MoTeC Global Forum

I have a MAF based system on a BMW M54B25 6 cylinder.

I am having problems with getting the cranking and cold start ironed out.

Does any one know which point on the main fuel table is used for the first injection and cranking comp?
At what point (rpm or other condition) does it start using other points on the main fuel map? (cranking to post start comp change over)

On the factory ECU it is all in ms injection times, not % like in the M800 I have.
In the factory ECU (MS42) I can get a sharp start(easily under 1 second to running) but with the M800 it takes 2-5 seconds to catch(fully charged Optima D34/78 @15V)

Thanks

On main fuel table it would be the cells that are closest to cranking conditions. All the start/cold start fuel is on top of what the main fuel table is telling it to do. Set main fuel table to values that result in decent warm/hot restarts then go from there.

Make sure your MAF cal is giving you rational readings at cranking and 0 RPM, and not reading zero or excessive fueling, or going into fault and reverting to fault value. While normally a MAF results in a very flat looking main table, keep in mind the table values in the main fuel table below idle at 0 RPM and near cranking RPM may need to be much different while the rest of the table is flat, you don't get a good steady signal during cranking.