Open Issues ToDo
Q: Has anyone experienced problems with poor table lookup performance?
Bill, im very intrested in this problem, is this something you also see on the pre-compiled (recent) releases ? I know we have had some issues with different avr-gcc versions in the past, make sure you are using the recommended version (see WinAVR), but anyway thanks for the report i will look into this - DB
A guy here in Sweden has reported a similar problem but related to ignition. With a steep ignition map in the idle range he said that he got a strange spark behavior, he claimed a problem with the interpolation but never made a report that allowed us to recreate the problem. I suspect that this can be related. -Jörgen
Jorgen - we too saw the problem initially several months back while trying to use timing controlled idle. Bill
I have installed pre compiled firmware .53. The firmware has a problem interpolating in both x and y as can be seen by
http://www.lolachampcar.com/images/53%20map.pdf
http://www.lolachampcar.com/images/firm53%20rpm.pdf
http://www.lolachampcar.com/images/53%20map%20and%20rpm.pdf
http://www.lolachampcar.com/images/53%20VE%20Table.pdf
I have used unrealistic VE values to highlight the abnormality and to ease my understand of which cell values are being used in the averaging at which times.
When you are on cell, the index picks that cell and the next highest while the weighting favors the ohter direction. Change search_table in helpers.c as follows-
if (item <= tbl[i]) { // was just < which may be causing VE lookup problem
I have tested this and it fixes both RPM and MAP VE lookup problems (and probably timing and Lambda as well). We will be testing more on the dyno today.
Bill, thanks for your extensive testing, how did the dyno session (of the reported fixed helpers.c) turn out ? Do you have a pdf of the same simulations after the fix ? Regards Dave - DB
We just finished a run of EPA emissions testing. We can now hold VE which in turn allows us to hold a constant torque on the brake and thus hold EPA testing set points. I will run some After PDFs tomorrow morning and post them but the "=" made all the difference in the world! You would not believe how smooth the engine ran and overall emissions spectrum was down almost 20% while with the same target lambda. Bill
Good RPM Sweep http://www.lolachampcar.com/images/good%20rpm%20sweep.pdf
Good MAP sweep http://www.lolachampcar.com/images/good%20Map%20sweep.pdf
Please save copies of any pdfs you may want as I will be clearing them from my site in a few days. Is there any reason to leave this post up much longer?
An example of how CWL, CWH, AWEV, AWEV_Temp..., and AWC affect cranking and afterstart can be found at MembersPage/BillHart/CrankingAfterStart.
Recent Questions:
MembersPage/BillHart/ProblemHistory for older issues that have been resolved.
Projects Underway
MembersPage/BillHart/WinMobileLogger The logging dongle (logging without a PC) and smart tuning tools have been combined into a complete system. This system applies to tuning any fuel control but works very well with the GBV3. I have a note into Marcel to see if there is anything we can do with VEMS to make this available.