eniac

It's a fuel composition sensor.

The GM sensor part # 12570260 but is $350-500 depending where you get it from. I have heard of a cheaper version under $75, part # 12568450 but it's been discontinued by GM for the more expensive one(of course).

fast951

I looked into this a few months back. The resonably priced sensor would have cost in $350+ range (when purchased in quantity). However, I'm told that the sensors are not very accurate. On a NA car, you will get away with it, but on hi-performance turbo car, you will get in trouble. From what I noticed, most Flex-Fuel engines are NA not turbo.

Initially, I wanted to run a E85 sensor, feed the input to the DME and let it handle the blend. However, due to the cost of the sensor and the questionable accuracy, I opted to leave it alone for now. I think it's reasonable to expect a 951 owner to decide on the fuel he/she runs and select the mapping accordingly. I expect, 951 owners in areas where E85 is readily available, will use E85 most of the time.

fast951

This is what I found out. I have a contact @ GM, I'm hoping to get a sensor to try. The less expensive sensor was a old version, someone snatched a good quantity, haven't seen any on the market.

DanaT

I forgot to mention another important property of E85 that hasn't been discussed.

As I work in work in Boulder, many of the places where I go for lunch have special parking places for alternative fuel vehicles/hybrids.

I love taking a parking spot from a Prius!!!!

-Dana

fast951

The V-FLEX E85 will be a continuing development process. There are many variables that are still unknown. The Ethanol Blend %, summer vs. winter blend, different parts of the country or ROW??

DanaT

The sensor would be great. I am little lucky as E85 is available near where I work and about 10 miles from where I live. I can get E85, but one must strategically plan fueling. Sometimes its just not available and ratios aren't available.

The GM sensor, from what I understand, measures both alcohol content and fuel temp. It outputs a sqaure wave signal with the frequency giving the % alcohol and the amplitude giving the fuel temp. The ghetto method for determining fueling requirements would be to fuel up, drive for 10 minutes to get the fuel in the sensor, measure the frequency of the sensor output with a DMM or spectra analysis tool, and then adjust fuel pressure up or down (assuming not too much changed) based upon the mixture of gas to E85.

-Dana

anders44

we have saabs here, which are flexifuel, when ran on E85, they have more power than when fueled with regular gasoline

fast951

Using a E85 or fuel composition sensor will be great. However adapting it to earlier cars, such as the 951, will be a challenge. When everything is working fine, no problem. However when the sensor fails (and it will), how do we alarm the driver? On OBD2 cars, CEL will come on. On our cars, something must be developed which will be expensive on per unit basis.

I think leaving the decision of what fuel is used to the driver is more reasonable, at least for now.

eniac

All I would want is a switch to change over to normal gas if I ended up somewhere that didn't have an E85 station close by. I ahve ruled out doing this currently as it would be a nightmare with my Link to redo tune all the cells to switch between E85 and standard fuel (0-10%). I'd have to pull out the spreadsheet and go through and change each cell when I wanted to change fuel.

GM and other car manufacturers prefer to use a sensor because when speaking on the average consumer, leaving the decision of what fuel is used up to the driver, is generally not a good idea. lol. I expect everyone here would care more what goes into the tank and know before hand what it is.

fast951

I agree 100%, if you don't know the type of fuel you are using you shouldn't be playing with boost.

With the V-FLEX, you select (via a external switch) the type of fuel you want to run. The DME does the rest for you.

George D

Anyone care to share what they feel has to be done to allow us to run E85? Think of a manual starting with step one to startup.

eniac

Just swap out any old rubber in the fuel system and the fuel filter. That's about it. Then just need to tune it for the extra fuel and fill up the tank. You should change the fuel filter again after a couple short runs also.

George D

The only rubber left are the lines at the fuel tank. Those little short rubber ones. We have about five stations here selling E85. Do you think 1000cc injectors is enough? I ran out of fuel with race gas and 20 psi boost at 3 bar. I'll be able to have an E85 tune, a 91 tune, and a race gas tune switchable via laptop using the TEC GT.

Chris White, this is correct right?

Thanks,

George

95ONE

I have the 1000's (injectors) now for my projected 425whp. You may want to go to the next step up, which is to 1600's. They work great in honda's where they have a true sequential firing order. Do you have a Cam sync sensor for your Tech3 that will allow sequential firing of the injectors? If not, maybe stick to the 1000's.

E-85 only car. I have about 20 stations to choose from! And I truly won't be drivin this car to anything other than dedicated events or get-togethers.

You should change your new fuel filter shortly after installation because the E-85 will clean off the leftover varsol/petrolium film from the Gas tank liner. That stuff tends to clog the filter. After it cleans itself out. just change the fuel filter as normal.

I would change out any old rubber lines and forget it about them for a couple of years. Change out again then.

Bill

If you are going to change things, why bother with rubber fuel lines? Just make up a replacement set using teflon braded lines and AN fittings. Nothing you put into an engine will eat the teflon lines. I changed over when I started using toululene.