How to test the Ethanol % in your fuel - and when/why you should?

[Kenneth L Nielsen]

Guys,
If you have increased the performance of your vehicle (especially if you are running forced induction or an on the edge tune) and your car is not flex fuel capable, you need to test your fuels ethanol content. When I first switched over to E85 a few years ago, I had no idea that E85 being sold often only contains 60% ethanol... I also had no idea most 87-92 octane pump gas in my area contained anywhere between 0 an 10% ethanol - and why it would even matter.

Well, it does and here is a quick lesson in how to test and simplified reasons letting you know when/why you should.

 

[Chert_Detective]

I would highly recommend NOT doing any type of ethanol tune without a flex fuel setup specifically for that reason. It is too easy to wire up not to do it. Inline sensor, run power and ground. One wire pin to computer and you're good to go. AEM makes a great kit, I have it installed on my '08 L92 with a different sensor, that includes the sensor/gauge/wiring and is very easy to install and set up. It displays AFR and Ethanol content and. It be set up with failsafes for multiple parameters.

https://www.aemelectronics.com/products/gauges/failsafe-gauges/ethanol-failsafe-gauge-with-sensor

 

[Kenneth L Nielsen]

Very interesting! Would you mind shedding a little more light on how this product interfaces with the stock GM PCM to adjust fueling, timing etc., based upon ethanol content and perceived octane rating?

Thanks!
Toys

 

[Chert_Detective]

Very interesting! Would you mind shedding a little more light on how this product interfaces with the stock GM PCM to adjust fueling, timing etc., based upon ethanol content and perceived octane rating?

Thanks!
Toys

Even the non flex fuel NNBS trucks and SUVs still had the same E38 computer found in the later model factory flex fuel trucks and suvs. Because of this, all the computer needs is a signal from the sensor (oem equipment on the factory flex fuel vehicles) that carries the "Sir, I'm detecting this much ethanol" signal, and with a little table tweaking in HPTuners the computer takes care of the rest. Here is a good write up on how the sensor actually works.

 

[Kenneth L Nielsen]

ahhh. That is probably why I have not heard of it . The e38 pcm is 2006 and up. My 08 tahoe has it - but it is flex fuel anyway so I did not pay attention. My C5 is an 03 with the p01 contorller so I don't think this helps me for that vehicle much. Nice product though!!

 

[08z71bgm]

ahhh. That is probably why I have not heard of it . The e38 pcm is 2006 and up. My 08 tahoe has it - but it is flex fuel anyway so I did not pay attention. My C5 is an 03 with the p01 contorller so I don't think this helps me for that vehicle much. Nice product though!!

You might be surprised about that if you have hptuners and look inside the ecm. The 02-06 Tahoe vin Z was flex fuel. Most likely uses the same ecm as the c5.

 

[swathdiver]

Great video Ken. Federally, E85 can have an alcohol content anywhere from 51% to 83%. However, inside of this is the winter blend rating of E70 which covers 51% to 70%! So they can sell E70 during the winter and still call it E85.

Our motors like the stuff but standards are too lax, pumping ethanol is like a box of chocolates...

A big part of that has to do with introducing the new fluid with the old, and if the remaining fuel was E10, it will certainly reduce the content of whatever you added at the pump.

The filling stations around me forget to turn on their blender pumps during the day and leave them off overnight and quite often even in summer their E85 is still in the low 70s.

 

[Kenneth L Nielsen]

You might be surprised about that if you have hptuners and look inside the ecm. The 02-06 Tahoe vin Z was flex fuel. Most likely uses the same ecm as the c5.

Thanks for the follow up! I will have to take another look but I don't think my year PCM does have this capability.

 

[Kenneth L Nielsen]

Great video Ken. Federally, E85 can have an alcohol content anywhere from 51% to 83%. However, inside of this is the winter blend rating of E70 which covers 51% to 70%! So they can sell E70 during the winter and still call it E85.

Our motors like the stuff but standards are too lax, pumping ethanol is like a box of chocolates...

A big part of that has to do with introducing the new fluid with the old, and if the remaining fuel was E10, it will certainly reduce the content of whatever you added at the pump.

The filling stations around me forget to turn on their blender pumps during the day and leave them off overnight and quite often even in summer their E85 is still in the low 70s.

Thank you!!

It is kind of a pain, but the benefits are worth it - especially since E33 is enough for me. I go get 10 gallons from the station, test it, do the math and then add what I need to get to E33. Every couple of tanks I pull some fuel from the fuel rail of the car and test it to double check my work. It is always E33 +/- 1%. Watching the LTFTs is also a double check to any funky mixtures. Cheers!!

 

[swathdiver]

Thank you!!

It is kind of a pain, but the benefits are worth it - especially since E33 is enough for me. I go get 10 gallons from the station, test it, do the math and then add what I need to get to E33. Every couple of tanks I pull some fuel from the fuel rail of the car and test it to double check my work. It is always E33 +/- 1%. Watching the LTFTs is also a double check to any funky mixtures. Cheers!!

You know, I ought to do the same thing and run mileage tests again. So the Corvette likes 33% with your tune? Have you played with the Tahoe yet?

Had a highway run last year and alcohol was at 25% and saw the best MPGs ever at 71 MPH, 19.1 and climbing after about 90 minutes. Towing with E85, forget it! LOL