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Thread: 2016 Challenger Scat Pack A8 tip in bog on e85

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    2016 Challenger Scat Pack A8 tip in bog on e85

    Hi, I am trying to help my brother out with his Scat Pack A8.

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    Ported IM/TB
    Hell cat injectors
    Catless mids
    JLT CAI
    E85

    So he had the car remote tuned by somebody(forget the name) using a Diablo for straight E85. The car starts fine on it's own then stumbles and shuts off. 2-3 attemtps and it will finally hold idle. Next issue is if you give it any tip in throttle, the engine stumbles and dies. If you can get the rpm up to around 2k rpm, then it will rev and run fine. Fuel trims are +/-2%, so I don't think it's fueling. It seems airflow, timing, or torque related. I notice when I give it throttle the timing jerks negative then it stumbles. The tuner has provided several revisions and it still does the same thing. Fwiw it ran fine on 93 octane tune.

    Thanks for any and all advice! I am fairly competent with GM gen 3/4/5 but Dodge looks to be a bit more complex.


    2016ChallengerDiablotune.1.hpt

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    Quote Originally Posted by 1scls1z View Post
    Hi, I am trying to help my brother out with his Scat Pack A8.

    Mods:

    Ported IM/TB
    Hell cat injectors
    Catless mids
    JLT CAI
    E85

    So he had the car remote tuned by somebody(forget the name) using a Diablo for straight E85. The car starts fine on it's own then stumbles and shuts off. 2-3 attemtps and it will finally hold idle. Next issue is if you give it any tip in throttle, the engine stumbles and dies. If you can get the rpm up to around 2k rpm, then it will rev and run fine. Fuel trims are +/-2%, so I don't think it's fueling. It seems airflow, timing, or torque related. I notice when I give it throttle the timing jerks negative then it stumbles. The tuner has provided several revisions and it still does the same thing. Fwiw it ran fine on 93 octane tune.

    Thanks for any and all advice! I am fairly competent with GM gen 3/4/5 but Dodge looks to be a bit more complex.


    2016ChallengerDiablotune.1.hpt
    The first glaringly obvious problem is that the fuel stoich values are all still set for gasoline. The fact that those are setup wrong means the power enrichment adders are also set incorrectly. And the fact that you're only seeing fuel trims near the 2% range likely means the injector fuel mass delivery model has been hacked to compensate for the lack of modifying the stoich values in order to get trims in an acceptable range, and is likely completely botched.

    Best bet at this point is to find a stock tune file and do a comparison between what you currently have, and stock. I'd start out with a stock injector fuel mass delivery model, change the stoich values for e85, change the Power Enrichment values for your desired lambda at WOT, then you can either take the Neural Network tuning method of tweaking the fuel mass delivery model to achieve the desired results, or you can turn neural network off and tune via the VE tables.

    Edit: Use the fuel mass delivery model from a Hellcat calibration for your injector model as a base since it's running hellcat injectors.
    Last edited by B00STJUNKY; 4 Weeks Ago at 10:05 PM.

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    Quote Originally Posted by B00STJUNKY View Post
    The first glaringly obvious problem is that the fuel stoich values are all still set for gasoline. The fact that those are setup wrong means the power enrichment adders are also set incorrectly. And the fact that you're only seeing fuel trims near the 2% range likely means the injector fuel mass delivery model has been hacked to compensate for the lack of modifying the stoich values in order to get trims in an acceptable range, and is likely completely botched.

    Best bet at this point is to find a stock tune file and do a comparison between what you currently have, and stock. I'd start out with a stock injector fuel mass delivery model, change the stoich values for e85, change the Power Enrichment values for your desired lambda at WOT, then you can either take the Neural Network tuning method of tweaking the fuel mass delivery model to achieve the desired results, or you can turn neural network off and tune via the VE tables.

