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Thread: Focus ST Torque Limits

  1. #1
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    Focus ST Torque Limits

    Hey guys, I'm having issues determining the torque limiters on my Focus ST. I have removed and adjusted all I could find, but I keep seeing a no limit- combustion stability- insufficient fuel limit with major throttle and power reduction. I have read through the ecoboost guide that a fellow tuner developed and he experienced the same thing, but on a different car and different tables. Any help would be greatly appreciated.

    Kris
    Last edited by kris5597; 05-04-2017 at 08:45 AM.

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    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by kris5597 View Post
    Hey guys, I'm having issues determining the torque limiters on my Focus ST. I have removed and adjusted all I could find, but I keep seeing a no limit- combustion stability- insufficient fuel limit with major throttle and power reduction. I have read through the ecoboost guide that a fellow tuner developed and he experienced the same thing, but on a different car and different tables. Any help would be greatly appreciated.

    Kris
    Please post the tune file, and the log.
    Eric Brooks
    HP Tuners, LLC

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    This is my latest revision for tune and log. I appreciate the help.
    Attached Files Attached Files

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    Looks like your hitting the Combustion Stability Limit Max MAP under Torque Management > General. This is what is causing your throttle to be pulled early in the run. As far as Insufficient Fuel Flow, I haven't seen a way to get past that personally but it doesn't seem like your rail pressure drops. One way would be to try and command a bit leaner WOT Lambda. These DI/Ecoboost engines tend to enjoy running a tad leaner anyway. I would be careful with the way you have your tables setup and be very wary of LSPI. It looks like you have many of the limits moved out of the way at low RPM so if you were to get a good spike of boost down low and experience LSPI, it could be catastrophic. Looks like you have a larger turbo than stock?
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    The car is completely stock. I can't raise the combustion stability max map anymore to remove it, it's maxed out. After I determine what is limiting throttle I will work on dialing it in. Do I need to adjust the waste gate setting to regulate boost so the throttle will stop trying to regulate?

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    Tuner Blown383's Avatar
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    You sure have made many changes that do not need to be made on a stock car. I would put all your torque tables and driver demand tables back to stock. Then slowly add to the driver demand table to achieve the boost you want. If the engine and turbo are stock then the torque tables are pretty accurate. Keep in mind the "Knock Retard" PID does not work on these cars. You will need to log "Knock Cyl 1" through Cyl 4 for proper knock monitoring. Like I said before, please be very wary of LSPI as the stock turbo spools extremely fast and doing pulls from a low RPM at high load/high gear can cause it. You should be able to go over the Comb. Stab. Max Map limit. The ECU will have no problem accepting a larger value if you override the value limit.
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    Thank you very much for the tip, the tables were adjusted trying to track down the limiters. I will start from scratch and work my way back down the right path. I was not aware I could override the value limit and it accept it, thank you.

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    Senior Tuner metroplex's Avatar
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    I've never touched the torque/inverse torque tables nor did I recommend them in my guide, but the first things people seem to do is modify those tables. The best it can do is try to trick the ECU and cause a very high TIP pressure but nothing gets to the manifold, causing cool blow off valve sounds at least on my SHO. Worst case scenario is it sets off the wrench icon and you get to limp home at a very low speed.

    I didn't need to touch the wastegate settings either. The ECU does it automatically.

    You should reduce the fuel enrichment pedal setting to 40% or so. This value doesn't reflect the physical position of the throttle from what I saw, but more like what throttle plate angle it sees when you are physically WOT.

    I've seen the Insufficient Fuel Flow error on 2015-up vehicles where the fuel rail pressure is still 2100+ psi with no signs of drop. On my SHO, I kept the Comb Stability Max MAP to 31.93 psi and routinely hit over 17 psi without running into a limiter. It's *possible* that because the 2.0/2.3 EcoBoost runs much higher boost (22+ psi) that this value might be too low, but still when I ran it up to 19+ psi I never had an error.

