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Thread: 2015 Mustang GT Twin Turbo knock on dyno 6psi?

  1. #1

    2015 Mustang GT Twin Turbo knock on dyno 6psi?

    So I finally got my car to the dyno today and I am a bit confused. I am running 6 psi on twin precision 6266 turbos which I felt was very conservative. I got on the dyno today and realized that my computer is pulling close to 6 degrees out around 5300 RPM, my timing is only set at 20 max here. Also, around 4200 is pulls about 3 degree and you can clearly notice in the dyno graph where it pull because of the dips. The car seemed to die off after 6k RPM so I never pulled the car higher than that due to having a fear that something may be wrong. On the last pull I did turn off the knock retard and the car picked up in all fields but still seemed faily low for HP. I have attached logs from a few pulls they were all done in 5th gear on the dyno. Can anyone take a look at my logs and tune to see if I am clearly missing anything here?

    Current Tune
    DynoKnockTune.hpt

    Logs
    lesstimingretard.hpl
    knockoff.hpl
    knockretardoff.hpl
    knockremoved.hpl

    Dyno Sheet
    123_1(1).jpg

    Boost Level
    123_1.jpg

  2. #2
    Senior Tuner veeefour's Avatar
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    Your MAF curve is not interpolated for the power you are making. Where the MAF sensor is located? Pipe or IC? Pipe ID?

    You are picking knock at 3500rpm in each pull you make.


    You need to log more pids like injector duty and pulse, brake torque, IRMC, VCT "actual" angles, TCC slip. Remove all SAE parameters.

  3. #3
    Quote Originally Posted by veeefour View Post
    Your MAF curve is not interpolated for the power you are making. Where the MAF sensor is located? Pipe or IC? Pipe ID?

    You are picking knock at 3500rpm in each pull you make.


    You need to log more pids like injector duty and pulse, brake torque, IRMC, VCT "actual" angles, TCC slip. Remove all SAE parameters.
    The MAF is located in the intercooler pipe about 40 cm from the throttle body. Its inside of a 4 inch pipe.

    Are you saying the MAF curve is causing the knock? I can see the knock but I'm confused as to what's causing it.

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    I haven't seen the log or tune yet because I'm not at computer but seems like most turbo Coyote I come across have a pipe making contact somewhere causing false knock. First thing I would check is to see if there is anywhere obvious you could have contact being made on your setup. Keep in mind things shift around a good bit during a pull.

  5. #5
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by imrex613 View Post
    The MAF is located in the intercooler pipe about 40 cm from the throttle body. Its inside of a 4 inch pipe.

    Are you saying the MAF curve is causing the knock? I can see the knock but I'm confused as to what's causing it.
    Not the best place for MAF - it's tune-able but difficult.

    Yes, you can have rich or lean detonation. Your MAF curve is nowhere near to be usable.

    You can't scale your MAF for turbo just like you do with N/A. You will hit much lower period counts while boosted.

    Log your IMRC - not sure you have them locked or not but hey can flap out of control or be broken already.

  6. #6
    Quote Originally Posted by veeefour View Post
    Not the best place for MAF - it's tune-able but difficult.

    Yes, you can have rich or lean detonation. Your MAF curve is nowhere near to be usable.

    You can't scale your MAF for turbo just like you do with N/A. You will hit much lower period counts while boosted.

    Log your IMRC - not sure you have them locked or not but hey can flap out of control or be broken already.

    What would be the IDEAL location? I could easily move it if need be.

    Are you saying my MAF curve is causing my knock? I did multiple 30min plus drives and tuned my MAF curve until my STFT + LTFT was within +/- 2. Here is a SS of them on one of my logs

    mafcurve.png

    I just assumed they were off during these pulls since I turned the car off after each one and didn't let the car run long before each pull. If my curve is that far off is there a different formula I should be using for boost?

    I understand rich and lean detonation but my AFRss were mid to high 11s that seems like a safe range.

    I know locking the IMRC is recommended on boost applications but I did not think it was necessary if there weren't any codes. They are currently not locked and functioning like from the factory. I will add that to my parameters to log.

  7. #7
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    You would be surprised how 5-6% in the right spot of the MAF transfer, will help with detonation right as the turbo is spooling. Keep in mind once detonation happens, it can take a lot of spark being pulled to stop it, if your load was far off. Just a little higher MAF value can put you in the right spot on your spark tables, compared to the wrong spot. In your case the fuel trims are saying increasing 160u-140u of your MAF transfer 5-6%. Then there are a few, jittery spots you just need to flatten out. You seriously don't want fuel trims going from lean to rich as the air flow is rapidly increasing and you go from no boost into boost. This will not represent the actual load well, and put you at high risk of running into detonation. Either have fuel trims lean to lean, rich to rich, or rich to lean during the turbo spool, Or best option just get it as dialed in as possible. Some MAF signals are just horrible to work with and you have to deal with the error it leaves on the table.

    Knocktune MAF correction.PNG
    Last edited by murfie; 10-29-2019 at 05:17 AM.

