freedomgli

I'm running MS Labs Basic MS3 with Firmware 1.5 and Alpha-N control algorithm because ITBs. My MS3 only has one MAP sensor. Because I'm running Alpha-N I decided to use that for real time barometric correction since I like to drive in the mountains a lot and want to be able to handle elevation changes from sea level to 5390ft without fuss. However, with the update to Firmware 1.5 and the addition of Engine States feature I noticed that the MS3 thinks I'm in the Overrun condition when I'm actually at idle. Because I don't have a MAP sensor hooked up to my vacuum manifold, I have no way to adjust the Overrun MAP threshold parameter on the Engine States Settings dialog.

Consequently, I've had to temporarily disable the overrun fuel-cut feature so that my car will run at all. Is this something that I can tune around by adjusting the fast/slow accel/decel thresholds? Or is it hopeless since I don't have a MAP sensor and I'm not using VSS, either? How important/beneficial is the overrun fuel-cut feature anyway besides improved mpgs?

Pics for clicks
https://www.flickr.com/photos/addlightness/31725879136/

freedomgli

I can upload my msq and msl later but before when I was running 1.4.0 this wasn't an issue. It seems that something changed between 1.4.0 and 1.5 in how the ECU was determining overrun condition because immediately after updating the firmware to 1.5 this became an issue for me and I had to disable overrun fuel-cut.

Reverant

iTrader: (10)

I'm completely unwilling to even try 1.5 due to the engine states "feature". It is a "feature" that was never requested by any user, it was just shoved down our throats, because MAYBE it makes the code easier to maintain and support. I advise everyone to not update to 1.5 unless you have an extremely urgent feature that you need or a very serious bug fixed.

shuiend

iTrader: (24)

It broke ShadowDash and MSDroid also. I am not really sure why I upgraded one of my car's to 1.5. I have not noticed anything new in it that I care about that is better then 1.4.1.

freedomgli

The developers don't much elaborate on the bugs and other minor fixes in the readme. Since I'm at the very beginning of tuning my car I figured there's no time like the present to upgrade to the latest and greatest because bug fixes.....

freedomgli

So the recommendation is to backdate to 1.4.1 and definitely enable overrun fuel-cut?

aidandj

iTrader: (5)

It didn't break ShadowDash and MSDroid for me. Seems fine. I like the engine states.

OP post over on MSExtra instead of here. They will have more information for you.

Megasquirt Support Forum (MSEXTRA) ? MS3 Development (View forum)

afm

iTrader: (3)

Set the map sensor to the TPS signal so it fakes a map signal and triggers overrun at low throttle?

This pushes the problem to confusing overrun and idle, but that seems to be a problem that the devs are paying more attention to at the moment.

hector

Why run alpha-n at all? My car has been running fine in ITB mode for close to three years now on a DIYPNP and now MS3.

Install another MAP sensor to act as BARO also. I live in an area that has like 20' elevations at best but still decided to do a baro sensor so I dunno what would keep you from doing it since the ecu you have is more than capable.

And of course you can run without DFCO but why would you want to?

freedomgli

Thanks. I already posted MS3 1.5 Engine States Alpha-N in the MS3 General Support forum before you recommended the MS3 Development forum. I see this as a general support issue on a major firmware release, not a question about a development (beta firmware or future feature) issue.

freedomgli

Because Alpha-N gets most users ~95% of the way there with less effort and complexity than ITB Load Mode. Plus, you really need to start with Alpha-N and drive the car and log a fair amount of data in order to ascertain where the switchpoints should be before you can use ITB Load Mode anyways. I was thinking of trying ITB Load Mode down the road once I've got some more time and experience under my belt but I've got to learn to crawl before I can walk. And right now I just want my dad to be able to enjoy the car this summer even if the tune isn't 100% perfect.

Yes, this would be mandatory to use ITB Load Mode if I also want realtime barometric correction (which I do). Unfortunately, this requires me sending the unit back to Reverant in Greece (time, money, risk) or doing it myself (time, effort, risk), which I'm not 100% confident on since I have no formal documentation. Remember, I'm using a proprietary MS Labs unit, which is different than your run of the mill MS3X/V3.57. Can I figure it out? Probably. Do I want to mess with this right now? No, it's lower on my list of priorities.

This is why I asked. Other than slightly better fuel economy, what benefit does over-run fuel cut provide? I'm new to this so please pretend I know nothing other than what's published in the official MS3 manuals. The Setting Up manual says, "You are advised to start tuning with this disabled to avoid confusion."