Physical ethanol sensor speed?

[kbuskill]

So I recently installed a physical ethanol content sensor on my Burb and turned it on with HP Tuners.

My question for anyone that has an actual sensor installed from the factory or has done the conversion is, how fast does your sensor read the change in ethanol?

The reason I ask is I checked the ethanol percentage before turning on the sensor and the virtual sensor estimated it to be at around 15%, immediately after turning the sensor on in the tune it recalibrated to just under 10%.

I assumed the sensor would update instantly because of this but I left the truck running last night while filling the tank with E85 and watching the live data on the Torque Pro app and it didn't change after pumping 22.5 gallons of E85 until after I started driving the truck then it slowly made its way up to around 60%.

The thing I found odd is you could see the LTFTs go from about -2.34 to well over -20. While the truck was filling up which means the O2 sensors were seeing the ethanol content change but for whatever reason the physical sensor didn't seem to notice until after the truck was under a load.

Just curious if this is fairly normal or if you think something isn't correct. I just always assumed the sensor would be pretty much instantaneous.

 

[Fless]

Mine's an NBS with the OE physical sensor, and I shut the engine off when I fill the tank. It can take several miles (3 or so) of driving for the alcohol % to update and settle to a correct value.

 

[Marky Dissod]

Sensor works better if you shut off during refueling.

 

[Fless]

Read what @iamdub posted about it:

Ethanol percentage flex fuel

Perhaps you guys are right. It just seems kind of far fetched that I would be getting 30+% Ethanol in gas that each pump advertises boldly (less than 10% Ethanol), but I guess it would be a profit adder to the distributor if they decided to just keep adding Ethanol to the tank. It is easy...

www.tahoeyukonforum.com

 

[kbuskill]

Sensor works better if you shut off during refueling.

I tried shutting it off and restarting just to see if it made any change but it didn't, maybe it needs to be off longer, like the duration of fueling. I specifically left it running because I wanted to see how quickly it would sense the difference, which is why I was surprised when it didn't register any change.

Read what @iamdub posted about it:

Ethanol percentage flex fuel

Perhaps you guys are right. It just seems kind of far fetched that I would be getting 30+% Ethanol in gas that each pump advertises boldly (less than 10% Ethanol), but I guess it would be a profit adder to the distributor if they decided to just keep adding Ethanol to the tank. It is easy...

www.tahoeyukonforum.com

Perhaps I was just expecting more from a physical sensor than what it is capable of. I set it up in HP tuners the way they tell you to on one of the HP tuners boards, meaning I set the parameters to recalculate frequently, although I don't remember the exact settings at this moment and of course I am not near my laptop to check it.

I read what @iamdub posted but that seemed to be about the virtual sensor, which I assumed didn't apply to the physical sensor, but you know what assuming does, so I am probably wrong, or at least mistaken... lol

 

[Fless]

I believe that the PCM doesn't register a refuel event if the engine is left running during the refuel. I read somewhere that the alcohol content gets re-checked after it recognizes a refuel (more than 3-ish gallons added) but I don't have proof of that, and the actual measurement isn't instant. Besides, it takes a while for the ethanol to work its way through the system, to the physical sensor and ultimately to the O2 sensor readings.

 

[kbuskill]

I believe that the PCM doesn't register a refuel event if the engine is left running during the refuel. I read somewhere that the alcohol content gets re-checked after it recognizes a refuel (more than 3-ish gallons added) but I don't have proof of that, and the actual measurement isn't instant. Besides, it takes a while for the ethanol to work its way through the system, to the physical sensor and ultimately to the O2 sensor readings.

That is what surprised me is how my O2 sensors started picking up on it right away but the ethanol sensor didn't seem to.

I am glad to hear your NBS with a factory E sensor also doesn't pick up on it right away, at least it seems mine is acting "Normal".

When I saw the O2 sensors picking up on the change and the Ethanol content remained unchanged while fueling I was starting to think I did something wrong or had an issue somewhere.

I did turn on the settings for the MIL light to come on if there is a problem with the E sensor so I guess I should have known there wasn't an issue, but it still made me question myself.

Thanks for chiming in and putting my mind at ease.

I wonder if James @swathdiver has any more info on this?

 

[j91z28d1]

being you were idling with the fuel cap off, you might have just introduce a vac leak thru the evap system changing the fuel trims. in the same way pulling the clean side air intake tube to valve cover will change trims quickly.


also if you have newer non return style fuel system. I can idle for a decent amount of time on the fuel in the rail and lines. I don't believe I've read about much lag in the sensor itself, but there will be filter settings in the ecm code. there is for almost all inputs, hpt just doesn't define everything, either because it's not normally needed to tune, or not worth the work unless requested.

 

[Marky Dissod]

hpt just doesn't define everything, either because it's not normally needed to tune, or not worth the work,
unless requested.

I happen to know this to be true.
TunerCAT definition files the P01 / P59 Gen3 V8s have several tuneable parameters that HPT never will.
I very much doubt that HPT will bother to update the definition files of vehicles over a decade old.

 

[PPV_2018]

Just guessing here but i would think that it would take a little but of time / few miles or so driving before the sensor could pick out the exact mixture given that the fuel that it’s trying to read is a liquid that’s already diluted with other grades of fuel in the tank.

It’s not like it’s trying to determine a total amount of fuel in the tank like how a float gauge would give, it’s a specific amount of a grade of fuel it’s trying to determine. I don’t think the reading would be instantaneous like an 02 sensor.

But this could be totally wrong, i almost feel bad posting this skimming thru some of the more knowledgeable replies.