  8. #8
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by murfie View Post
    You would be surprised how 5-6% in the right spot of the MAF transfer, will help with detonation right as the turbo is spooling. Keep in mind once detonation happens, it can take a lot of spark being pulled to stop it, if your load was far off. Just a little higher MAF value can put you in the right spot on your spark tables, compared to the wrong spot. In your case the fuel trims are saying increasing 160u-140u of your MAF transfer 5-6%. Then there are a few, jittery spots you just need to flatten out. You seriously don't want fuel trims going from lean to rich as the air flow is rapidly increasing and you go from no boost into boost. This will not represent the actual load well, and put you at high risk of running into detonation. Either have fuel trims lean to lean, rich to rich, or rich to lean during the turbo spool, Or best option just get it as dialed in as possible. Some MAF signals are just horrible to work with and you have to deal with the error it leaves on the table.
    As always Murf comes with a solid academic explanation - I have nothing more to add

    @imrex613
    Log IMRC see if it operates properly. Closed IMRC will cause knock under boost. I don't think you have something hitting mechanically because your knock starts regularly at the same spot.

    MAF transfer is everything in those cars - you can screw spark, SD model or torque model ECU still have some wiggle room but if MAF is wrong everything else is wrong.

    This is your MAF curve right now:
    your maf.jpg

    This is my twin turbo tune:
    my maf maf.jpg

  9. #9
    Quote Originally Posted by murfie View Post
    You would be surprised how 5-6% in the right spot of the MAF transfer, will help with detonation right as the turbo is spooling. Keep in mind once detonation happens, it can take a lot of spark being pulled to stop it, if your load was far off. Just a little higher MAF value can put you in the right spot on your spark tables, compared to the wrong spot. In your case the fuel trims are saying increasing 160u-140u of your MAF transfer 5-6%. Then there are a few, jittery spots you just need to flatten out. You seriously don't want fuel trims going from lean to rich as the air flow is rapidly increasing and you go from no boost into boost. This will not represent the actual load well, and put you at high risk of running into detonation. Either have fuel trims lean to lean, rich to rich, or rich to lean during the turbo spool, Or best option just get it as dialed in as possible. Some MAF signals are just horrible to work with and you have to deal with the error it leaves on the table.

    Knocktune MAF correction.PNG
    Ok this makes perfect sense now. I see exactly how my curve was off comparing those two charts. The only other question I have is how did you come up with those numbers? Was it just a matter of seeing how my curve was out of whack and correcting those areas by lowering/raising or is there a forumlua behind it? Once I plug those in should I go back to datalogging STFT + LTFT or is there another method of doing so? Sorry if the questions sound silly but I am really trying to learn this system.

    Quote Originally Posted by veeefour View Post
    As always Murf comes with a solid academic explanation - I have nothing more to add

    @imrex613
    Log IMRC see if it operates properly. Closed IMRC will cause knock under boost. I don't think you have something hitting mechanically because your knock starts regularly at the same spot.

    MAF transfer is everything in those cars - you can screw spark, SD model or torque model ECU still have some wiggle room but if MAF is wrong everything else is wrong.

    This is your MAF curve right now:
    your maf.jpg

    This is my twin turbo tune:
    my maf maf.jpg
    IMRC will be added to my logs for the future now

  10. #10
    Senior Tuner veeefour's Avatar
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    Most people are use to change the airflow values only because this how they teach you - correct approach for N/A tuning. In boosted applications it's sometimes better to change the period values.

    Try to keep everything smooth as possible, fill those huge leaps, try to cover the period values your car is actually seeing.

  11. #11
    Quote Originally Posted by veeefour View Post
    Most people are use to change the airflow values only because this how they teach you - correct approach for N/A tuning. In boosted applications it's sometimes better to change the period values.

    Try to keep everything smooth as possible, fill those huge leaps, try to cover the period values your car is actually seeing.
    Would you be willing to elaborate on this for me? I fully understand you are a tuner and don't want to give the answer out for free but I would really like to understand this. If not could you atleast provide where I might he able to research this I've done numerous searches on everything and can't find info about changing the period values for boost.

  12. #12
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    Just graph it, OR look at the chart vs time and see the trend of STFT vs MAF period if the graphs are not being populated with enough data. Stay away from SAE PID's whenever possible to get faster polling rates.
    You can look at sections of the chart like from 140-160u period and see that you can add 5% there. Then look at your transfer and add 5% to the cells that closest represent that section. 157.6- 139.5 is essentially the same thing as 160-140u.
    When looking at the transfer in the editor, you should be looking at it in vertical split view, just like some other tables are easier to view in 3d view.
    Currently you have four cells that define this section of the transfer. Also currently From 350u-150u its seems to define the most "bent" part of the curve. Above that and below that are much closer to straight lines. You need more points to define a good curve, compared to defining a line. This is where moving your defined period values can be optimized. More resolution for parts of the transfer that needs it.

    Three out of the four logs you posted show nearly the same trend. The fourth your fuel trims seems to come in a little slow, I wouldn't look too much into it.

