Another CL boost tuning help thread
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Another CL boost tuning help thread
Hey guys, I have been tinkering with CL boost the past week, it's 80-90% there, but there are some situations I'm still running into overboost issues. Rundown of details of my setup:
DIYPNP on firmware v3.2.5
99 Mazda Miata, GTX2867R with Tial MVS 38m ext. wastegate (5psi rated spring)
DIYautotune solenoid, plumbed to both port on the wastegate, like this (bottom diagram): http://www.diyautotune.com/images/pr...te_control.png
With boost control off, it holds a steady ~5.5psi to redline. Open loop boost control all checked out good, 100 = spring pressure, I can't remember the specifics, but lowering the values in the OL table increased boost little by little. I needed less than 50% duty cycle to hit my 225kpa target.
Moved onto CL boost, using the MS3 docs as my guideline, which I believe still totally applies to MS2 3.2.5, with 100 duty meaning 0 actual duty cycle = maximum wastegate opened. I did the tuning at around 4k rpm, per the guide.... I used 4000-4500 rpm as my starting point and found P and I values that worked well. At that point I thought I was done and good to do, but I ran into an odd issue when starting the "gear pull" from a low RPM- it would overshoot really badly. Below are screenshots of my setup and a datalog. In the datalog, I do a low RPM start, and you can see the boost duty does not increase quick enough, it overshoots badly and I hit fuel cut ~245kpa. Then right after, I show you how I went about tuning per the guide and how it works relatively well, hits target quickly and holds. I don't do it in the datalog, but it will hold steady till redline just fine.
Is this an indication that I need larger I values? I also have a problem of overboosting if I go from say 70% throttle in boost, then 100% real quick, it just does not react quick enough. Open to any and all suggestions. Looking to get it squared away before an event tomorrow. If I can't get it sorted, I'll probably just end up doing open loop, which is fine, but I do miss out on some low end/mid range power.
DIYPNP on firmware v3.2.5
99 Mazda Miata, GTX2867R with Tial MVS 38m ext. wastegate (5psi rated spring)
DIYautotune solenoid, plumbed to both port on the wastegate, like this (bottom diagram): http://www.diyautotune.com/images/pr...te_control.png
With boost control off, it holds a steady ~5.5psi to redline. Open loop boost control all checked out good, 100 = spring pressure, I can't remember the specifics, but lowering the values in the OL table increased boost little by little. I needed less than 50% duty cycle to hit my 225kpa target.
Moved onto CL boost, using the MS3 docs as my guideline, which I believe still totally applies to MS2 3.2.5, with 100 duty meaning 0 actual duty cycle = maximum wastegate opened. I did the tuning at around 4k rpm, per the guide.... I used 4000-4500 rpm as my starting point and found P and I values that worked well. At that point I thought I was done and good to do, but I ran into an odd issue when starting the "gear pull" from a low RPM- it would overshoot really badly. Below are screenshots of my setup and a datalog. In the datalog, I do a low RPM start, and you can see the boost duty does not increase quick enough, it overshoots badly and I hit fuel cut ~245kpa. Then right after, I show you how I went about tuning per the guide and how it works relatively well, hits target quickly and holds. I don't do it in the datalog, but it will hold steady till redline just fine.
Is this an indication that I need larger I values? I also have a problem of overboosting if I go from say 70% throttle in boost, then 100% real quick, it just does not react quick enough. Open to any and all suggestions. Looking to get it squared away before an event tomorrow. If I can't get it sorted, I'll probably just end up doing open loop, which is fine, but I do miss out on some low end/mid range power.
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