I was under the impression that the 97-03 f150's computers couldn't adjust the relationship of WOT fuel delivery to intake volume. (eg. couldn't compensate for fuel changes, or intake changes) (At WOT.)

But I've run almost a complete tank of straight E-85 through my truck and the wideband shows below 12 a/f at all RPM's of WOT. (I haven't bothered to change the relationship to ethanol) Please shed some light on this...

 

You are talkking ONLY at WOT? I would tend to believe what you do since your system is at open loop status at that point, so at least the O2 sensors are out of the equation. Your block might be running hot and the PCM is pumping more E-85 in to keep the block cool, and that would drop your A/F ratios.

BTW, how did your truck perform on the E-85? Unless I am mistaken, your truck is not a FFV, but that doesnt mean it wont run on E-85

 

stoich on e-85 is 9.7:1

 

Geesh! That sux!! That is why his A/F's are down!!

 

Stoic. for E85 varies between 9.5 and 10.1 E85 can actually vary from 15% gasoline to 20% or even 25% depending on weather and other factors. Cold weather demands more gasoline for cold starts and driveability. Maximum power at wide open throttle should be around 8.0 to 8.5 for E85 so I would say that you are dangerously lean. if you are at 12.5 air/fuel. You're engine will need approximately 30% more E85 than the amount that the computer is now delivering for the same amount of metered air to get to the safe operating range.

 

Be careful about jumping to quick. If the wideband is set to "calculate" air / fuel based upon 14.7 to 1 for gasoline, then the 12:1 is simply a calculation. Change the wideband to report based upon lambda. If you are truly lean, your exhaust temps will be high. Also, the post about the engine requiring approx 30% more fuel when burning E85 is inaccurate. Just because E85 has less energy when compared to gasoline does not necessarily allow us to immediately conclude more E85 is required.

Now over 45,000 miles since I re-programmed my truck for E-85 and fuel economy continues the same when compared to 93 Octane gasoline. Why ? Because E-85 burns much cooler and pollutes much less. "Calculated" stoich of 9.85:1 is not even close. I am running 25% lean (compared to calculated stoich) consistently with exhaust temps of around 1100 at 70 MPH....