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Thread: 3.0t tuning question

  1. #1
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    3.0t tuning question

    Hello all!

    I've got a 2014 A6 with the 3.0t engine that I want to tune, and have a question.

    I downloaded a 2014 S4 file that someone uploaded here. That car uses the same engine as mine, but it has a higher HP rating and in particular a higher rev limit (7200 RPM vs. 6600 for the A6).

    I compared the two files and see some differences in some tables that probably would account for the engine making more torque at certain points, but I can't find any differences between the two files in the rev limit section! I understand that with an automatic transmission the engine may not reach the rev limit because the transmission would upshift, but even the manual-transmission tables and settings appear identical.

    Is there something I'm missing?

    I don't know if it's proper to repost a file someone else posted here, but I'll attach my stock tune.
    Attached Files Attached Files

  2. #2
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    yes the extra power is created from the s4 having a higher rev limit. there is one for both the ecu and the tcu. you can see and raise the limit in the ecu but you can not read the tcu of the s4 so therefor you can not raise it. the car will shift at which ever is the lower setting. the tcu is set for around 6900 in the s4 IIRC. i am tuning both my car and my buddies 2013 s4 right now. i have hit a limit with his car until he gets a tcu tune from someone. i can not wait until hptuners has the ability to tune the s4 trans. let me know if you have any further questions. i have my car running quite well so far and got it down to 3.9 seconds 0-60mph from 5.3 seconds stock.

  3. #3
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    Heh... I have nothing *but* questions!

    I've tuned a few cars before and am more or less an expert with Megasquirt, but that and the other older-car systems I'm familiar with are about 1/100 as complicated as this. Well "these" actually... I've got an A4 2.0t and the A6 and I'm trying to tune both. Interestingly even though they've got the same transmission, the tuning of the two trannies is very different... not just what the maps contain, but what maps exist and how they're structured. The tuning of the engines I expected to be different as they've got different engine-management systems.

    Anyhow, if you have any pointers on where to start or what to watch out for, it would be much appreciated!

    Comparing the S4 tune to my A6 tune, this is what shows up as different:
    Capture.PNG

    It's funny the DTC list shows as different... I've found it says that even if you compare a file to itself! Must be a bug.

  4. #4
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    i always start by datalogging stock tune. then changing fueling to what i want to run it at, adjust limiters(rpms and boost), adjust full load throttle %, adjust spercharger ratio. datalog again and see how it effected it. then i start adjusting torque request tables (airflow and driver demand). once i get the boost bypass to act how i want. i just fine tune those tables. then i move to spark and fine tune again after putting power(timing) is put into it. hope this helps

  5. #5
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    Hey... the engine "Max airflow vs. RPM" table, does anyone know the units on that?

    The label next to the number-entry box says "mg" but that seems incomplete... I'd expect it to be "mg/sec" or "mg/combustion" or something.

  6. #6
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    I've got a couple of other questions, if anyone happens to know...

    It seems like there's some kind of mechanism in this engine where if you stab the throttle a small amount but quickly, the engine reacts more aggressively. It's almost as if it's deciding to switch into "sport" mode by itself at times... but if you're more gentle on the throttle this does not happen. Under "torque management" - "driver demand" I can see the pedal-position-to-torque mapping tables for both regular and sport modes, but I haven't found anything that would control when it switches from one to the other - or decides to just become more responsive, whatever is going on. Does anyone know anything about this? Just to be clear, I'm talking about the behavior of the engine, not the transmission - I know the transmission (my car has the ZF 8-speed) has "aggression" programming I'm still trying to get my head around.

    My next question is even goofier. On the A6 (I don't think this is true of the S4?) the tach redline is indicated by a series of LEDs around the perimeter of the gauge. I've seen tuned cars where the redline indication was higher than stock, so I suspect that LED "display" is being controlled somehow by data from the ECM. Does anyone know how to change that output so if I raise the redline it'll be indicated correctly on the tach?
    Last edited by ELaw; 10-30-2019 at 07:05 AM.

