MicroSquirt.com read only forum (Jan.15,2018)

Hello, I am running a cb750 honda motorcycle with a microsquirt Ver1.0 for fuel only. Tach in is from tach output of dyna2000 ignition, square wave into opto-in. This was was working pretty well with 2.886 firmware but would start hard from time to time, so I decided to try 2.890 firmware. I can not get it start with this firmware at all, tried starting from scratch no go either. The required fuel with 2.886 was around 4.5ms, with 2.890 it comes out to 10 ms with same constants. The box for setting blend high, blend low is gone also. Tried changing the blend to settings to the opposite, no joy. I read up on the changes in 2.890 and I dont see anything that would effect my setup. Also when I switched back to 2.866 to confirm it would run on this, I had to set it up for sd at low rpm and switch to alpha n at 1000rpm to get it to start again. Attached is the MSQ's for each. Any help would be appreciated.

Tom

There are many differences between the 2 files, some which aren't critical and some which could explain the problems. I will check it out on the bench tonight.

Ok thank. I checked my settings again when you said there where differences and you where right the req fuel was 10 on the 2.886 vers. I reset it to 4.4 ( with the req fuel calculator ) and it wouldnt start. Moved ve bins up 10 and down 10 still wouldnt start. Set reg fuel to 10 manually and moved ve table back to original and fired right up! Did some experimenting and would run down to 5 req fuel even without moving ve bins, but not below that no matter where i set ve bins. So next I loaded 2.890 and set req fuel to 10 and imported ve table from 2.886 and it runs Know I guess the question is why wont it run below 5 required fuel, the lower the req fuel the higher the ve bins need to be to get the same pulse width right or am I completely confused on this basic concept?

The pw = Req_fuel * VE * other stuff + topen, so yes changing VE to compensate for a lower Req fuel should give the same PW and the engine should run the same if PW is the same. But there are 2 Req_fuels shown in MT, one may be grayed out and I am not sure which one gets sent back to the processor. So compare the gauge PWs for the 2 cases and if they are the same but the engine runs differently, that would scare me. But I don't think this will be the case unless something else is different in the msqs.

The greyed out one changes to the same when I tab out of the first. I will experiment with this some more when I get the chance. My 5 year old is home from school and it's kinda hard to concentrate

Ok, finally got back to this. Working as expected now, think I got bit by not tabbing out of fields before burning changes. Pulse width is around 2.3 ms at idle and having trouble with not enough resolution.

Did you manage to get it to run on AlphaN

I couldn't get mine to run AlphaN