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Thread: boost bypass control??

  1. #21
    Quote Originally Posted by ELaw View Post
    Looking at your tune I just realized something else... I'm not sure whether it can cause limp mode but it's definitely messed up.

    Your ECM 29480 table "Supercharger volumetric airflow vs. sc pressure ratio vs. sc RPM" seems to have several problems. First with the pulley ratio you're running, the supercharger RPM will be 23,544 at an engine RPM of 7,200... higher of course if you spin the engine faster. But the supercharger RPM axis in your table stops at the stock value of 18,000... that's a big difference!

    Likewise, the highest pressure ratio in your table is 2.10 (same as stock, at least on my car) which corresponds to a boost of about 16 PSI (at sea level). As you indicated, you're running a lot more boost than that!

    So you might try making some tweaks to that table and see if it helps.
    i have tried tweaking that table up and down and never really saw it make any difference. i have changed the axis up to 25000 rpms and it didnt change the way the car acted. thats why i reached out on here hoping some one has found something i can not. i have tried adjusting just about everything in the tune and can not get car to hold more than 20-21psi. it will spike to 24ish psi but drop back down and settle around 20psi. with the bypass still open. car drives amazing and runs 7.40-7.51, in the 1/8 mile just about everypass. even here in 77-85*F weather. so the car pulls hard just hoping for more. lol

  2. #22
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    Heh... well so much for my bright ideas!

    You still haven't mentioned (or have I forgotten), do you have any fault codes? I wonder if those could provide a clue about what's going on.

  3. #23
    Quote Originally Posted by Hemithis01 View Post
    yes i understand that the map sensors go to roughly 22psi but many have run more than that on stock map sesnors. i do have 3 bar map sensors that im going to put in and recalibrate tune for. i just have not gotten around to it yet. not sure how it work as i can not find anyone who has tried it before on our cars. so ill give it a try and see how it goes.
    Quote Originally Posted by ELaw View Post
    Heh... well so much for my bright ideas!

    You still haven't mentioned (or have I forgotten), do you have any fault codes? I wonder if those could provide a clue about what's going on.

    While I certainly appreciate your input in the fact that people are talking about this platform means we should all learn more here in the future. And as far as fault codes only time I get fault codes is when the car does go in the limp and then it just tells me that the ECM processor lost communication

  4. #24
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    I think you and I may be talking different kinds of fault codes... I'm wondering if you've scanned the car with a VCDS (aka "VAG-com") and see if there are any fault codes stored in the engine control module. I don't think the HP software will show those, and most generic OBDII scanners won't either (there are specialized VAG ones that will, although many won't tell you what the codes mean).

  5. #25
    Quote Originally Posted by ELaw View Post
    I think you and I may be talking different kinds of fault codes... I'm wondering if you've scanned the car with a VCDS (aka "VAG-com") and see if there are any fault codes stored in the engine control module. I don't think the HP software will show those, and most generic OBDII scanners won't either (there are specialized VAG ones that will, although many won't tell you what the codes mean).
    I work for an audi dealership as a tech and have both vag com and odis(dealer software). I honestly have never scanned car with either of them right after it hits limp mode.

  6. #26
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    I'd definitely scan it! Of course being an Audi it probably has a bunch of stored codes anyway, but it's just possible one of them relates to this problem.

    I assume you're running stock injectors? With E85 and higher-than-stock boost, you must be running a much higher injector pulsewidth/duty than stock... I'm wondering if there's some sort of limit for that in the ECU that is getting exceeded.

    Also I'm wondering if you could be maxing out your MAF sensor? I can see that causing limp mode.

  7. #27
    Quote Originally Posted by ELaw View Post
    I'd definitely scan it! Of course being an Audi it probably has a bunch of stored codes anyway, but it's just possible one of them relates to this problem.

    I assume you're running stock injectors? With E85 and higher-than-stock boost, you must be running a much higher injector pulsewidth/duty than stock... I'm wondering if there's some sort of limit for that in the ECU that is getting exceeded.

    Also I'm wondering if you could be maxing out your MAF sensor? I can see that causing limp mode.
    Im guessing its maxing map sensors and causing limp. These cars dont have a maf sensor. I know there is a table in the tune but i dont think it actually does anything. Maybe it uses the map sensors to build a maf airflow curve. Ill try adjusting that maf table and see if it changes anything

  8. #28
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    Gah I'm a dope... I just had my car torn half apart and should have remembered there was no MAF sensor!

    MAP sensor "overload" is definitely a possibility, but I wouldn't discount injector pulsewidth either. Don't these engines use 2 injections per cycle at some times? If the pulsewidth became long enough that the 2 injections merged into one (or threatened to), I could see the ECU getting pissed off.

  9. #29
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    split injection stops around 4000rpm

    I'm on a similar trajectory as you. I'll be going dual pulley this summer. For now I'm focusing on learning the trans side.

    I came across a thread in the dodge section about them hitting a torque limit in the trans and not being able to push it harder even though physically it could handle it. One of the solutions was to rescale the torque maps in the ecu so that actual torque is greater than what the ecu thinks it is and what the ecu tells the trans.

    What if there is some torque limit parameter that hptuners hasn't defined that's limiting your boost. Your driver demand might be mapped to demand "750ft/lbs" but that parameter limits you to "600ft/lbs" and that's why the bypass valve is only closing enough to reach the 600ft/lbs.

  10. #30
    Quote Originally Posted by ed1380 View Post
    split injection stops around 4000rpm

    I'm on a similar trajectory as you. I'll be going dual pulley this summer. For now I'm focusing on learning the trans side.

