v1.3.1 boost control

[timgsxr]

Hi all,

So as I understood it boost duty percentages have been effectively inverted since v1.2. I upgraded my ms3 to v1.3.1 as although i have reasonably good open loop boost settings I could never get closed loop to work. So I upgraded firmware everything went well. Automatically I inverted my open loop boost duty table so instead of mostly 22% it was now at 78%. Went for a run and the boost ran at wastegate. Put my settings back to my v1.2 duty cycles and everything working again. Double checked and confirmed lower duty cycle = increased boost.

So all seems odd, did a quick try of the new closed loop "basic" slider did nothing but when looking at logs it seems as boost is dropping off the solenoid is closing up (wrong way round). So 2 questions:

1. Can I just invert polarity in the boost settings re-setup open loop to use 100% - old v1.2%.

2. Will the Closed Loop algorithm work when polarity is this way round, had a feeling somebody mentioned it wouldn't?

Thanks

Tim

[elaw]

Inverting the output polarity will do as you describe in open-loop - basically it makes the range 100-0 act like 0-100... did that make any sense?

But as you indicate, closed-loop will not work properly if the polarity is wrong. Basically what will happen is the control action will be reversed - the Megasquirt might try to reduce boost but it will instead increase, so the MS will try to reduce it more and it will increase more, and quickly go out of control. And of course a similar situation will occur if it tries to increase the boost.

Best would be if you could post .msq files and logs taken with both the 1.2 and 1.3 firmware.

[timgsxr]

So any ideas how change the polarity? Can I switch the wires around on the EBC or will that not work? Thanks

[elaw]

No, the only way to change the polarity is in the tuning settings. If one setting doesn't work, the other should. One thing you might try is to power-cycle the Megasquirt once or twice and make sure you exit and reopen Tunerstudio... I've got a vague memory of once or twice in the past having the polarity setting not "stick".

[timgsxr]

OK, so if I invert polarity the closed loop algorithm will still work. I'd heard it will only work if you use normal polarity? Will give it a go and get a log.

Thanks

Tim

[jsmcortina]

OK, so if I invert polarity the closed loop algorithm will still work. I'd heard it will only work if you use normal polarity? Will give it a go and get a log.

Yes it should work, otherwise there wouldn't be much point in that setting.

James