Originally Posted by CT335xi
Let me ask you a question, what are CATs? Is that the same as IAT's? Well if it is then your telling me that if your IAT was as high as 180 deg. that the timing corrections had nothing to do with det. or knock? I'm not saying the car was knocking, but the whole idea of the timing corrections is to prevent knock right? An the point I was really trying to make was that the e85 benifited him more then say 93 octane by itself where even more timing would of been pulled.
CAT(charge air temps) are the same thing as what we usually refer to as IATs. For me it is more accurate to talk about IATs as pre turbo and CATs as post turbo, but that's just me.
You are correct with your line of thinking, however in application it works a little differently. The DME follows timing correction tables that will target
lower timing advance the higher the CATs climb. It doesn't matter if you have 100 octane/e85/Q16 or whatever else in the tank the DME will still target less timing, it does this to prevent the CAT induced knock you're talking about because it assumes you have 93 octane. At that point, all the e85 can do is just prevent timing corrections.
That's why getting the BMS back end flash is a good idea, Terry(probably) makes changes to the correction factor tables to reduce the effect they have.