    Knock removed.PNG

    lesstiming retard.PNG

    Knock retard off.PNG

    As an example of wasted resolution, from the top of your MAF transfer, a linear trend line fits better than a power trend line. An exponential trend line is only 1% better than a linear, and once things are smoothed, a linear may actually fit better. The fact that these are all with in 2% R^2 is all that really matters, and it's all you need to know to decide if you want more or less period points defining that part of the transfer.

    Top of MAF linear vs power.PNG

    Compare that to the middle of the transfer where R^2 can be 15-20% different between a linear trend and exponential trend. This is where you need the most cells to define the transfer the best.

    Middle of MAF linear vs exponential.PNG
    Last edited by murfie; 10-30-2019 at 12:09 AM.

  13. #13
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by imrex613 View Post
    Would you be willing to elaborate on this for me? I fully understand you are a tuner and don't want to give the answer out for free but I would really like to understand this. If not could you atleast provide where I might he able to research this I've done numerous searches on everything and can't find info about changing the period values for boost.
    I think Murfie covered everything.

    The way I do this is to make a histogram with period in relation to RPM - average everything with cell hit count to determine what period you are seeing the most.
    Now you have your average period values copy them to your tune and stat dialing the trims with STFT like you always do.

    Recheck everything make sure period counts have a good transition, you can't have any huge leaps as pictured below. Boost will not tolerate this.

    Clipboard01.jpg

  14. #14
    Quote Originally Posted by murfie View Post
    Just graph it, OR look at the chart vs time and see the trend of STFT vs MAF period if the graphs are not being populated with enough data. Stay away from SAE PID's whenever possible to get faster polling rates.
    You can look at sections of the chart like from 140-160u period and see that you can add 5% there. Then look at your transfer and add 5% to the cells that closest represent that section. 157.6- 139.5 is essentially the same thing as 160-140u.
    When looking at the transfer in the editor, you should be looking at it in vertical split view, just like some other tables are easier to view in 3d view.
    Currently you have four cells that define this section of the transfer. Also currently From 350u-150u its seems to define the most "bent" part of the curve. Above that and below that are much closer to straight lines. You need more points to define a good curve, compared to defining a line. This is where moving your defined period values can be optimized. More resolution for parts of the transfer that needs it.

    Three out of the four logs you posted show nearly the same trend. The fourth your fuel trims seems to come in a little slow, I wouldn't look too much into it.

    Knock removed.PNG

    lesstiming retard.PNG

    Knock retard off.PNG

    As an example of wasted resolution, from the top of your MAF transfer, a linear trend line fits better than a power trend line. An exponential trend line is only 1% better than a linear, and once things are smoothed, a linear may actually fit better. The fact that these are all with in 2% R^2 is all that really matters, and it's all you need to know to decide if you want more or less period points defining that part of the transfer.

    Top of MAF linear vs power.PNG

    Compare that to the middle of the transfer where R^2 can be 15-20% different between a linear trend and exponential trend. This is where you need the most cells to define the transfer the best.

    Middle of MAF linear vs exponential.PNG
    Thanks I will take this info and work on my curve then post once it is redone.

  15. #15
    Quote Originally Posted by veeefour View Post
    I think Murfie covered everything.

    The way I do this is to make a histogram with period in relation to RPM - average everything with cell hit count to determine what period you are seeing the most.
    Now you have your average period values copy them to your tune and stat dialing the trims with STFT like you always do.

    Recheck everything make sure period counts have a good transition, you can't have any huge leaps as pictured below. Boost will not tolerate this.

    Clipboard01.jpg
    Thanks,

    What program are you using to chart with the plots as you posted the pic with the highlighted red circles that gives a much better look at the curve? Also, just to be clear what I setup was MAF Period vs RPM histogram. The numbers seem to vary by RPM so my next question is should I average the entire period to determine my new values? Hopefully my question makes sense I am adding a SS of my graph to help

    histogram.png

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  17. #17
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    Quote Originally Posted by imrex613 View Post
    The MAF is located in the intercooler pipe about 40 cm from the throttle body. Its inside of a 4 inch pipe.

    Are you saying the MAF curve is causing the knock? I can see the knock but I'm confused as to what's causing it.
    in a straight section of pipe?

  18. #18
    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by imrex613 View Post
    The MAF is located in the intercooler pipe about 40 cm from the throttle body. Its inside of a 4 inch pipe.
    Sorry, I was reading too fast - I thought you have your MAF on the IC but you have it in 4 inch pipe far away from TB which is 100% correct.

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    Quote Originally Posted by veeefour View Post
    Sorry, I was reading too fast - I thought you have your MAF on the IC but you have it in 4 inch pipe far away from TB which is 100% correct.


    Just have to watch the MAF isn't located just after a bend in the tubing. It can be hell to tune from my understanding

  20. #20
    Quote Originally Posted by Speedtospare View Post
    Just have to watch the MAF isn't located just after a bend in the tubing. It can be hell to tune from my understanding
    https://ibb.co/rxJBhT8

    This is my MAF location, ignore the vacuum line. From that it goes to a 90* silicone elbow off the TB (the side with the vacuum ports)