have literally never touched it before so had no idea what to do? We unhooked the MAF and IAT and got it to run, still idled at 9.0:1 but as soon as you touched the gas it was 20:1, so as you can see it took use about 3 hours to get it in the trailer, that shoulda taken about 2 minutes. It runs great in the summer and drives fine and came with dyno charts something to the tune of 863 rwhp, but can anyone tell me what I need to do change to make it run when its in the minnesota winter, it doesn't need to be perfect just start and run and drive itself in and out of a trailer as in minnesota from November- April our stuff pretty much stays in a shed.

  2. #2
    do you have check engine light on? tuned on e85 or pump gas

  3. #3
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    I would assume this is on E85?

    Its very common to have cold start issues on E-85 and its not that the tuner didn't tune it its that they cannot tune it for a cold start unless they attempted to start it in that condition which would never happen on a dyno. Cold starts are always approximated when your dyno tuning unless you keep the car to cold start it the next morning. Again though it has to be the temp your experiencing the issues at otherwise its useless.

    In any case theres two separate fueling algorithms at play. Base fuel and the base fuel cranking modifiers.

    From what you describe it sounds like your base fuel needs to be reduced significantly. Go to your startup enrichment subtractor tables and reduce the enrichment at the cells in that 4 degree range. Since its fine at 30 degrees you can interpolate values closer to those at the lower temps.
    O&E Speed Shop - 2333 Aberdeen St. Kenner, LA
    EFI Calibrator - decipha @ EFIDynoTuning
    http://www.efidynotuning.com/tune.htm

  4. #4
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    It is tuned to make max power on e85 but we were told we could run it on e85 or 91 as it has a fuel sensor in it and it will limit boost with pump gas. He normally runs it on e85 but drains it and and puts in pump gas for the winter so it doesn't sit with e85 in it as with our winters sometimes it sits for 6 months. So currently it is running on 91 octane. Thanks decipha I'll see if I can find those tables and play with it as I have never worked with hp tuners before, although I'd sure like to learn. The first time you open the program up though its so overwhelming I didn't even know where to start.

  5. #5
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    fuel map.jpg

    Is this the fuel map you are talking about? To answer the other question, no we didn't have a check engine light until we unhooked the MAF sensor in any attempt to make it drive 50 feet to the trailer.

  6. #6
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    Just post the tune...

  7. #7
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    Here is the tune in the car. The car started up and ran great when it was back in a 50* shop. Once pulled back outside, it went extremely rich again within a few minutes. I have looked at the open loop cold tables and they appear to be good.

    Base Tune 10PSI.hpt

  8. #8
    reactivate O2 sensor heater and return the fuel cranking vs ECT to stock by setting all table to 1. if not work with you better to post datalog for issue

  9. #9
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    The tune itself is set up to run pump gas only. Not E85.

    Re-enable the O2 sensor heaters for the front like was mentioned. The signs you mention are common for bad O2's among a few other possibilities.
    I'm also wondering the reason behind the changing of your engine size to 4.3L???

  10. #10
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    It appeared to me also that it was set for gas but figured they just added extra fuel with the injectors settings. The car was all setup for e85 and just retuned right before I bought it. I cannot answer why the tuner entered what he did. Supposedly a reputable tuner but I havent been very impressed with him. It will be getting retuned in the spring.

  11. #11
    Tuner in Training
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    It appears the tuner tried to scale the file, why, who knows.

    This tune is not good, at all.

  12. #12
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    What injectors are installed on the car?
    You said the car came with a laptop and hptuners? So you can make the corrections needed.

  13. #13
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    The car has id1300 injectors. And yes I do have a laptop and MPVI so I can make changes thankfully.

  14. #14
    Advanced Tuner mbray01's Avatar
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    Im just curious, under full throttle, does the throttle body stay open, does it stay in optimum power mode.
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    15yr Master Tech.
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  15. #15
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    In Bazil, cars have a small aux fuel tank (pure gasoline) for cold starting. As ethanol creates cold start issues.
    You may not have any problems.