Yellow05C6
February 19th, 2016, 03:28 PM
I've been successfully tuning 411 VE maps for myself and friends for several years by just driving steady speed / throttle (it is flat where I live), logging fuel trims and adjusting the matching VE cell. Well I've moved into an '06 Z06. I understood the E38 to be more complex but I'm now confused. I added a CAI to the Z06 and thought I'd tinker with the VVE map before compounding the problem with headers. I've read several tutorials about the E38 auto calc VVE process; but those require a wideband which will not arrive on this car until headers are installed. I figured I could try my 'manual' way. So, on my favorite drive loop I disabled the MAF and captured about 30 minutes of data. To keep it simple, at about 1100 RPM & 44 kPa, I had a consistent LTFT +10.2% / +7.8%. The STFT is running negative numbers in the -5% to -10% range. The stock VVE cell number was 1721. So above the idle cell area I bumped the entire VVE map about 5%. On the subsequent drive loop, my LTFT numbers were nearly the same; but STFT has been driven more negative, now running -15% to -20%. The revised number for same cell is 1809. I've seen some notes about GM having a 'different' LTFT strategy for the early E38s. Can someone enlighten me?