Wednesday, January 18, 2017

The Smell of Drunken Hobos

Most people experiment with alcohol during their college years, and I was no exception. Where I differed was just how I experimented with it. While most of the rest of you were drinking low-level poison in quantities that would cause a cow to vomit out all four stomachs, I was burning it by the barrel. 

I lived across the street from a gas station that had one of the three E85 pumps in the state of Utah. For those not familiar with E85, it is a renewable fuel manufactured from the unfulfilled campaign promises of presidential primary candidates in the state of Iowa. The reason it is of interest to automotive enthusiasts is that it has an octane rating of approximately 105 and generally costs less than regular unleaded. When I lived across the street from an E85 pump, I ran my turbocharged Ford Ranger on E85 so that I could continually replace engines run more boost. 

In those days, if I wanted to run some mixture of gasoline and E85 instead of just one fuel, first I had to estimate the percentage of ethanol and percentage of gasoline. I had an excel spreadsheet for estimating the mixture, so after fueling, I'd pull out the laptop, estimate the mixture, and then connect to the engine control unit and change a fuel injector parameter. One time after changing that parameter, I was driving down the freeway and I received a call from my little brother, Marvin. He asked where I was, and when I told him, he let me know that he was about 3 miles behind me and could still smell the sweet scent of overly rich ethanol exhaust (which I actually kind of enjoy). As you can see, my methods weren't exactly sophisticated, but then again, neither was I. These days, I'm far more about 7% more sophisticated so I decided I needed a 7% more sophisticated solution for running ethanol mixtures. Enter Ford Taurus... wait, what?? 

As I've already shown, the Ford Taurus is an excellent car... ...for stealing parts from.  This time, I stole a flex fuel sensor from a Taurus. Flex fuel sensors have been fitted to a number of vehicles, mostly domestic US vehicles so that they could get a CAFE credit reduce emissions and save the world. With the sensor in hand, my first task was to mount it.

Junkyard treasures
Beginnings of flex fuel bracket

Mad decent aluminum welds

bracket installed
Once I had the bracket made and installed, I had to slightly rework the fuel system. Originally I had the fuel system setup as a deadhead style fuel system. I could try to explain it, but I won't. There's a drawing below, you lazy clod.

Legend says that a flow through fuel system is better than a deadhead system. Apparently the fuel doesn't soak up as much heat when it is able to flow through the rail. I think there are some other benefits as well, but honestly, I don't remember what they are,

With the sensor mounted, and lines run, I turned my attention to the seals on the sensor. There are two versions of this sensor, one for Ford and one for GM. The Ford version has threaded inlets and outlets, while the GM version uses barbed pipes as inlets and outlets. Using the Ford version allowed me to maintain consistency with my -6 AN fitting system I had used throughout my fuel system. The problem I ran into was that I was afraid the teflon washers I was using to seal the fittings would not hold. After a quick search on the McMaster-Carr website, I found just what I needed. I also learned that McMaster-Carr is only about 15 miles from me, so I went and picked them up rather than placing an order and hoping that they wouldn't charge me $90 to ship a pack of $3 washers.

teflon washers
bonded steel and rubber washer vs teflon washer
washer installed on fitting
detail of bonded washer

Next I had to wire the sensor to the ECU. It's a pretty straighforward affair, with a 12v switched, ground, and signal return wire. On this wiring harness, I've been rather anal about my wiring and connectors. I didn't want a mass of butt-spliced connectors in a nasty harness, and thankfully, the flex fuel sensor uses the same connector and terminals as the throttle position sensor. I had a few terminals left over, and was able to quickly make a harness for the flex fuel sensor.

My Megasquirt 2 ECU required a few mods in order to accept the signal from the sensor. These are outlined below, mostly just for my own reference, and for the benefit of any random google searchers who may come across the images.

The final step was to configure the software to accept the signal input. A couple clicks later, and I was reading a 1% ethanol mix. This seems reasonable to me, but I guess the only way to check is actually add ethanol to the tank and watch the sensor respond. Thankfully there are a handful of stations that sell corn squeezins within ten miles of me. 

There will be more pictures and words (you guys like those, right?) in the weeks to come. In the meantime enjoy this Volvo P1800 I saw the other day, and don't get eaten by tigers.

1 comment:

  1. Awesomely written and informative article! Thank you