    Edit: Use the fuel mass delivery model from a Hellcat calibration for your injector model as a base since it's running hellcat injectors.
    I wondered if the stoich values were correct for E85 but I am not familiar with Dodge/Fiats values. I'll have to do some research there. I also didn't have a stock tune to compare. What I will do is have my Brother flash the stock tune and unmarry the Diablo and I will read it with HPt.

    Edit* I see that Dodge is Fuel/Air instead of AFR. So just divide 1 / .0688 = 14.7

    So for E80 I need to use 1 / .0986= 10.14

    Ill look up the Hellcat cat base.


    Thanks!!
    Last edited by 1scls1z; 4 Weeks Ago at 01:00 AM.

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    Quote Originally Posted by 1scls1z View Post
    I wondered if the stoich values were correct for E85 but I am not familiar with Dodge/Fiats values. I'll have to do some research there. I also didn't have a stock tune to compare. What I will do is have my Brother flash the stock tune and unmarry the Diablo and I will read it with HPt.

    Thanks!!
    Stoich values are just the inverse of AFR (or in other words, FAR - Fuel to Air Ratio).

    Stoich AFR for gasoline = 14.7:1
    Stoich AFR for e85 = 9.85:1

    1/14.7=.068 for gasoline
    1/9.85 = .1015 for e85

  5. #5
    I?ve heard people say the hellcat injectors don?t work well in the other engines. Also, copying the stock hellcat injector fuel mass tables directly over is not going to be dead on either based on the differences in the way fueling is handled between the two applications.

    I?d ditch those injectors for something you can get good data on.

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    Quote Originally Posted by spoolboy View Post
    I?ve heard people say the hellcat injectors don?t work well in the other engines. Also, copying the stock hellcat injector fuel mass tables directly over is not going to be dead on either based on the differences in the way fueling is handled between the two applications.

    I?d ditch those injectors for something you can get good data on.
    I wouldn't expect it to be dead on. I assume I can log afr error and multiply the error by percentage in the fuel mass ipw table to correct the fueling?

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    Quote Originally Posted by B00STJUNKY View Post
    Stoich values are just the inverse of AFR (or in other words, FAR - Fuel to Air Ratio).

    Stoich AFR for gasoline = 14.7:1
    Stoich AFR for e85 = 9.85:1

    1/14.7=.068 for gasoline
    1/9.85 = .1015 for e85
    Yep I get all that.

    So I spent half a day tuning yesterday. Setting the stoich values correctly made the car run much better. Fuel trims went rich... to be expected but it runs fine.

    Comparing injector data to a stock HellCat, what ever previous tuner did is not even comparable. In the IPW vs Fuel Mass table, The vertical scale is the same as stock with different data of course. Hell Cats are scaled differently. So I am not sure if I can use that data? Or would I use the HC scaling and Injector off sets?

    That being said, since the car fired right up, idled nice, took throttle input without dying, I put the ECU in VE mode to try tuning with the current injector data. Had to pull fuel at idle and down low then add fuel mid-upper range. Just blended into the upper and set the high end around 100 as a base until we hook the wide band up.

    So far much better.

    Question... Ideally (at least on GM)you want to tune VE off of STFT, but I can't figure out how to disable the LTFT on Mopar? I seen one guy logs both together in the Histogram. Either way I haven't found a direct answer. I have been using STFT data to populate my VE table, but I feel like I might be chasing my tail some with the LTFT on.

    Thanks

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    Last edited by spoolboy; 3 Weeks Ago at 10:34 AM.

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    Quote Originally Posted by spoolboy View Post
    Yep but I missed the part where he replied back saying that data worked. My brain is in information overload...thanks for the tip!!


    One issue I am running into is there are 15 vertical cells for the IPW vs Fuel Mass for the HC stuff and only 14 for the SP.
    Last edited by 1scls1z; 3 Weeks Ago at 04:55 PM.

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    Quote Originally Posted by 1scls1z View Post
    Yep but I missed the part where he replied back saying that data worked. My brain is in information overload...thanks for the tip!!


