Quote:
Originally Posted by Ilma
Yup......finally got it - Thanks!
Lesson learned......know what your datalogs really mean.....the numbers are not always real.  |
Also keep in mind that some of the piggy tunes like to run these engines on the lean side. I recently put my N54 335i and a friend's N55 135i on the same dyno for a few back to back pulls. My car was running Cobb's E30 "race map" with the AP, and my friend's car was using the JB4 stage 2 (I think). Both cars were running ~30% ethanol. The wideband 02 on the dyno was calibrated for ACN pump gas. My car showed consistent ~12.0:1 AFR on all pulls. His JB4 car was in the 14's through most of the powerband, then went way fat up top. Different tuning methods produce different results. I much prefer the Cobb approach.
I'm not sure what the exact stoich value of E30 is, but I'm guessing it's in the mid-13's. Of course, when I'm logging at idle and cruise, my datalogs show mid-14's for AFR.
One of the great things about the N54 is it's closed-loop WOT fueling. While it doesn't know how much ethanol you have in the fuel (unless you add an aftermarket sensor/kit), it sees the need for more fuel being needed to meet it's lambda targets, and can correct via the fuel trims. Obviously, this shouldn't be used as a Band-Aid for proper tuning, but it can compensate for variations in ethanol % from tank to tank.