  7. #7
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    30T-Torque-System.jpg30T-Airflow-Maps.jpg

    Allow me to break down the torque model as i understand it, Okay so first thing you're looking at is the pedal position, this is input by the driver and you'll find this value on the axis of both ECM 29330 and ECM 29328 as an input VS RPM with the Output being a percent value of the Maximum Allowed Torque (ECM 29542). if you look at the values of High/Low Speed Blend (ECM 29368) you will also notice that this is what dictates which map (29330 or 29328) the value gets pulled from based on how fast you are travelling.

    So now we take that torque value and it translates to an Aircharge value going through Torque to Aircharge (ECM 29523) and verifying torque monitoring through Aircharge to Torque (ECM 29540). Being directly limited by Max Airflow vs RPM (ECM 29520)

    This is a VERY rough walk through of where it starts and ends but there are many many other factors that come into play, this is just the basics to get you started on increasing airflow through your engine.

    Always log your vehicle to find where the first sane limiting factors are and change those to see what happens, then log more

    I believe what separates the sport maps and regular maps is just weather or not the driver has sport mode engaged via the shifter select in the car...

  8. #8
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    That's very helpful... thanks!

    I know it makes sense the engine would not automatically switch from normal to sport by itself, but I swear the throttle response changes sometimes depending on how fast you push the pedal down. I'm going to try to get a log of it and maybe it'll show whether or not I'm imagining things...

  9. #9
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    Look at how the torque table and airflow tables are mapped, if you press the pedal hard when you are lower in the RPM range you will hit higher requested airflow values... so it’s how the car is mapped from factory

  10. #10
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    I get that but it seems like (and I'll admit I could be wrong here) that *rate* is a factor too. Like from a stop if you push the pedal from 0 to 1/3 in 1 second you get a certain amount of power, but if you push the pedal from 0 to 1/3 in 1/2 second you get much more power.

    I wonder if what I'm perceiving is an effect of the automatic transmission? Like if you press the gas gently it quickly upshifts, but if you press it faster (but the same amount) it remains in lower gears for longer.

    I'm working on tuning the tranny in the car too, but with all those maps, figuring out which one is active when is going to make my head explode!

  11. #11
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    Any updates on tuning this platform?

  12. #12
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    No... I've been wicked busy lately and decided to try and focus my energy on tuning the A4 which appears to be the more complicated of the two.

    I'll get back to the A6 eventually but want to try and see what I can get done on the A4 while I've got some momentum. Plus of the two, the A4 is the one that more badly needs tuning because it's got so much less power!

  13. #13
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    Hey so here's an interesting one I found poking around the engine maps for the A6. Take a look at the gear numbers in this image:
    A6 AT max torque.PNG

    Notice they go from 0 to 9. What's that about? Is this a zero-based table where 0 = first gear? Or does 1 = first gear and zero has some special meaning?

    I can understand the gear numbering going up to 9 in case they ever want to fit a tranny with more gears, but that zero has me confused.

  14. #14
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    maybe neutral and reverse for that specific map

  15. #15
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    That makes sense!

    I'm hoping I can find the time to experiment with this a little this afternoon. I'm going to try making a dramatic change (like divide by two) to one row at a time and see what effect it has.

  16. #16
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    So I've turned my attention back to this car and spent some time this afternoon tuning since I thought I had an idea of how everything fits together. I flashed my new Miracle Tune to the car and it seems to have done... pretty much nothing! Do you have any insights on what I'm doing wrong?

    The attached file that has "attempt 1" in the name is my stock file with a few things from an S4 file I found here merged in. The attachment "A6 9 min..." is a log using that tune.

    The other two ("engine tune 2.0" and "engine 2.0 pulls") are my new tune from today. If you look at the WOT areas in that log vs. the other, you'll see there's very little difference... and the car's performance doesn't feel significantly different.

    I read your post above about the torque model and I don't see anything wrong with my file there... the torque I'm requesting seems to fall within the range of the OE torque model tables.

    Is it possible the "big guys" (I'm looking at you, APR) are getting their increases more with timing than with boost increases? I didn't change timing at all.

