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Title: negative deviation on part throttle Post by: aef on March 04, 2019, 03:20:40 AM hi,
is this a boost pid problem or a wg preload too strong or a dump valve spring too strong problem? as you can see on steady pedal boost will rise and throttle cut will happen. maybe its related to KFVPDKSD/KFVPDKSE but i have to read alot about it first ::) Title: Re: negative deviation on part throttle Post by: nyet on March 04, 2019, 11:31:12 AM Your LDRXN is probably too optimistic.
Title: Re: negative deviation on part throttle Post by: fknbrkn on March 04, 2019, 11:54:03 AM Yep its typical result of non fixed KFVPDKSD/KFVPDKSE axis
Title: Re: negative deviation on part throttle Post by: aef on March 25, 2019, 02:31:32 AM I tried to fix it but without success. Wiki tells the following:
Quote The axes of these maps are nmot (engine speed) and vpssplg_w (requested pressure ratio) and the Z-values are pressure ratio across the throttle body. Look for the values in the table that start to exceed the threshold of PSPVDKUG (generally 0.95) and approach 1.0, and trace up to the vpssplg_w axis. The pressure ratio minus 1 bar at this column (when stock) should be your wastegate pressure (3-6psi for stock wastegates). An easy way to make an initial pass is by only modifying the vpssplg_w axis data. Take the ratio of the new pressure to the stock wastegate pressure (e.g. 1.8/1.3 = 1.38), and correct the vpssplg_w axis by multiplying each value by this ratio. This roughly sets base boost for proper throttle control. You can further tune this table by making sure areas below the spring/cracking pressure of the wastegates stays below the value in PSPVDKUG. I did multiply by two or little over two to cover the highest vpssplg_w i am seeing. ??? The result is throttle is not 100degree open while going wot. So my axis data is wrong and boost will be regulated by throttle (not duty) not only in part/light load. :( Can someone describe in own words how to modify the axis or whole table? attached is KFVPDKSD with wrong modified x-axis, the log after and my initial pass with zero duty and new 0,9bar wg Title: Re: negative deviation on part throttle Post by: aef on March 26, 2019, 04:51:33 PM ???
attached is another log with boost at light load where n75 is inactive so i have to tell the trottle to regulate boost. Quote The pressure ratio minus 1 bar at this column (when stock) should be your wastegate pressure (3-6psi for stock wastegates). i dont get it can someone explain it in own words pls attached is a log with a spike at 14seconds KFVPDKSD/KFVPDKSE stock Title: Re: negative deviation on part throttle Post by: phila_dot on March 27, 2019, 12:32:59 PM Sorry, but you're going in the wrong direction with this.
VPDK only regulates the pressure pre and post throttle. Below cracking pressure (0.95)- normal throttle behavior Above cracking pressure (>0.95) - throttle is forced open 95-100% Your issue isn't rooted in either of these scenarios. You need one or more of the following: more appropriate load request, throttle tuning, boost diagnosis adjustments. The pressure axis is a ratio of desired manifold pressure : ambient pressure. vpsspls_w is a desired pressure ratio pre-throttle pressure : manifold pressure. vpsspls_w is used to convert desired manifold pressure pssol_w to desired boost pressure plsol_w. It is also used to regulate pressure pre and post throttle via the throttle plate. If vpsspls_w is > 0.95, then the throttle plate is forced to open that percentage towards WOT. Anytime vpsspls_w is 1, then the throttle is forced to open 100%. It has no other function and no direct influence on the boost PID controller. Title: Re: negative deviation on part throttle Post by: aef on March 28, 2019, 12:47:48 AM Hmm now i am even more confused.
Currently its running with doubled x axis values in KFVPDKSD/KFVPDKSE because wg cracking pressure before and after is 0,45bar and 0,9bar. The wiki sais Quote An easy way to make an initial pass is by only modifying the vpssplg_w axis data. Take the ratio of the new pressure to the stock wastegate pressure (e.g. 1.8/1.3 = 1.38), and correct the vpssplg_w axis by multiplying each value by this ratio. This roughly sets base boost for proper throttle control. You can further tune this table by making sure areas below the spring/cracking pressure of the wastegates stays below the value in PSPVDKUG. I found several posts while reading more about KFVPDK* for example: http://nefariousmotorsports.com/forum/index.php?topic=13867.msg112544#msg112544 or: http://nefariousmotorsports.com/forum/index.php?topic=9221.msg95068#msg95068 so there is more than only the new wastegate involved for a upgraded turbo Quote You need one or more of the following: more appropriate load request, throttle tuning, boost diagnosis adjustments. the goal is to have load = requested load even in part throttle with zero wg duty?throttle tuning even if the intake and throttle is stock? boost diagnosis adjustment means what? should boost follow desired boost in my picture by in a perfect world? i dont have stock car logs to compare with oem. Title: Re: negative deviation on part throttle Post by: aef on March 28, 2019, 12:57:58 AM load = load request
so nothing to change here? Title: Re: negative deviation on part throttle Post by: nyet on March 28, 2019, 10:50:03 AM negative deviation is boost, not load, and AFAIK it shouldn't even be enabled part throttle (although I could be wrong).
Don't look at load, look at lde |