Hi....had a friend show me his E85 running Nissan which has a GM ethanol content sensor feeding the AEM system. He said it allows his car to adjust the tune (timing) specifically to the fuel in the tank.


Is this overkill? I thought E85 had to be 85% ethanol if being dispensed at a pump by a major retailer?


http://www.ecmtuning.com/wiki/ethanolsensorparts




If not overkill...can the AP take in inputs from sensors not originally wired to the vehicle?

It looks like the sensor outputs a frequency signal.

The flex fuel sensor has a three-wire electrical harness connector. The three wires provide a ground circuit, a power source, and a signal output to the ECM. The power source is battery positive voltage and the ground circuit connects to an engine ground. The signal circuit carries both the ethanol percentage and fuel temperature within the same signal, on the same wire.

The flex fuel sensor uses a microprocessor inside the sensor to measure the ethanol percentage and fuel temperature, and changes the output signal accordingly. The electrical characteristic of the flex fuel sensor signal is a square-wave digital signal. The signal is both variable frequency and variable pulse width. The frequency of the signal indicates the ethanol percentage, and the pulse width indicates the fuel temperature. The ECM provides an internal pull-up to 5 V on the signal circuit, and the flex fuel sensor pulls the 5 V to ground in pulses. The output frequency is linear to the percentage of ethanol content in the fuel. The normal range of operating frequency is between 50 and 150 Hz, with 50 Hz representing 0 percent ethanol, and 150 Hz representing 100 percent ethanol. The normal pulse width range of the digital pulses is between 1 and 5 ms, with 1 ms representing −40°C (−40°F), and 5 ms representing 151.25°C (304.25°F).

The microprocessor inside the sensor is capable of a certain amount of self-diagnosis. An output frequency of 180 Hz indicates either that the fuel is contaminated, or that an internal sensor electrical fault has been detected. Certain substances dissolved in the fuel can cause the fuel to be contaminated, raising the output frequency higher than the actual ethanol percentage should indicate. Examples of these substances include water, sodium chloride (salt), and methanol.

It should be noted that it is likely that the flex fuel sensor will indicate a slightly lower ethanol percentage than what is advertised at the fueling station. This is not a fault of the sensor. The reason has to do with government requirements for alcohol-based motor fuels. Government regulations require that alcohol intended for use as motor fuel be denatured. This means that 100 percent pure ethanol is first denatured with approximately 4½ percent gasoline, before being mixed with anything else. When an ethanol gasoline mixture is advertised as E85, the 85 percent ethanol was denatured before being blended with gasoline, meaning an advertised E85 fuel contains only about 81 percent ethanol. The flex fuel sensor measures the actual percentage of ethanol in the fuel.

 

To my knowledge:

E85 can legally go between 70-90% Ethanol at the pumps.

No, The factory ECU cannot be set to detect fuel content regardless of who's tune you're using.

 

supposedly they had it in the works but i haven't heard anything recently, they have it for GTRs.

 

Isnt this called flex-fuel ?

 

Yes, that's what it's called. We had several North American car companies sell cars to Canada that were "flex fuel ready" but we have 0 Ethanol gas stations. Kind of made it an extra cost for nothing. It didn't last long here.

 

yeah that's the GM trademark for the ability to adjust their map based on actual ethanol content.




My query was specific to the Cobb AP as it seems to be the product of choice as of late.


But yeah...I guess if it wasn't a factory sensor then the AP wouldn't see it, unless a preexisting input was reassigned to read this sensor signal.


My friends AEM engine management has assignable inputs which require wiring up the sensor in question.

 

Sucks.


It is surprisingly popular near me in south east Florida.

Ottawa seems to be the only place in Canada listed here...

http://www.ethanolretailer.com/flex-fuel-station-finder

 

Cobb has been developing this for the 996/997, I know it's in progress, just don't know how far off it is.

 

I measured as low as E68 this winter and just ran my E85 tune (mega rich AFR but some knock)... and in summer I just measured E89 today (and loving it chief)

 

We will get there one day. We do it on the GTR now and the Subaru is coming soon.

This is something on the horizon, no ETA though yet.

Thanks guys,

-Mitch

 

What about E98 is it worth running it on race day ? ,i see there're selling it at the Shift Sector events from now on & would that need different tune than the E85 ?

 

Will take a pretty big fuel system to run E98, don't think many people will have enough pump or injector

 

would definitely need a tune for E98

 

Awesome news - The flex fuel aspect of the GT-R sure makes life easier for taking trips.

 

I can't even imagine trying to cold start E98 in the winter months