Yes- i manage several E85 stations and a friend's GM shop told a customer of mine that the fuel was the problem (tested E95). This was before we knew that GM had an issue with their '06 Impala algorithm to calculate fuel ethanol %. The Kent-Moore test kit for alcohol was new to the GM shops at the time.
I quick reviewed the load rack's manifest (where E85 is blended), it was dead on, so I asked the shop to get me a sample off the fuel rail. Sent it to the state's lab along with the station's sample. All came back dead on. When I continued to look into it was when I found the Kent-Moore test is very very time sensitive due the sample being so tiny. (I have stored 5 gal in sealed containers for months with no issue- but a few drops in a big room of air changes fast). BTW- I later had the algorithm issue on my '06 Impala, and just had a similar fuel complaint the other day- to no suprise- the problem car was an '06 Monte Carlo with the same algorithm problem. GM wrote a PCM flash for these 3.5L ,06's when the complaints rolled in. The flash works and is free. On my car it showed up 5 miles after filling the car- symptom is an extremely hard, loud shift and later a CEL. On mine the PCM's published alcohol content was 16% when actual was 78% (fall blend).

OP--You should have no problem with the unit you bought when tied into a factory alcohol sensor (that were used in pre-algorithm type cars). The issue I just talked about arose on later model cars where they eliminated the real alcohol sensor and began to only read other parameters such as tps, o2, trims against maps, etc, and then back-calculate (estimate) what you put into the car for fuel.

 

AH, the newer GM flex fuel cars ditched the flex fuel sensor and is calculating ethanol content based on wideband readings?

 

BTW, that's a sick car!

 

I think they do it on fuel trims and some other misc readings now.

- Bryan