Jody,Originally Posted by camcojb
They are talking about forcing the car into SD and running a 2bar MAP sensor without a 2bar os. It can probably be done, but it requires a bunch of tricks to figure out what you are doing. You loose lots of granularity and I honestly think you will be better off with a MAF on a car where you don't play with the boost controller too much. SD is great and all, but I don’t think it is worth it without the OS modified to have the extended map values in it.
Just to clarify, when the maf runs out it does not switch to the PE table. The PE table is always in play, it is what determines the demanded AF ratio (via the EQ) when in power enrichment mode. So when the maf runs out you use the PE table to demand progressively higher EQ values as the RPMs go up.
demanded AF = 14.7/EQ
So once the maf hits the last cell in the maf table (at lets say 5k), your PE vs RPM table will start ramping up the EQ ratio at a pretty aggressive rate. This will result in extremely low demanded AF ratios, but the resultant AF can be whatever you want. I could dig up some old examples from my blower car when I had a maf on it if you need to see that.
The thing you have to be careful about with this approach is boost spikes or any other dramatic changes in your setup. The tune ends up being pretty much hard coded once in that area where the maf is static. Most people just go real conservative to allow for plenty of wiggle room. You can get aggressive as you want on the dyno, but I personally dial it back to be fairly conservative unless I’m monitoring things very closely.