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

I have a MSII V3 latest code running fuel only on an otherwise standard RV8 3.5. I'm using the stock ignition (distributor) and cold start circuit (Bosch extra air valve) but with the cold start injector disconnected. Hot starting is ok.

A cold start - anywhere under about 15C - requires a deal of churning, but it does eventually start. When it does the warm up idle is fine. When I switch on I can hear the pump slow up after a second or so - so I'd guess it's pressurising the rail correctly. Opening the throttle slightly doesn't seem to help.

The enrichment is 152 at 0C and pretty linear to 100 at 71C. Pulse width is 10 at -40C and 2.6 at 71C. IIRC pretty well the defaults.

Big snag is of course knowing whether it is too rich or weak. The wideband sensor doesn't seem to give a consistent readout at cranking - even if I knew what the mixture should be for cold starting. ;-)

Dave,

You need to experiment with the -40C cranking pulse width. The cranking pulse widths need to be very close for the starting to work consistently at all temperatures.

If it is cranking and cranking and eventually starts, my first inclination would be to suspect that the cold cranking pulse width is too short. If it was too long, you would probably have to let it sit for a after cranking while before cranking again and starting.

So what I would do is change the cold cranking pulse width from 10.0 to 10.5, and see if that is better or worse. If it is better, I might try 11.0, and so on. However, if it is worse, try 9.5, etc.

Note that you only get one true cold start a day. It won't work to crank and start, then shut it off after a few seconds, then re-try thinking the engine couldn't have warmed up much. The reason is that there is now fuel in the manifold, the combustion chambers have warmed up quite a bit even from the few revolutions, etc. Also, you cannot use WB EGO feedback at all for cranking (it isn't even much use for warming up).

There is more here: http://www.megamanual.com/ms2/tune.htm#crank

Lance.