    One issue I am running into is there are 15 vertical cells for the IPW vs Fuel Mass for the HC stuff and only 14 for the SP.
    If you log, I beleive you will find that most of the cells aren't hit anyway.

    Also, keep in mind that the Scats do not have a factory wideband. If the car doesn't have and aftermarket WB installed, all you can work on is correcting fueling when the commanded eq is stoich.
    Last edited by spoolboy; 3 Weeks Ago at 08:27 AM.

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    Quote Originally Posted by spoolboy View Post
    If you log, I beleive you will find that most of the cells aren't hit anyway.

    Also, keep in mind that the Scats do not have a factory wideband. If the car doesn't have and aftermarket WB installed, all you can work on is correcting fueling when the commanded eq is stoich.
    Yep. I ended up going back to NN and logging Fuel trim + Fuel mass to correct idle and part throttle fueling. Just had to dial in the IPW's and fix timing. The car runs great now... I am leaving the PE multipler to command 11.99 afr until I can put a wideband on it and lean it out some.

    Thanks for the help.

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    Quote Originally Posted by 1scls1z View Post
    Yep. I ended up going back to NN and logging Fuel trim + Fuel mass to correct idle and part throttle fueling. Just had to dial in the IPW's and fix timing. The car runs great now... I am leaving the PE multipler to command 11.99 afr until I can put a wideband on it and lean it out some.

    Thanks for the help.
    Just out of curiosity, what do you have your fuel PE values set to?

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    Were the Hellcat tables fairly close to what you ended up with?

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    Quote Originally Posted by B00STJUNKY View Post
    Just out of curiosity, what do you have your fuel PE values set to?
    I used stoich value of .0986 for E80. WOT PE is set .0154 for 4800rpm on up. .0986 + .0154 = .114. 1/.114 = 8.77 commanded AFR on E80

    I said 11.99 afr because that is what the PE value equates to on a gas scale.

    Quote Originally Posted by spoolboy View Post
    Were the Hellcat tables fairly close to what you ended up with?
    The injector data the previous tuner used worked better. The main issue with the tune was that the timing was not right and the stoich table was not set properly for E. All I needed to do was fix the timing and scale the IPW's properly, then everything lined up. The timing was swinging negative on tip in causing the stumble. Part throttle and base needed work. I also removed all of the negative values and matched everything close on the low end. Used 10 degrees as a base. Now it never drops below 10 degrees at warm idle and when you blip the throttle.
    Last edited by 1scls1z; 3 Weeks Ago at 11:26 AM.

  15. #15
    Quote Originally Posted by 1scls1z View Post
    I used stoich value of .0986 for E80. WOT PE is set .0154 for 4800rpm on up. .0986 + .0154 = .114. 1/.114 = 8.77 commanded AFR on E80

    I said 11.99 afr because that is what the PE value equates to on a gas scale.



    The injector data the previous tuner used worked better. The main issue with the tune was that the timing was not right and the stoich table was not set properly for E. All I needed to do was fix the timing and scale the IPW's properly, then everything lined up. The timing was swinging negative on tip in causing the stumble. Part throttle and base needed work. I also removed all of the negative values and matched everything close on the low end. Used 10 degrees as a base. Now it never drops below 10 degrees at warm idle and when you blip the throttle.
    Would you share the data you wound up with for the PWs vs Fuel mass using Cat injectors on E85? This is a fairly common idea people bring up.

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    Quote Originally Posted by 1scls1z View Post
    I used stoich value of .0986 for E80. WOT PE is set .0154 for 4800rpm on up. .0986 + .0154 = .114. 1/.114 = 8.77 commanded AFR on E80

    I said 11.99 afr because that is what the PE value equates to on a gas scale.



