It's that cold time of year here in the Northeast. I realized this week that I had some interesting data on how the Motronic manages cold starting of the R1150s that I haven't seen elsewhere. I took some time and brought it together in a single Excel spreadsheet. The Motronic is quite an orchestra conductor.
Below is a graph that shows how the Motronic MA 2.4 with Pink Coding Plug manages the cold-start process. This chart was derived from some measurements I was making on the Yellow and Pink coding plugs, and it combines data from the GS-911 and the Innovate Motorsports LC-1. It may not be easy to digest at first but have a look at it and then see the comments beneath the chart.
Notes on Conditions
--The motorcycle was cold-soaked overnight and on its centerstand.
--Temperature in my garage was about 48?? F.
--Cold Start Lever in the detent position (which is 1.28?? open on my R1150RT).
--Battery fully charged, alternator came on-line immediately after start.
--LC-1 pre-powered so that it was measuring AFR at start.
--Closed Loop AFR at Lambda=0.94 which is 13.8:1 (Using Wideband O2 Sensor)
--Motronic MA 2.4 Pink Coding Plug (Yellow Plug may be different)
AFR: The first 25 seconds is very rich. At the end of the chart you can see it step to 13.8:1 which is when it goes Closed Loop.
Injection Time: I have doubled the time because each injector fires twice per combustion cycle. During the first 25 seconds (Start Up Enrichment) the Motronic dumps a lot of fuel into the intake--8 mS at first dropping to 4 mS by the time Closed Loop operation begins. After the first 25 seconds the fuel is gradually reduced as the engine temperature comes up. The injectors are very sensitive to battery voltage during starting. If the voltage is low the injectors don't spray enough fuel for a good start.
Spark Advance: Notice that the advance starts at about 11 degrees where it stays for about 2 minutes to help with the cold engine conditions. Then the advance is dropped into its normal idle range of about 6-8 degrees.
RPM: For the first 2 minutes, the RPM gradually rises, even though the injection time is being reduced, as the engine warms up. Then when the Spark advance is reduced the RPM drops even though the TPS is being held constant. Note that at that 127 second moment, in addition to dropping the advance, the Motronic lengthens the injection time a bit. The RPM gradually rises until the Motronic goes Closed Loop. At that time, RPM and Injection Time are stabilized.
Oil Temperature: I've divided the Oil Temp by 10 so that it fits on the graph. Not much to say except that it rises pretty steadily. At about 5 minutes (300 seconds) the Motronic goes Closed Loop. The Oil Temp is about 115 degrees. I don't know what combination of time and temperature the Motronic uses but it also must sense that the O2 sensor is operating, which it tells by O2 sensor voltage and resistance.
There it is, a symphony of moving parts. A lot has to work properly in order for the Start Up sequence to work well.