  17. #17
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    Okay, lets get back to basics here, you need to log your car in completely stock form, full 3rd,4th,5th pull if possible post that.

    then post only one tuned file as working with too many different revisions will just get confusing and cause more headaches than its worth, compare logs side by side to see what the next limiting factor is...

    also for a more accurate understanding of whats going on you should add these variables. Requested torque, Requested Map, Timing Retard, Short Term Fuel Trim, Cylinder airmass.

    for a start i found a few maps you'll need to change for your car to request more boost/Torque and request less By-pass valve angle

    [ECM] 29572 - Maximum Torque Limit at Full Load
    [ECM] 29520 - Max Airflow vs. RPM
    [ECM] 29522 - Bypass Mass Airflow Correction vs. IAT
    [TCM] 30605 - Maximum Available Engine Torque 0
    [TCM] 46856 - Gear Max Torque Limit Normal

    once you have had a look at these maps and found the limits try raising them and logging then post up your file and the log associated with it

    hope this helps

  18. #18
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    Well... now I seem to have a different problem. I need to increase the MAF "max" on my Scanner gauges and graph because I'm exceeding it! In other words, I think I've succeeded in adding some fastitude to the car.

    I fooled with most of the tables you suggested... I'm still trying to get my head around the bypass airflow correction. [ECM] 29572 is a tricky one because it only appears in advanced view! But my MAP and MAF numbers are considerably higher and the car definitely pulls harder. At WOT the supercharger bypass valve is completely closed below about 3350 RPM so it looks like the blower isn't able to provide as much boost as is being requested. Hopefully that'll change when I install the pulley I ordered a few days ago.

    It also seems like I could raise the shift points a little more, but I'm a little concerned the RPM is being sampled at such a low rate I'm not seeing the absolute maximum number. I think I might do more testing with fewer logged parameters and see if I can hone in on that a little more closely.

    Latest tune and log are attached for anyone interested.
    Attached Files Attached Files
    Last edited by ELaw; 1 Week Ago at 09:04 PM.

  19. #19
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    As part of my process, I wrote up a file that outlines my understanding of the torque-management process... kind of a flowchart with no graphics. Maybe it'll help others who are trying to learn this, and I'd welcome any input from the 99% of folks out there who are more knowledgeable than I am!

    Code:
    1. Driver presses gas pedal down a certain amount.
    
    2. Gas pedal position & engine speed are used to look into "Percent torque request" table.
    	Tables for AT are [ECM] 29328/29329/29371 ("Low"/"Low Sport"/"Offroad"), 29330/29331/29372 ("High"/"High Sport"/"High Offroad")
    	Blend betwen "low" and "high" comes from speed/gear tables 29368/29369 ("Blend"/"Offroad Blend")
    	Regardless of which table or blend, WOT should always yield a value of 100%
    
    2a. Monitoring tables (for AT) 29332/29333/29334/29373 ("Base"/"Sport"/"Sport 2"/"Offroad") check the % from step 2.
    
    3. Percent from step 2 & gear are fed into (AT) tables 29542/29556 ("Max Torque 0"/"Max Torque 1")
    	Output is requested torque
    
    3a. Requested torque is monitored(?)/capped(?) by 29613 ("Max Torque at Clutch")
    
    3b. IMPORTANT? Visible in advanced view only is 29572 "Max Torque Limit at Full Load"
    
    3c. Torque can also be limited by transmission?
    
    4. Requested torque from step 3 & RPM are fed into 29523 ("Indicated Torque to Aircharge")
    	Output is an aircharge value
    
    4a. 29540 ("Indicated Aircharge to Torque") uses airflow and RPM to compute torque
    	Not sure what this is used for?
    
    4b. 29520 ("Max Airflow vs. RPM") caps airflow based on RPM?
    
    What I don't know is what the ECM dows with the aircharge number from step 4?
    	29480 "Supercharger Volumetric Airflow vs. SC RPM" seems to relate supercharger RPM (presumably calculated from crank RPM) and pressure ratio to airflow.
    	But the numbers don't make sense... airflow increases with RPM as expected, but decreases with pressure ratio?
    	Maybe that table shows airflow per revolution of the supercharger (so need to multiply by RPM to get actual airflow)?
    
    29524 ("MAP Limit") and 29481 ("PR Limit") can limit manifold pressure.