Hey guys

calling on all the technical experts to see if my theory wil work or if it’s just a wild idea.

Hptuners has flex fuel tuning capabilities so Im thinking if we can wire a sensor into the ecu/Sam to measure the ethanol content we would be able to tune it via hptuners

is this even possible?

when utilizing factory ecu's that have been unlocked by software for full tuning, generally speaking you cannot add additional inputs.

if you are able to re-write code you can repurpose an existing sensor to become a flex fuel sensor. you'll need to understand how to recode the map and its purpose. this is at times done to the secondary Oxygen sensor. this type of function has not been done for our computers to my knowledge.

Uh, so, what am I missing? Why don’t you buy an E85 kit and then go get a tune? Are you trying to avoid an E85 kit and wiring or something?

its a 85 dollar sensor vs buying the kit if it can work

I’m curious of how spending $85 for the flex fuel sensor alone, then finding someway to “wire it to the SAM/ECU”, then making the sensor work...
Compared to buying a $400 kit and spending an hour or so to install, no tune needed.

Maybe could be done. But this would require a large effort by a team.
So if you look at fueleconomy.org, some W204 were designed for E85. Once the option code is singled out, someone could search and find all the components of that system, including wiring harness.
The C63 was not rated for this.
So to begin with you'd buy all the wiring and sensor hardware off of a C350 I think. This is the end of the easy part.
Then you would need a team of people to have full access to the C350 ROM and explore all parts of the factory map, find all tables that deal with E85
Then those tables would have to be imported into the C63 ROM, which requires another lever of access. Modifying tables is one thing. Creating new ones is completely different. And yes, at this point, the tables are linked to a pinout of the ECU . If you have this level of skill and access, you may discover that the factory DID leave certain pinouts not enabled, for future use, just in case.

Anyway, team effort, unprecedented level of access, never going to happen. And if it did, those people are going to want to be paid for their effort, won't be cheap. If it did somehow happen however, it would be as close as possible to an OEM solution.

Which begs the question: Why DID they make the C350 E85 compatible?
Maybe in 2008 it seemed that this could be a wave of the future and E85 compliance could become a thing that the factory needed to be ready for. If this is the case, somewhere in a drawer in Stuttgart, there could be a ROM reflash that makes the C63 compatible and probably the cheapest most simple hardware to go with it as well.

Remember how they can figure out the tire pressure WITHOUT having pressure sensors, by the speed of the wheel, using the ABS sensors and how they could figure the compression without measuring the compression, by the speed of the starter?

I speculate that they can probably detect the ethanol without the ethanol sensor, there probably is a purely software way, so that if tomorrow legislation is passed that ALL US cars have to be E85 compatible, they can do a reflash with no cost to them. End of speculation.

thanks buddy

its more complicated than I thought

ordering my reflex fuel kit now