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Thread: Help with turbo Coyote

  1. #21
    Tuner in Training kareltuning's Avatar
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    Quote Originally Posted by veeefour View Post
    You still have some limiters in your tune - that's why it's closing the throttle. This will not fix the power dip tho - you need to rework your MAF transfer for that.

    Attachment 96170
    Thank you, the throttle is closing at 7400 like it is supposed to. I don't want to rev any higher. My problem is before that.

  2. #22
    Tuner in Training kareltuning's Avatar
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    Quote Originally Posted by veeefour View Post
    Correct and not correct at the same time, your tune is not ready for anything above load 1.8. YourMAF transfer is bad has holes between points - ECU enters that gap and you think you have valve float while you do not.
    I will check the max load, but I don't really plan on doing more than that. I have checked the maf and I don't see any holes between points. Are you sure you are looking at my file? I have attached screenshots of the transfer function

    MAF VCM.PNG MAF Transfer zoom.PNG

  3. #23
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by kareltuning View Post
    Thank you, the throttle is closing at 7400 like it is supposed to. I don't want to rev any higher. My problem is before that.
    And there's some hysteresis...

  4. #24
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by kareltuning View Post
    I will check the max load, but I don't really plan on doing more than that. I have checked the maf and I don't see any holes between points. Are you sure you are looking at my file? I have attached screenshots of the transfer function

    MAF VCM.PNG MAF Transfer zoom.PNG
    Sure, imagine 3,5" MAF housing, a gap between period 80 and 85 makes 100hp...

  5. #25
    Tuner in Training kareltuning's Avatar
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    Quote Originally Posted by murfie View Post
    Maxing out the injectors for the pressure you have them at.

    9.7 stoich

    .75 WOt lambda

    that is a 7.275 target wot ratio.

    (from your HPT file)1.44 lb/min * 8 injectors= 11.52 lb/min max.

    11.52* 7.275 ratio= 83.8 lb/min air flow max. The same flow right when you are at ~6700RPM.


    Use the 55psi injector values from DW, set your base rail pressure to 55psi instead of 45psi, if your pump/s can maintain the flow needed for that higher pressure this should help your injectors out a lot. It would move the limit up to 98.9lb/min. commanding a leaner WOT lambda would help some too. You are getting in the COT territory.

    At the least, when you do figure out whats restricting the airflow, be it throttle closing or "valve float', You won't max the injectors out completely. They work best when kept around 80% or less.
    Target horsepower initially was around 850 so I figured I could run 3bar pressure since the drivability is like stock. The o2's (mounted pre-turbo) match the downpipe installed wideband when there is no boost, then I guess backpressure or something else makes them read richer under boost and I did not want the closed loop leaning out the car so that's why the rich target. Actual AFR under wot was 11.5 the whole pass when measured in dyno and with wideband gauge. The alternator was dropping voltage during that run and was later discovered when I logged voltage in another session so maybe the pumps weren't working at 100%. With the new alternator I was able to reduce duty by about 20% while still running rich afr but the problem persisted.

    At 4psi it did not fall off, at 7 psi it started falling off at about 7200 and at 10 it does what the graph shows. I will go by the dyno and take pictures of these runs and post them later since it was very late and I was frustrated

    If the customer decides to up the power I will recommend either higher pressure of bigger injectors. I just like running the lowest pressure I can on turbo cars with electric fuel pumps since their flow is reduced with pressure. But definitely your input on how to calculate the max flow is greatly appreciated. Thank you so much.


    I apreciate you taking your time with this issue. Everything you write helps a lot.
    Last edited by kareltuning; 02-01-2020 at 10:49 AM.

  6. #26
    Tuner in Training kareltuning's Avatar
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    Quote Originally Posted by veeefour View Post
    Sure, imagine 3,5" MAF housing, a gap between period 80 and 85 makes 100hp...
    I added more resolution points since that pass and ended up with roughly the same shape and still had the same problem.

    MAF New map.PNG MAF New map VCM.PNG

  7. #27
    Tuner in Training kareltuning's Avatar
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    Quote Originally Posted by murfie View Post
    Maxing out the injectors for the pressure you have them at.

    9.7 stoich

    .75 WOt lambda

    that is a 7.275 target wot ratio.

    (from your HPT file)1.44 lb/min * 8 injectors= 11.52 lb/min max.

    11.52* 7.275 ratio= 83.8 lb/min air flow max. The same flow right when you are at ~6700RPM.


    Use the 55psi injector values from DW, set your base rail pressure to 55psi instead of 45psi, if your pump/s can maintain the flow needed for that higher pressure this should help your injectors out a lot. It would move the limit up to 98.9lb/min. commanding a leaner WOT lambda would help some too. You are getting in the COT territory.

    At the least, when you do figure out whats restricting the airflow, be it throttle closing or "valve float', You won't max the injectors out completely. They work best when kept around 80% or less.
    Also I forgot, this car has a fender exhaust, no cats to worry about. Single turbo.

  8. #28
    Tuner in Training kareltuning's Avatar
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    For anyone reading this thread. The problem turned out to be valve float. Installed valve springs and with no other changes car revved cleanly and made power on the dyno to 8100rpm.

  9. #29
    Advanced Tuner small tuner's Avatar
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    good job, what valve springs , pac or trick flow
    Last edited by small tuner; 05-21-2020 at 09:59 AM.
    Turbocharged COYOTE

    PM for E tune / Remote Tuning
    [email protected]

  10. #30
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by kareltuning View Post
    For anyone reading this thread. The problem turned out to be valve float. Installed valve springs and with no other changes car revved cleanly and made power on the dyno to 8100rpm.
    You "patched" your real problem with stiffer valve springs which is very common...but this is not where your real problem lies..trust me...

  11. #31
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    Veefour, are you saying you have seen this problem before and successfully fixed it with tuning?