    The injector data the previous tuner used worked better. The main issue with the tune was that the timing was not right and the stoich table was not set properly for E. All I needed to do was fix the timing and scale the IPW's properly, then everything lined up. The timing was swinging negative on tip in causing the stumble. Part throttle and base needed work. I also removed all of the negative values and matched everything close on the low end. Used 10 degrees as a base. Now it never drops below 10 degrees at warm idle and when you blip the throttle.
    So, just some thoughts on this from my perspective.

    Theoretically, you would ideally run the same Lambda value regardless of fuel type (Gasoline, Alcohol, etc...). Our Gen3 Hemis tend to like to run richer than other platforms, usually in the low 12's for N/A, and at least in the mid-to-low 11's for forced induction setups.

    Your setup appears to be N/A, so let's say an Ethanol-free Gasoline AFR target of 12.2. 12.2/14.7 = .8299 Lambda. Obviously the FA stoich value for Ethanol-free gasoline is .0680, and a PE Enrichment of .0139 to achieve your target of 12.2.

    Now, for e80, your stoich AFR is 10.14, or FA of .0986, as you said. The lambda value of .8299 multiplied by the stoich AFR gives you your desired PE AFR, so: 10.14*.8299 = 8.42. Then, of course the inverse of that would be your FA value: 1/8.42 = .1188. Now, subtract total FA from stoich to see what your PE FA adder values should be: .1188-.0986 = .0202

    So, .0202 is what I would personally use as a PE Adder for an N/A setup, assuming I wanted to run an equivalent Lambda for Ethanol based fuels as I would run for Gasoline based fuels.

    With the stoich plus the PE FA values you're currently running, and using Lambda or Equivalency Ratios to compare to Gasoline AFRs, your current Lambda/EQ Ratio would be akin to targeting about 12.72 AFR in the gasoline scale. It's a little bit leaner than I suspect you might want to be. Not on the verge of hurting anything per se, just leaner than Hemi's usually run. But perhaps that was on purpose, so take all this with a grain of salt.

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    Quote Originally Posted by B00STJUNKY View Post
    So, just some thoughts on this from my perspective.

    Theoretically, you would ideally run the same Lambda value regardless of fuel type (Gasoline, Alcohol, etc...). Our Gen3 Hemis tend to like to run richer than other platforms, usually in the low 12's for N/A, and at least in the mid-to-low 11's for forced induction setups.

    Your setup appears to be N/A, so let's say an Ethanol-free Gasoline AFR target of 12.2. 12.2/14.7 = .8299 Lambda. Obviously the FA stoich value for Ethanol-free gasoline is .0680, and a PE Enrichment of .0139 to achieve your target of 12.2.

    Now, for e80, your stoich AFR is 10.14, or FA of .0986, as you said. The lambda value of .8299 multiplied by the stoich AFR gives you your desired PE AFR, so: 10.14*.8299 = 8.42. Then, of course the inverse of that would be your FA value: 1/8.42 = .1188. Now, subtract total FA from stoich to see what your PE FA adder values should be: .1188-.0986 = .0202

    So, .0202 is what I would personally use as a PE Adder for an N/A setup, assuming I wanted to run an equivalent Lambda for Ethanol based fuels as I would run for Gasoline based fuels.

    With the stoich plus the PE FA values you're currently running, and using Lambda or Equivalency Ratios to compare to Gasoline AFRs, your current Lambda/EQ Ratio would be akin to targeting about 12.72 AFR in the gasoline scale. It's a little bit leaner than I suspect you might want to be. Not on the verge of hurting anything per se, just leaner than Hemi's usually run. But perhaps that was on purpose, so take all this with a grain of salt.
    Yea that is a little leaner then I was targeting. I did read one guy claim his made the most power on E85 in the mid 12's. Either way it's not showing any spark knock with 22 degrees timing.

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    Quote Originally Posted by spoolboy View Post
    Would you share the data you wound up with for the PWs vs Fuel mass using Cat injectors on E85? This is a fairly common idea people bring up.
    SureIMG_20190827_200518.jpgIMG_20190827_200539.jpg