Fun Facts:
1. FlexFuel as defined by the US Government.
Flex Fuel Vehicles
"Flexible fuel vehicles (FFVs) are designed to run on gasoline or a blend of up to 85% ethanol (E85). Except for a few engine and fuel system modifications, they are identical to gasoline-only models. FFVs experience no loss in performance when operating on E85. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 25-30% fewer miles per gallon when fueled with E85.1"
2. Can a tuned FlexFuel vehicle run on E85 fuel? Yes
3. Can a tuned E85 vehicle run as a FlexFuel vehicle? No
Quote:
Originally Posted by DJCarbine
As someone who accidentally flashed an E85 tune when running E10, the car will barely start/idle on the E85 map and the factory "wideband" was pegged rich.
Flexfuel compensation is a good thing.... why rely on LTFT to adjust your trims depending on the ethanol content when you can do a much better job with an ethanol analyzer and fill with whatever you please
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You bring up a very good point as I stated earlier small changes will adjust within the ECU especially for fuel but more drastic changes can have an impact as you have stated in regards to fueling.
Would you fill up your minimum rated 91 octane vehicle with 87 octane? Why not it is only a small difference of 4 octane points? Think about that, what is the concern? The ignition advance, timing, whatever you want to call it. A naturally aspirated FA20 engine with 12:1 compression is potentially more prone to knock events versus say a 8.2:1 compression Subaru STI Engine. As we have seen in knock corrections on many stock FA20 based vehicles, the Advance Multiplier will adjust in large steps due to the inconsistency at the pumps. So would you fill up
the random ethanol fuel of the day?
I personally prefer to create a map that gives the optimal performance of the vehicle while taking advantage of as many compensation tables as possible so that the ECU can calibrate itself to the conditions known by the vehicle's sensors. In my personal opinion auto corrections (correcting for incorrect fuel mixtures, timing values and boost levels) are a way of being lazy and potentially damaging a customers vehicle when relying on those built in safety features. These should be used as systems to protect the engine when needed, not as a way of tuning.
Example: Ken Block Gymkhana 1 Subaru
Ken asked during the filming if he could bounce the vehicle off the rev limiter under full throttle? (That was 8000 RPM) I said sure and he proceeded to gymkhana his Subaru around the segway and I suggest you check out the marks on the tarmac in that video.
When he came in, I pulled out my EcuTeK software plugged into the ECU and checked the Advance Multiplier which we all hope to see at 1.00. Well it wasn't, it was at 0.85. I was personally a little upset it was not at 1.00 but also amazed the ran flawlessly for him and glad those safety features protected the engine to the abuse it was put through.
Cheers,
William Knose