Join Date: Sep 2010
Location: Toulouse, France
Sorry guys but... You don't have to do anything to run on pure E85 on 2.7L or 3.5L engines, if finances is what you are looking for.
I often drive my 2000 300M on pure E85 and the only noticeable drawback is a slightly higher fuel consumption and some loss of power. E85 being half the price of regular fuel here, I can live with that.
A friend of mine drove his 1999 2.7L 300M on pure E85 until he sold the car last week, and same note... Less power, higher consumption, but less money spent at the end of the year in gas.
My brother has a 1999 3.5L 300M as a daily and runs on pure E85 too.
From what I read on 300M/Intrepid ECUs, they should be able to adapt to the percentage of ethanol/unleaded in the fuel, at least up to a certain point, based on the lambda readings.
However lambda is not used at WOT, the only compensation here would come from the fuel trims which should update themselves based on lambda readings while cruising.
One thing I found (or maybe I'm fooled by my mind) however, power losses come after a long "E85 driving period". It looks like power comes back after an unleaded refuel, and goes away after 2/3 E85 refuels.
If you are looking for performance, modifications will be needed. However, hardened fuel lines, pump... I don't buy ;)