Chips assume E-10?

Discussion in 'All Topics, Chips, and Tech for Buicks' started by Tom Kelly, Oct 24, 2019.

  1. Tom Kelly

    Tom Kelly Active Member

    Hi Eric, I was wondering about the pre-set fuel settings on my Turbotweak 5.7 chip. (22 lb. boost with 60 lb injectors) Now that I have a wide-band sensor and gauge I can see that it idles in gear at about 13.9/1 and generally likes to be just either side of 14.71 (up o 15.0/1) in normal operation, dipping down to 13 under load. I was wondering when you pre-set fuel demand did you assume E-10 fuel. I ask because I understand that “Stic” for E-10 is closer to 14.0 while 100% gasoline in 14.7. Am I running too lean at 14.7? How does all that work? Thanks
  2. EricM

    EricM Administrator Staff Member

    A wideband gauge calibrated for gas will always read about 14.7 when the fuel mixture is at stoich, no matter what mixture of ethanol. So during cruising, you will see around 14.7 give or take. At idle, I program the chip for open loop, so I can deviate from stoich, a tad richer, around 13.0 to 14.0. So everything is working correctly.
  3. Tom Kelly

    Tom Kelly Active Member

    So the wideband sensor sees that the mix is exactly at stoich and, because it is calibrated for gas, the gauge reports 14.7? So 14.7 might not be the actual A/F ratio but the gauge is really just saying that the ratio is at stoich (about 14.0 for E10)? In other words the actual A/F number displayed is not accurate with E10 but it doesn't matter because in any case the lambda is still 1.0?

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