    I came across a thread in the dodge section about them hitting a torque limit in the trans and not being able to push it harder even though physically it could handle it. One of the solutions was to rescale the torque maps in the ecu so that actual torque is greater than what the ecu thinks it is and what the ecu tells the trans.

    What if there is some torque limit parameter that hptuners hasn't defined that's limiting your boost. Your driver demand might be mapped to demand "750ft/lbs" but that parameter limits you to "600ft/lbs" and that's why the bypass valve is only closing enough to reach the 600ft/lbs.
    I have read something like that as well in the past.

  11. #31
    so to give a quick update... i have been working with tyler a lot on my tune. we reworked the supercharger airflow, aircharge to tq, and tq to aircharge tables. right now car is holding 20+psi for all of 3rd gear. car pulls hard! its been 95+ degrees F here in florida so i havent been able to do full pulls. i prefer 1/8 mile racing anyway. im going to do some hits tomorrow and see how car performs. here is a log of the newer revised file.
    new tune 13 part 2.hpl

  12. #32
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    Any updates on this? Looking to get HP tuners as an alternative for my DP, big TB, ported setup

  13. #33
    Yes its all about requested vs actual tq.

  14. #34
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    This is very helpful, as I'm about to start the process of doing my s4. would you mind sharing you channel list as I'm going to start logging this week . thanks !

  15. #35
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    Should invest in the "User Defined Parameters" function of HPTuners, you can use Damos and convert the proper maps to TunerPro's ".xdf" format and adjust from there if the maps aren't already available.

  16. #36
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    Quote Originally Posted by Hemithis01 View Post
    Yes its all about requested vs actual tq.
    Hey would you mind looking at my logs to give feed back? I'm unsure if my bypass is dumping boost as there are 2 bypass position and 1 desired . Here are 3 logs on the dyno back to back runs . Thanks any and all help !

  17. #37
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    Quote Originally Posted by ELaw View Post
    Gah I'm a dope... I just had my car torn half apart and should have remembered there was no MAF sensor!

    MAP sensor "overload" is definitely a possibility, but I wouldn't discount injector pulsewidth either. Don't these engines use 2 injections per cycle at some times? If the pulsewidth became long enough that the 2 injections merged into one (or threatened to), I could see the ECU getting pissed off.
    I'm pretty certain the the "stratified" mode is only used during lean combustion.

  18. #38
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    Any update to your tune?

  19. #39
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    I'll post this here, as I responded to the OPs private message without looking at the date Hopefully this will answer some questions about dual pulley torque setpoint levels but please do ask if there are any more specific questions:

    Good afternoon! I'll take a look at your post now. In the meantime, try setting the setpoint mass air flow tables to request 1389 mg/stk (the logical limit for this table) at 750nm. Also jump into your indicated engine torque table and make sure the max indicated torque line is 750nm and change the maximum axis value to 1389 as well to keep the ECU happy.

    From there you can go into your maximum allowed torque tables and set your maximum target to 750nm (this will request 1389 mg/stk from the setpoint mass air flow tables).

    There are a few limiters from there, namely maximum airflow (which should be maxxed) and maximum intake manifold pressure (which you can set to 2600 to test), and maximum pq of the supercharger, which I set to 4 across the board so that it won't interfere, as it's just a backup map for high elevations (there are many other limiters that will interfere if you happen to drive through the mountains). You will also need to address the maximum indicated engine torque to clear your 750nm request and then some. I've seen some "tuners" lower the indicated engine torque maps but this is a hack fix and will result in other issues that will need to be worked around, as well as sub-par results.

    Once you've got those set, log indicated torque, mass air flow, driver requested or maximum torque, rfp (bypass valve) position and throttle position (along with the other normal logging parameters). You'll see quickly if you're hitting your targets. There are a lot more requirements than just what I've outlined, but that will get you most of the way!


    EDIT: I know I only have 3 post on this forum, so here's a link to our software to back up where I'm coming from
    https://garageautosports.com/en-ca/c...t-supercharged
    Last edited by GarageBill; 04-03-2023 at 04:40 PM.

  20. #40
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    Quote Originally Posted by GarageBill View Post
    I'll post this here, as I responded to the OPs private message without looking at the date Hopefully this will answer some questions about dual pulley torque setpoint levels but please do ask if there are any more specific questions:

    Good afternoon! I'll take a look at your post now. In the meantime, try setting the setpoint mass air flow tables to request 1389 mg/stk (the logical limit for this table) at 750nm. Also jump into your indicated engine torque table and make sure the max indicated torque line is 750nm and change the maximum axis value to 1389 as well to keep the ECU happy.

    From there you can go into your maximum allowed torque tables and set your maximum target to 750nm (this will request 1389 mg/stk from the setpoint mass air flow tables).

    There are a few limiters from there, namely maximum airflow (which should be maxxed) and maximum intake manifold pressure (which you can set to 2600 to test), and maximum pq of the supercharger, which I set to 4 across the board so that it won't interfere, as it's just a backup map for high elevations (there are many other limiters that will interfere if you happen to drive through the mountains). You will also need to address the maximum indicated engine torque to clear your 750nm request and then some. I've seen some "tuners" lower the indicated engine torque maps but this is a hack fix and will result in other issues that will need to be worked around, as well as sub-par results.

    Once you've got those set, log indicated torque, mass air flow, driver requested or maximum torque, rfp (bypass valve) position and throttle position (along with the other normal logging parameters). You'll see quickly if you're hitting your targets. There are a lot more requirements than just what I've outlined, but that will get you most of the way!


    EDIT: I know I only have 3 post on this forum, so here's a link to our software to back up where I'm coming from
    https://garageautosports.com/en-ca/c...t-supercharged
    GarageBill you've got no idea how helpful this is, great work