info on E 85 tune

[Sburn]

Originally Posted by JackandJanet

Nice point, Sburn! I vaguely remember someone posting that there WAS a sensor somewhere, but I don't think I ever saw anything more about it (so it got filed in secondary memory).

It really makes sense doesn't it, that if one of their vehicles has the sensor, all flexfuel ones would have it? I guess Bill would know for sure, or, perhaps one of the techs on the forum?

- Jack

OK, so I did a little digging on this starting with my 2007 Ford F150 Wiring Manual and the Powertrain/Emissions Manual. No mention of a separate FFV sensor in either. Only slightly different wires for fuel pump and fuel gauge with FFV options are shown. NO PCM inputs for a FFV sensor.

So more digging on Google seems to suggest that Ford went away from the fuel line-style FFV sensor sometime around 2000.

Looks like Ford now does the calculations all in software with the only hardware change being a wideband oxygen sensor in place of a narrow band oxygen sensor in front of the catalytic converter(s).

Best as I can wrap my noggin around it at this late hour is that the PCM, via the wide band O2 sensor, always tunes air/fuel ratio for a lambda of 1.0 A lambda of 1.0 indicates complete burn, irrespective of the fuel used. So with the PCM software always tuning the AFR for a 1.0 lambda for whatever gas/E85 mix is being burned, you get a Flex Fuel Vehicle pretty much via software.