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Thread: E85 Conversion - 2016 Scatpack

  1. #1
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    E85 Conversion - 2016 Scatpack

    I just want to sanity check my approach here if anyone is willing to lend some input.

    I'm switching over to a straight E85 tune since this isn't a factory WB car like the Hellcats (so the flex fuel patch is NOT applied in this case). The car is a 2016 Charger Scatpack, so it's an A8 392. It has an intake and exhaust (with factory cats) along with an AEM wideband.

    Here's my approach:

    - Adjust FA Stoich values for E85
    I'm assuming a pure E85 blend here and no winter blends to account for since it's not running the flex fuel patch with any kind of ethanol content inference. Stock value looked ever so slightly rich to me (maybe to split the difference with E10?).

    - Adjust PE Aircharge and PRatio tables
    I worked out a spreadsheet to compute the target FA and lambda values based on the new stoich values plus the PE adder values. I then compared to lambda for E85. They were a bit leaner after the stoich point change so I've added roughly 30-35% to the PE tables as a starting point, which puts commanded lambda somewhere between .80 and .87 after the E85 switch depending on the cell. I figure I can adjust if need be, but that should be a close starting point.

    - Adjust WOT Spark
    Plan to tune on the dyno. But generally, I expect about a max of 3-4 degrees additional based on what I've read about these cars.


    I have a couple of questions now:
    • Open Loop/Base - Do I need to add fuel to the cold/warmup table to account for more difficult starts on E? I've seen others mention the Startup Inj PW table for startup. Which would be correct, or is it both?
    • Fuel Mass Multiplier - I've noticed the alcohol multiplier table here for flex fuel as well. Should this change to account for E85?
    • Injector PW - I've heard people talk about changing this, but wouldn't the adjusted stoich values negate the need to adjust here? I'm aware of the approach many take with ANN on to adjust Inj PW instead of VE tuning. But isn't that to account for airflow characteristics rather than fuel characteristics?
    • Have I missed anything else?



    And pardon me if any of these are obvious. I'm fairly new to this. The little bit I did know was GM based and probably out of date by now.

  2. #2
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    Change your stoich, change your PE tables to get a proper lambda, leave EVERYTHING else the same until you get it on the dyno.

    Startups should be relatively the same as long as your startups on regular 93 were ok. In colder months (sub 45 degrees) you will need to add some fuel to the lower coolant temps in the startup inj pw table (go small, 5 % changes can do a lot).

    Once on the dyno add timing but don't go too crazy, e85 has a tendency to never show preignition on your knock sensors even when it is, and you can easily lose a ring land with that 392.

  3. #3
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    Quote Originally Posted by 06300CSRT8 View Post
    Change your stoich, change your PE tables to get a proper lambda, leave EVERYTHING else the same until you get it on the dyno.

    Startups should be relatively the same as long as your startups on regular 93 were ok. In colder months (sub 45 degrees) you will need to add some fuel to the lower coolant temps in the startup inj pw table (go small, 5 % changes can do a lot).

    Once on the dyno add timing but don't go too crazy, e85 has a tendency to never show preignition on your knock sensors even when it is, and you can easily lose a ring land with that 392.
    Good to know on the startups and other tables. Definitely didn't plan on adding any timing until on the dyno, so we're good there. Appreciate the input!

  4. #4
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    Update, first tests after switching over to E85 logged today. Fueling seems close, but in PE it's running tad bit lean. I left the Alcohol Fuel Mass Multiplier at 1. When I tested setting it at a value that you'd expect for 85% alcohol, it ran way lean in PE. Moving in the opposite direction, it goes richer. Maybe I'm missing something here, but why do the flex fuel vehicles have these multipliers set as low as 0.930 for 85%? Wouldn't you expect more fuel mass for E85? My actual lambda in PE seems close to dead on target with the alc fuel mass multiplier set somewhere around 1.03. And if not this multiplier, what else could cause it to go so much leaner in PE?

  5. #5
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    What fuel are you using, real pump e85? Did you test your concentration?

  6. #6
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    I'm asking because I don't know. But if you change the stoich to E85, is the alc fuel mass multi doing anything? If it's not using "Flex fuel" will it even reference that table?

    Is the stock fuel pump/injectors big enough to support E85? Again I'm asking because I don't know.

    What is your injector duty cycle?

  7. #7
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    I'm on pump E85. I have it measured at 74% ethanol according to the Innovate ethanol gauge. I can adjust my stoich for that. Still doesn't explain why the fuel mass multiplier works in the opposite direction than I'd expect.

    Jay - The multiplier still works and is used. It's just a 1x1 table for 0% alcohol in a non ffv.

    I had trouble with my inj duty cycle logging. I think I have it figured out today, so I'll have to get some new logs. Stock pump and injectors should be fine for a mostly stock, NA 392. But it's definitely worth checking. I thought that too but brushed it aside because it should be fine.

  8. #8
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    can you post up your tune? I want to see your PE tables.

