zok wrote:With EGR open, less oxygen enters a combustion chamber as if it would with EGR closed. Therefore start of ignition is more delayed as if there would be more oxygen.
On the other hand, air mixed with exhaust gases are warmer as if there was only intake air, so start of ignition is less delayed as if the EGR would be closed.
Anyway, less oxygen also means slower combustion process, so with EGR active, ignition delay is still longer than with EGR closed.
That means you should RETARD SOI with EGR closed.
But becasue an ori file is a very good and optimised compromise of settings for the cleanest emmissions possible, you could still advance SOI a bit in mid-range to get the best efficiency possible (but with more NOx in exhaust and far more work for a catalyst converter) and lower fuel consumption for a bit...
...but because you get start of ignition advanced a bit just by closing the EGR, if the rest of software is left in original state and you have no intention of doing a whole bunch of dyno runs while trying different SOI setups, then a very good option is to leave SOI maps intact.
I know, seems funny. :mrgreen:
But it's not. :geek:
p.s.: you get a lot more NOx also because of a closed EGR.
Thanks Zok why does Major say to advance the timing then?
I thought that I should retard too.
