In this episode, Aaron tests the narrowband Air/Fuel gauge he bought and hooks it up the the extended wire from the O2 sensor. He also gives a couple updates on the legacy GT turbo build.
A narrowband AFR gauge isn't the best method to measure your air/fuel ratio, however it does function as a good idiot light to let you know if you're about to blow up your turbo build! The lower the number, the richer the mixture. The higher the number, the leaner the mixture. Stoich is 14.6-14.7. Tuners generally like to see the AFR's in the mid-high 12's at WOT on a turbocharged engine so you don't get detonation.
With this car being un-tuned, Aaron is relying on the factory ECU and MAF to accommodate the extra air being pushed into the intake via the turbo. The factory electronics do a pretty good job and AFR's on the Legacy GT hover at 13.0 at WOT. While this AFR isn't the ideal, it seems to be holding up alight.
He is planning on installing a wideband O2 sensor and gauge in the future to better monitor the AFRs. There are also plans to increase fuel at WOT in the future to ensure safe fuel ratios and a reliable daily.