    Another thing to try is lean out the WOT lambda. The GTDI engines can run a bit higher lambda, like at 0.85 (which is like 12:1 using 14.08 stoich for E10)

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    I've returned back to stock torque/ inverse torque tables. I have also gone over the max map combustion stability by overriding the table. Stock boost setting is 22psi, I will maintain it around this area, however to do so, I will need to up the combustion stability map max. From what I have seen and been told, agreeing with you, DI usually has no problem running leaner, around .85-.86 lambda, but if there is no harm in running richer, I'd feel more comfortable doing so to help compensate the napalm that will be coming out of the turbo by the higher rpms. @Blown383 has given me some pointers and I believe we have determined what my issue is, I will check when I get off my day job and do some more testing, tonight is tuning night and I plan to finish it up. I appreciate all the help guys, I will keep the thread updates with my results.

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    Quote Originally Posted by kris5597 View Post
    Hey guys, I'm having issues determining the torque limiters on my Focus ST. I have removed and adjusted all I could find, but I keep seeing a no limit- combustion stability- insufficient fuel limit with major throttle and power reduction. I have read through the ecoboost guide that a fellow tuner developed and he experienced the same thing, but on a different car and different tables. Any help would be greatly appreciated.

    Kris
    Here’s my 2-cents. First, I’m no expert and am struggling to eliminate the Comb Stab and Popcorn limits myself, but I have successfully got past the Insufficient Fuel Limit for now anyway.

    First you might try to increase your Injector Duty Cycle Limit and Max DC vs ECT table values from .95 up closer to 1.

    If you still have Insufficient Fuel Limits after this, you might slowly open up the Injector Timing Window (i.e. SOI – EOI). When doing this go slow and monitor your fuel rail pressure to be sure it doesn’t drop significantly. If the rail pressure drops you don’t have sufficient fuel pump output to support more power.

    Now how much you can change the SOI and EOI - I don’t know. The SOI Minimum scaler seems to be in crank degrees, so convert it to degrees BTDC (e.g. 720 – 383 = 337). So 337 degrees BTDC is the earliest Start of Injection possible. I wouldn’t stray too far from this number. Now you can change the Single Injection Intake Timing table based on the SOI Minimum BTDC. Now adjust the End of Injection a bit in the EOI vs Pressure table. I don’t know how far you can go (i.e. to rising cylinder pressure and ignition timing) – go slow. As your maximum injection window increases (SOI – EOI), be sure to increase your Max Inj Angle Limit scaler to coincide.

    I increased my injection window by 15 degrees in the areas I had Insufficient Fuel Limits and it has eliminated the issue with no ill effects.

    Keep us posted as to how it goes and if you figure out how to get past the Comb. Stab. Limit.

  11. #11
    CSL isn't your problem and isn't actually limiting you. In order to enter CSL limiting, you must have ALL conditions met, Manifold > Calibratable, Torque > Calibrated, TQ Ratio < CSL Tq Ratio.
    CSL isn't something people should have to routinely mess with, its only designed to be active when spark is sufficiently retarded to keep combustion stable. Your Torque Source would say CSL, not your Driver Demand Source.
    In this case, your change of CSL Tq Ratio is actually backwards and is more aggressive than stock. Lower numbers are less aggressive.

    Driver Demand Source being CSL = Load limited by LSPI or Effectiveness tables.
    For example, my car has CSL limits completely stock, and I'm near 500whp on a Focus ST.

    As well, you appear to have neutered octane adjustment, LSPI protections, part pedal load limits (these are the max load you can see at stoich. Yours would allow almost 2.7 (there's a hidden OAR multiplier to them). I doubt you want that).

    I guess what I'm trying to say is your current load limit is actually the LSPI limits you have. What you're missing is your Desired TIP Max Pressure. That is still stock at 75in.Hg. You can command all the torque or load you want, but the system will not be able to reach it because your TIP Desired is capped at 75in.Hg. This is under Torque Management > Turbocharger > Desired TIP. As well, your Compressor Speed Limit will be limiting you as well. Torque Management > Turbocharger > Pressure Ratio.

    Those two combined are what is actually limiting you. I'd bet if you logged Desired Load you'd see its higher than your actual and you're being limited elsewhere.