    Problem with the multiplier is it is used against other alcohol tables, which for the most part have zeros or are missing entirely unless you perform the FF patch, with the exception of your PE tables which are used no matter what alcohol % you have. So i think the multiplier is being used against a zero table somewhere. In the hellcats, tables are populated and so works as expected.

  9. #9
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    Quote Originally Posted by 06300CSRT8 View Post
    can you post up your tune? I want to see your PE tables.

    Problem with the multiplier is it is used against other alcohol tables, which for the most part have zeros or are missing entirely unless you perform the FF patch, with the exception of your PE tables which are used no matter what alcohol % you have. So i think the multiplier is being used against a zero table somewhere. In the hellcats, tables are populated and so works as expected.
    Here you go. This is the E85 version, not the one adjusted for 74%.

    I don't see where that multiplier would apply other than the base fuel mass values, but perhaps.
    Attached Files Attached Files

  10. #10
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    So I got my inj dc logging fixed tonight. I'm barely running out of injector up top. Looks like it'll need larger injectors after all.

  11. #11
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    In other news, I got my cold starts worked out nicely. ID 1050x injector set ordered today to solve the injector sizing.

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    Quote Originally Posted by PittPaz View Post
    I'm on pump E85. I have it measured at 74% ethanol according to the Innovate ethanol gauge. I can adjust my stoich for that. Still doesn't explain why the fuel mass multiplier works in the opposite direction than I'd expect.

    Jay - The multiplier still works and is used. It's just a 1x1 table for 0% alcohol in a non ffv.

    I had trouble with my inj duty cycle logging. I think I have it figured out today, so I'll have to get some new logs. Stock pump and injectors should be fine for a mostly stock, NA 392. But it's definitely worth checking. I thought that too but brushed it aside because it should be fine.
    It may be how HPT has it mapped. It is Chrysler though so there's no telling. FA stoich comes to mind, haha

  13. #13
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    ID 1050x injectors installed. Startup and idle are fine. Time for some driving logs to see if that helps with PE.

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    So the ID provided data is pretty close for idle and part throttle. WOT is a different story. Car goes really lean and bogs. I must have something wrong with the injector data, but haven't been able to find it yet.

  15. #15
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    Is your fuel system other wise stock? The first lean issue you reported and now the same for the new injectors seems to indicate pressure loss in the system. ID injector data is pretty damn close for me when using it.

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    Fuel system is otherwise stock. I don't think it's pressure loss. I'm not logging fuel pressure, but I do have a gauge and I've eyed it during WOT for that exact thought. Pressure stays solid.

    I was running just a bit lean on the stock injectors, but it was getting closer to commanded, especially after putting the flex mass multiplier back to 1. Yesterday was pretty bad with the IDs. I'm talking .92-.97 lambda in PE. I did adjust the fuel mass temp modifier table late last night as I had missed it. This morning it was a little better, but still some odd behavior. There is about a second delay after entering PE and commanding a richer EQ until the actual drops, though the inj pw jumps up immediately. Then it gets pretty close to commanded, but slowly leans out against the commanded through the pull. Inj pw climbs slowly, but not much.

  17. #17
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    This is all normal behavior with the NN still enabled. Injector data might be spot on but it doesn't matter, something else throughout the weighting of the NN is off and so you need to adjust your injector data, that's your only choice if you want commanded to match actual.

    The delay to reading the enrichment could be a legit delay, where is the AEM mounted? You can up the enrichment rate or trip PE earlier / zero out the WOT Pedal hyst to get rid of the lean spike.

    Just noticed your PE Aircharge and PRatio tables are completely different, was that intentional? I always make both the same.

  18. #18
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    That makes sense to me. I did some tuning of the inj pw values based on eq error and with some minor adjustments I've been able to get it a lot closer.

    ID's data jumps from 44.3 mg to 443 mg of fuel mass. I also had the last 4 rows of the Inj PW vs Fuel Mass table set to the 443 mg row values since my table is larger than the ID provided table. Since it looks like the fuel mass in PE falls between the 44.3 and 443 mg rows, I interpolated the axis values and added three rows of resolution between those ID provided values with interpolated pw values to start (they would've been treated linearly anyway). That gave me a little more resolution to play with when tuning the pw values. With that, I've been able to get the commanded pretty close.

    Now the delay is still there. I'll have to try a couple of your recommendations to see if I can get rid of the delay. It might be the O2 sensor placement, but I'm not sure. Before the ID injectors, actual EQ dropped pretty fast when entering PE.

    As far as the PE Aircharge and PRatio tables go, that's because they're based on the stock values. I created a spreadsheet that allows me to enter a new stoich point. From that new stoich point and the stock PE tables, it does the math to produce the PE adder values for the new stoich point to match the resulting commanded lambda to the stock commanded lambda. It's just a starting point until I get the injectors dialed in, but I figured following stock commanded lambda would be a safe starting point while switching over.
    Last edited by PittPaz; 04-26-2019 at 10:07 PM.