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Help-do Ethanol Content Sensors Read Methanol?

sky30

By sky30,
in Engines & Forced Induction

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GTSBoy Grand Master

GTSBoy

Posted
Posted

It's more than likely that they do. They'd be based around the idea of detecting the -OH group on the ethanol, and so should be able to see the same group on the methanol molecule. I would be VERY HESITANT to trust that the % it read out while seeing methanol would be accurate though. I'm sure that there are some calibration factors assumed/built into the sensor or its calculation that would be thrown out by the lighter metho molecule.

GTSBoy Grand Master

GTSBoy

Posted
Posted

I just googled around a bit and there is muttering that the usual suspect sensor (the GM/Haltech one) tends to go to 200Hz frequency when methanol is present - meaning it is not useful. This is not the final word, as I'm not going to do all your research for you, but it would appear that whilst methanol will affect the sensor in a similar way to ethanol (as I suggested in my first post) the actual response of the sensor to the difference between eth and meth is to say that >100% ethanol is present. This is probably the safe and conservative way to do it, because methanol requires a lot more volume than even ethanol does, and system/sensor designers would probably want to be able to protect themselves against people using methanol deliberately/accidentally and running too lean.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Lol, easier to carry a flex fuel sensor

I agree, until such time it lets you down.

I was told these sensors are actually reading what percentage isn't ethanol, not sure how correct this is.

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

How many have you seen fail, Scott?

None, and I assume they are fairly reliable seeing they are used in OEM applications, but they are also monitored by the stock ecu, and there are huge safety margins in place. I don't think I could ever fully rely on a sensor like this for turbo tuning unless I had two of them to compare. The less variables in the tune the better imo.

Same goes for wideband target mapping, without a pair of sensors running simultaneously you would have no idea if they are accurate.

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

I agree, until such time it lets you down.

I was told these sensors are actually reading what percentage isn't ethanol, not sure how correct this is.

But most ECUs have a failsafe, so if the ethanol sensor fails then assume ethanol content is 0% or whatever you set it as.

I'm running a flex sensor now too, drove to Wakefield yesterday with four jerry cans. After the track day, drove to 7-11 and filled up with 98 and drove home.

And unrelated, I chopped two R34 GT-Rs down the straight at Wakefield...

scotty nm35 Grand Master

scotty nm35

Posted
Posted

I'm running a flex sensor now too, drove to Wakefield yesterday with four jerry cans. After the track day, drove to 7-11 and filled up with 98 and drove home.

We did the same thing in Artz's 33, other than we had to drop the petrol tune on with the laptop near the border. A simple switch would have done the job.

Doesn't make much difference, you still need two tunes, but I can see the practicality of it.

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Yeah but make a perfect 98 tune, then all you do is interpolate between the E85 3D map based on the ethanol content.

I drove home on about E40.. got mad economy too, did 187km on 20L

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