Hondata

Hey guys. My e85 content reading seems low. I have drained the 93 and filled up with e85 multiple times now. I have ran straight e85 and test it before pumping it into the car and it always test at 90-95%. Why is my e85 content reading only at 78%? Today after I filled with e85 it was reading 81% and dropped back down to 78%. Any ideas what would cause this?

Thanks, Ed

How are you draining the tank?

Probably because E85 is not 85% ethanol. Where are you seeing 78%? That's what I get in CA year round.

Spunkster wrote: Mon Sep 14, 2020 9:12 am How are you draining the tank?

I disconnected my fuel line and ran it into a VP can several times. Also by driving the car the car and then filling up with e85.
Thanks,Ed

Hondata wrote: Mon Sep 14, 2020 3:13 pm Probably because E85 is not 85% ethanol. Where are you seeing 78%? That's what I get in CA year round.

My krpo e85 content is is reading 78%.

Thanks, Ed

This is what I have been filling up with nothing lower.

The flex fuel sensor does not measure the ethanol content, it measures the capacitance of the fuel that passes through it. They are designed to work with mixtures of regular gasoline and ethanol with blending ratios found at the pump. The accuracy that is required for an OE flex fuel vehicle is not great, perhaps +-10% on the ethanol reading is fine because that would only be a fuel trim of 3%, which the fuel trims would take care of.

So there are several things to consider here:

- what is the actual ethanol content E85. E85 can be 51% to 83% depending on location and time of year. If you test it at 95% then it indicates there is something wrong with your testing method.
- what is the actual ethanol content of the fuel in the tank. You can never drain the tank fully unless you open it up and clean it out.
- most flex fuel sensors has a claimed accuracy of +-5%
- the effect of other components in the fuel on the capacitance (permeability) of the fuel.

The last is a bit of wildcard because there are a lot of different molecules in gasoline, all with different permeability. Methanol, water etc are going to affect the reading. BTW E85 has about 1% water in it.

The interface from the sensor to the KPro is digital. I'm pretty sure the KPro is just reading what the sensor is telling it.