FlexFuel Composition Sensor -> Comp table for Dig2 input

[Carlos Iglesias]

Request a compensation table to use as a baseline when adjusting for ethanol percentages. Intention is for OEM (FlexFuel) Fuel Composition Sensor freq. output to provide input to Dig2 for fueling adjustment.
http://www.efi101.com/forum/viewtopic.php?t=5928

[TunedByShaneT]

Cant you use the 2nd load table?

[SprinterTRD]

As long as he has advance tuning enabled in the ECU Shane T is correct.

Configure dig 2 as a speed input
In "General setup" "Miscelleanous setup" set Efficiency 2 calc method to 7 (dig 2 frequency)
Fill in the secondary fuel table to end up with the correct AF ratio.

[yotamhks]

can these sensors "sense" other changes like adding methanol into fuel tank?

[TunedByShaneT]

Depends which one you use.

The Delphi one I used was like <100 Hz = Straight Gasoline, 101-200 Hz = % Ethanol 200 being 100 % and > 200 methanol.

[yotamhks]

where can it be bought?
what about 10-15% methanol and 85-90% pump fuel?

[TunedByShaneT]

The Sensors are available through GM and I sell them on my website - They are prohibitively expensive 600.00 USD or more. From memory, they are not intended to measure the amount of methanol percentage - they are meant to go directly to 200 HZ if methanol is present. In practice, this can still be useful if you will be running multiple fuels. When I was playing with these sensors (2005-2006) we were using them to run Pump Petrol, E-85, Race Gas and Methanol without the driver flipping a switch, however we never intended to mix the above together. The sensor actually gave slightly different readings with pump petrol compared to Race gas. That may have been because the Pump Petrol here in the US almost all has some percentage of ethanol in it, where race gas had none.
http://stores.homestead.com/FASTMotorsports/-strse-Sensors-cln-Fuel-Type/Categories.bok

[Carlos Iglesias]

Shane, thanks for the contribution to my question. Always great to have someone I consider one of the "pro's from Dover" add to a discussion.

Unfortunately I just realized that my initial intentions were infeasible. Paul Yaw, who is graciously programming the M4, is using the secondary load table for RPM/EMAP, so I will not be able to compensate for fuel composition directly. Sonsing will just have to do until I get an ECU from the last decade. So next weekend I plan to see if I can atleast feed the Fuel Comp Sensor signal into the AIM DASH. At least it will add to my awareness.

However, my orignal question still stands: how would I map out fuel compensation for Gasoline/Ethanol mixes if I start with a particular percentage of Ethanol. Will I just have to completely map an E85 mixture as well as map a straight gasoline mixture and then extrapolate any mixtures inbetween? Or perhap the simplest solution is to just map E8x and then always custom mix the pump fuel to that standard.

Just trying to think ahead how to best maintain the right fueling for an "E85" dyno'ed map that tends to vary by season and pumps.

[Holmz]

I thought that those sensors gave %-age of ethanol.

So same question... but with an M800 what would be used for both the mixture as well as the spark advance?
Is it just a 1D table (Scale factor) for the mixture?
and is the advance a 2-D or 3-D table?

<more added 24-Jun-2012>

It looks like the half way down the page http://www.megamanual.com/flexfuel.htm it says 50-Hz for pure gasoline/petrol and 150-Hz for ethanol, and all numbers in between are pointing to %-Ethanol = sensor-Hz - 50Hz .
In the same picture it says 1.59 correction factor for 100% ethanol, starting at 1.00 for pure petrol/gas.
So is there anything special that needs to be done? Or just bring into an analogue input or a digital one to get the frequency?
And how about the pulse width for the fuel temp? (How to get that data into the m800?, and what to do with it once it is there?)

The simplest approach would be the 1.59 correction factor.
But the cooling of the air charge seems that it would be temperature (and maybe air pressure) dependant, so should a 2-D table be used to provide more enrichment for injectors that are on the air filter side of the throttle plate?

And is there any resources on where to start with the math on the evaporation/cooling?
And again what should be done for ignition advance?