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Discussion and questions related to the course Boost Control
I have watched this course and the electronic boost control webinar a few times and still not 100% sure i've got this right.
I logged a run with 100% DC in open loop to give me a idea as to what Boost i can expect to see at a given RPM. I've used these numbers in the closed loop boost target table. I also used these figures as the Y axis in the Wastegate DC table.
Planning on only running 16 psi (212kpa) so im unsure if i only need to to set the target table to 212kpa in all cells and the Y axis of the wastegate DC table to 212kpa. Below is a screen shot of my table.
Closed loop looks up the boost target on the Target table for a given RPM. Unless you want the boost target to be increasing with RPM, it should be 212kpa at all RPMs.
As part of the closed loop system operation, the ecu will reference the wastegate DC table relating to the RPM and boost target. Therefore, ideally the wastegate DC table would accurately reflect the wastegate DC required to deliver the boost target on the Y axis (ie, verify this with closed loop turned off). With closed loop turned on, this accuracy assists boost targeting (which comes from the target table).
As there are various trims that can be applied to the boost target, it is worthwhile correctly tuning the wastegate DC table below your target boost. I take it from your comment below that if you plugged in 100% to the whole wastegate DC table, it wouldn't deliver more than 16psi?
I changed my table and hopefully get time for testing tomorrow. I did a run with 0% duty cycle to see if my pluming and wastegate setup was right. I also did a run using 100% duty cycle it see how fast it would build boost, that way i know what im trying to aim for when setting up closed loop. I had the MAP limit set at 16psi for safety.
That's a shame. I tried to set up closed loop on the G4+ last night. Vehicle was a RB25, GTX3076 Gen 2, and external gate. I could not get consistent boost. I was getting exactly what Andre is describing. The only success I had was "half closed" or open loop and a table with MAP vs RPM axis.
I'm a bit disappointed - This is a major component of the ECU that needs to be sorted out even if the resources are being pointed towards the next gen ECU.
Post a log file please.
I'm using passive open loop and get a 4kpa overshoot at the point it reaches Max boost than a Max of 3kpa difference for the rest of the pull. No need for closed loop