    As for insufficient fuel flow, this is a backwards calculation. Under Fuel > Injector Control > Limits, you have a max injection angle, and duty cycles. How the ECU works at a basic level is its using the start of injection as a constant, and will increase the window it injects for based on how much fuel you need. It does hit a Maximum window (240* stock) over which it will not inject longer. This window can be further limited by the "duty cycles" (95% stock form). The ECU takes this maximum window * max DC and converts it into a fuel flow, and then from there with your desired AFR back into an airflow, which becomes the Insufficient Fuel Flow limit you see. You either need to expand your maximum window or the DC to allow longer injection. As long as you're not losing fuel rail pressure, you're good to go (and a certain amount of drop in FRP can happen and still have solid AFR/injection windows). I'd recommend raising the Max Injection Angle here to increase this limit. As well, you may have to mess with the other window clips (EOI vs Pressure clips the endpoint to prevent injecting into the combustion cycle. This can be moved quite a bit and is in *BTDC, just like spark advance).

    As well, this engine doesn't lose much power from running rich, but does get a decent knock margin from it, so you'll notice alot of the big name tuners for it will run Lambda around 0.78 - 0.82 at the leanest.
    Last edited by Bugasu; 12-01-2016 at 02:56 PM.

  12. #12
    Senior Tuner metroplex's Avatar
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    Bugasu: I use that Desired TIP Max Pressure to limit TIP pressure on my SHO, so the Desired TIP pretty much never goes above this value. Manifold pressure is just slightly lower than TIP pressure.

    It's true the 2.0L/2.3L GTDI would run much higher airload numbers than the 3.5L EcoBoost. I know my 2.0L LNF GTDI in the Cobalt routinely sees over 220% airload.

    When I ran 0.79 to 0.8 lambda, I'd run into insufficient fuel flow errors on the SHO - the fuel pressure would drop a bit as well. I eventually kept it at 0.85 and the fuel pressure remained steady. I didn't notice any extra knock protection with 0.79 or 0.82 lambda vs 0.85

    On the LNF, many big name tuners would use 0.85-0.87 for max power. The factory setting went as high as 0.95 for the lower RPMs at WOT. I understand it is a different engine, but is a GTDI 2.0L inline 4 with a Bosch fueling system and a mechanical HPFP.
    Last edited by metroplex; 12-01-2016 at 03:23 PM.

  13. #13
    Quote Originally Posted by metroplex View Post
    Bugasu: I use that Desired TIP Max Pressure to limit TIP pressure on my SHO, so the Desired TIP pretty much never goes above this value. Manifold pressure is just slightly lower than TIP pressure.

    It's true the 2.0L/2.3L GTDI would run much higher airload numbers than the 3.5L EcoBoost. I know my 2.0L LNF GTDI in the Cobalt routinely sees over 220% airload.

    When I ran 0.79 to 0.8 lambda, I'd run into insufficient fuel flow errors on the SHO - the fuel pressure would drop a bit as well. I eventually kept it at 0.85 and the fuel pressure remained steady. I didn't notice any extra knock protection with 0.79 or 0.82 lambda vs 0.85

    On the LNF, many big name tuners would use 0.85-0.87 for max power. The factory setting went as high as 0.95 for the lower RPMs at WOT. I understand it is a different engine, but is a GTDI 2.0L inline 4 with a Bosch fueling system and a mechanical HPFP.
    Exactly, thats what its for. That's what is currently limiting him. If he logged Desired Load, I'd bet that its still quite high, above his current load, but he cant reach that load because of that TIP Limit.

    Air Load is just a function of cylinder aircharge over ideal aircharge at 100% VE. A smaller engine will need higher load to hit the same torque, so comparing it to the 3.5, it'll be much higher for more torque

    This vehicle won't drop fuel pressure as quick as the 3.5L either. The window can be increased significantly. As to the knock protection, you may not have noticed because Lambda Spark by default increases borderline timing (I.e. the knock borderline is infact moving). 0.82 vs 0.75 is nearly 3.5* of change on the FoST.

