I know, 670 seems pretty high, but it worked very good so far on my setup and i did it on purpose.turbo conversion wrote:Try lowering your cranking rpm to 200 rpm above what the starter is actually spinning the motor when cranking,
670 cranking rpm seems high to me.
The reason i set it "much" higher then the actual starter motor rpm is, that when i do, i usualy get max. 1 combustion on cranking PW, because as soon as the first cylinder fires, the rpm is pushed above crank speed and the following cylinders get the basic VE based on VE(N,MAP) * MAP * etc...
First of all this always gives a step down of about 20% (my normal VE is about 75-80% in that rpm range compared to the assumed 100%*crank factor while cranking) for the following cylinders, which again is a little different from start to start depening on temperature and rpm increase of the first firing cylinder.
When i set the crank speed higher, you archive that idealy all 4 cylinders get the same PW for the first combustion which gets much more consistant results.
Only drawback is, that MS goes back to crank mode when rpm drops below crank speed even if it was once exited. Some kind of state maschine would be great here, so you can reenter crank mode only via engine stop again. But due to this small drawback i had to find a compromise, but 670rpm works fine for me and i almost never get a "back to crank mode" in normal driving. Only when i push the engine down in gear or so, but this is not the case normaly.
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By the way, to answer my own question, i tried higher priming pulses with the same crank percentage and the starting time especialy around -10°C improved significantly! So i can highly recommend it. I would say, especialy if you run the traditional lower crank speeds and not all cylinders get the equal crank amount of fuel. Because priming PW will be always consistant too of course.