Turbo_Terry

Is the MS3 boost control strategy any better than MS2?
I've been getting increasingly fed up with attempting to calibrate the closed loop boost control on my MS2.
I can not get the controller to hit the boost target consistently in every gear. Also settings that seem to perform okay one day, will be completely wrong the next day.

Open loop control works perfectly 80% of the time, but it needs re-tuning for colder/hotter weather or different atmospheric pressure. This is what closed loop should do!
Its like megasquirt totally screwed up the boost control with the MS2. It should use the open look table and apply a PID to that with a clamp on how far the duty cycle can be altered from that initial figure.

Anyway, I'm getting increasingly annoyed with this garbage MS2 boost control and was thinking of changing to an MS3 as the control strategy is different.
What are people's experience with calibrating closed loop boost control with MS3?
Is it still better than MS2?
Is it worth upgrading to the MS3 for the boost control alone?

Ted75zcar

iTrader: (2)

The MS3 is different than the MS2, there are other threads that discuss the differences, so I encourage you to search them out.

I have been working towards an improved manifold pressure control system for several months. Bottom line is that none of the MS variants have a control system that is sophisticated enough to meet my performance requirements. At a high level, I am targeting accuracy, precision, stability, and response time over the entire dynamic range (WG to All-of-it), under all operating conditions.

I posted on some of my early work starting here:

https://www.miataturbo.net/build-thr...4/#post1452934

One tip I can provide is that If you are on an NA platform, and truly want improved performance, you may benefit from going to an NB style alternator and MS based voltage regulator.

Good luck!

18psi

iTrader: (76)

ms2 = terrible
ms3 = works

I don't even bother trying to get cl boost to work on ms2

Turbo_Terry

Hi Ted,
I looked through your thread, but I'm not an electrical engineer and I'm afraid the vast majority was way over my head.
As you have proved, there are some hardware and electrical limitations with the megasquirt. But as open loop boost control works pretty damn well for me I don't share the same concerns.
I believe the issues I'm seeing are due to the poor control strategy employed by the MS2.

Turbo_Terry

I've done some research into the MS3 and I'm reading reports of people having the same issues with boost control that I'm having with my MS2. Looks like MS haven't developed a robust method of closed loop boost control with their newer model.

Bronson M

iTrader: (1)

Keep digging, MS3 boost control works just fine. Could there be improvements? Sure, but none of the ms2 problems have carried over.

Ted75zcar

iTrader: (2)

Per the MS3PRO gen 1 manual (and probably other MS3 variants), the MS3 uses a new bias value as a feedforward for each load cell transition. The Pro hardware has a 36V flyback clamp. These two factors alone will improve performance dramatically.