    This is not an LNF in the slightest. LNFs do much better lean. FoSTs burn out pistons at the same Lambda. Stock it targets 0.82, but above 4.5k you almost always get Cat Temp cooling which will drop you to 0.68. Regardless, the change in torque from 0.7 to 0.85 is ~3.8% via factory calibration on the FoST. Lot of heat for little gain that can be made up in other places. As someone who's tuned a boat load of them, I would not run them at 0.85. I don't know of any big names in FoST tuning that do.

    Lower RPM WOT can be much higher, because its much lower load or during blowthrough. Different animal on the FoST. But by the time its spooled, nearly every big name is <=0.82.

  14. #14
    Senior Tuner metroplex's Avatar
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    Ah, that makes sense.
    But for Lambda spark, it looks like it pulls timing with lower (richer) lambda. I do log the borderline and MBT spark as well as the final spark.
    What would you recommend for WOT lambda on the SHO or EcoBoost 3.5 in general? The same 0.79/0.80 as stock?
    Last edited by metroplex; 12-01-2016 at 03:54 PM.

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    Quote Originally Posted by Bugasu View Post
    I guess what I'm trying to say is your current load limit is actually the LSPI limits you have. What you're missing is your Desired TIP Max Pressure. That is still stock at 75in.Hg. You can command all the torque or load you want, but the system will not be able to reach it because your TIP Desired is capped at 75in.Hg. This is under Torque Management > Turbocharger > Desired TIP. As well, your Compressor Speed Limit will be limiting you as well. Torque Management > Turbocharger > Pressure Ratio.
    If that is the case, then my Desired TIP Max Pressure should be 22.3psi if you remove atmospheric pressure. I am only seeing max of 20 psi and the car is still cutting throttle. How am I hitting that limit???

    Kris

  16. #16
    Quote Originally Posted by metroplex View Post
    Ah, that makes sense.
    But for Lambda spark, it looks like it pulls timing with lower (richer) lambda. I do log the borderline and MBT spark as well as the final spark.
    What would you recommend for WOT lambda on the SHO or EcoBoost 3.5 in general? The same 0.79/0.80 as stock?
    Lambda spark adds timing on the FoST. Positive = Add, Negative = Remove. Its a straight adder.
    As to what to do with a 3.5, I'm honestly not as familiar. I have tons of dyno time with the 2.0 and lots of playing with it. I don't have the equivalent experience with the 3.5 where I've had time to play with lambda on a dyno and see changes. They're different motors with different designs, so its tough to say. There is a lambda torque adjuster in the ECU that is used as part of the torque model that can indicate how the torque model is adjusting predicted torque, and for the FoST that was nearly dead on with what I saw on the dyno so I trust it. I don't know if you have access to see that table, but I feel like I've seen it before for some strategies.

    Quote Originally Posted by kris5597 View Post
    If that is the case, then my Desired TIP Max Pressure should be 22.3psi if you remove atmospheric pressure. I am only seeing max of 20 psi and the car is still cutting throttle. How am I hitting that limit???

    Kris
    Your Desired TIP appears to be hitting ~75in. Hg (your limit) in your log while you're DD Source is CSL/Popcorn, and doesn't drop until your insufficient fuel flow is active, which is why I say this. There should be a Desired Load loggable for you that lets you see if my assumption here is correct. If your Load Desired stays high but your actual load doesn't reach it, that would confirm it. Unfortunately, there's no source in the ECU stored for any of the limits to TIP Desired, so these can be harder to find. Thats why I mentioned Comp PR, as its another possibility. You already raised the turbo temp ones which is another one as well.

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    So if I am hitting TIP max, then what would I do to eliminate throttle closure torque limit? Increase TIP max? Wouldn't that allow for more boost?

    Also, boost/ power falls off really bad before I hit insufficient fuel flow, per my log. Would the insufficient fuel flow limit cause the ecu to cut boost/ power there? Even with the stock tune, the driver demand limit source reads exactly as my car is in the same spots during the pull as it is currently.

  18. #18
    Senior Tuner metroplex's Avatar
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    What table # is the Lambda Torque Adjuster table in the Focus ST? Where is it found?

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    52028 I believe.

  20. #20
    Senior Tuner metroplex's Avatar
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    That's all 0 on every tune file I could find, including the Focus RS