sensor signal conversion, any electronics gurus?

merkzu · Apr 2, 2007, 02:53 PM

GM makes a fuel composition sensor that sits along the fuel line and detects the ethanol content of the fuel. It outputs a 5V square wave at 50-150Hz relative to the ethanol content. 50Hz = 0%, 150Hz = 100%, etc. The AEM EMS has 0-5V inputs and a user definable fuel trim table. It would be pretty easy to have the EMS use the input from the sensor to automatically adjust fuel for E70-E85 if the sensor output could be converted to 0-5V. Then you could safely buy E85 out of the pump all year long making great power without worrying about your AFR going rich or lean on different blends.

Anyone know a shop that could make a converter? Would obviously have inputs for 12V & signal in, and outputs for signal out and ground.

merkzu · Apr 3, 2007, 01:03 PM

Well I found a huge step in the right direction.. they actually make frequency to voltage converters. Duh right?

http://pdf1.alldatasheet.com/datashe...SC/LM2907.html
http://pdf1.alldatasheet.com/datashe...A/TA8029S.html

Getting closer..

KevinD · Apr 3, 2007, 02:55 PM

yup frequency to voltage converter and then likely some voltage bias to make the 50hz = 0v. there are circuit diagrams all over the interweb for them. and when i do custom one off jobs like that, i always just request a "sample" chip and its free

edit* i'm not a electrical engineer though... and only a few of the circuits i make actually work. i've worked with the frequency to voltage ICs though in both traction control system i made, and a LED tachometer.

MalibuJack · Apr 3, 2007, 03:21 PM

http://www.aktivematrix.com/forum/viewtopic.php?t=166

This might be of interest to you.. Its a discussion on how to integrate the GM Fuel composition sensor with the mitsubishi ECU..

I've been researching this for quite some time.

MalibuJack · Apr 3, 2007, 03:23 PM

BTW, the GM Fuel composition sensor outputs a frequency for Ethanol concentration and also pulsewidth for fuel temp.. Just some additional information for you to chew on.

merkzu · Apr 3, 2007, 05:03 PM

cool, I'll join you over there. great to hear people are working on making this happen with the stock ecu, I was just going to dish out the cash for an AEM.. now I'll hold off on that

blkdinan · Oct 16, 2007, 09:55 PM

A microcontroller would be your best bet. It would give you the ability to write a simple program to achieve this goal. The company that set my car up does a lot of electronics engineering. I can run it by then and see what they think. If your willing to spend the money I’m sure the will develop it for you.

merkzu · Oct 16, 2007, 10:00 PM

Thanks, I already found a shop to design and create the components, have had it in the car for a while as just a gauge - works great

blkdinan · Oct 16, 2007, 11:38 PM

lemmonhead · Nov 1, 2007, 11:53 AM

huh didn't know those content sensors exist. As an electrical engineer I can whipe up a circuit in lickady split. This would make a sweet meth/water injection redundency fail safe system... fun fun