FreeFuel ECU patch - a flex fuel implementation to Evo ECU
Newbie
Joined: Sep 2011
Posts: 29
Likes: 0
From: Bavaria
If using an external crystal with 16MHz or 20MHz you could easily add UART for debugging/monitoring, show all values on an LCD with fancy animations and control your espresso machine besides the simple signal conversion and still have to insert lots of NOPs/SLEEPs to burn CPU-cycles...
I mostly end up writing in assembler as I find interrupt programming more intuitive/easy to follow in assembly than in C, not to speak of even higher languages. Just initialize your interrupt vector table, activate interrupts and write your interrupt routines. Maybe push some registers onto the stack if needed by the main program flow and pop them after the ISR and thats it...
For code that directly drives the hardware I often find it harder to keep track of the abstracted code of higher level languages than tha actual (assembly) program flow how the CPU is processing it...
Besides: It improves assembly skills needed for ECU code dissecting and understanding
Last edited by r4p.t0x; Apr 29, 2015 at 07:09 AM.
Bryan,
I know this is an older question, but I think he means "digital" as in using a computer to count the frequency pulses from the GM sensor rather than the LM2917 chip and analog components in a more rudimentary setup. Both units will produce a voltage output like the ZT or any other type of sensor controller that has a 0v-5v analog output for ECU data-logging.
ast,
Hey ast, don't bash my 100K resistor.
j/k. The only reason for that is smoothing of the signal output to a nice steady voltage [when coupled to the LM2917's output in my configuration]. This is really coming along, though, and I like the fact that you and others are people making digital/computerized solutions--and that's where I wanted it to go, but I didn't feel the capabilities of some off-the-shelf proto boards were up to par.
I know this is an older question, but I think he means "digital" as in using a computer to count the frequency pulses from the GM sensor rather than the LM2917 chip and analog components in a more rudimentary setup. Both units will produce a voltage output like the ZT or any other type of sensor controller that has a 0v-5v analog output for ECU data-logging.
ast,
Hey ast, don't bash my 100K resistor.
j/k. The only reason for that is smoothing of the signal output to a nice steady voltage [when coupled to the LM2917's output in my configuration]. This is really coming along, though, and I like the fact that you and others are people making digital/computerized solutions--and that's where I wanted it to go, but I didn't feel the capabilities of some off-the-shelf proto boards were up to par.
I would test dry (50hz) and then with some 190-200 proof alcohol (155 hz) (lol) while it's connected to the ECU to get your floor and max values if you want a perfect cal. Or, just verify your tank with known gasoline or ethanol sources and go from there. You should be fine! This unit takes about a second or two to register a change in ethanol mix.
The LM2917 was designed for RPM circuits and if you build on a better power supply (mine is a little crude, but 100% functional), it will be rock solid.
Good luck!
I have not had issues on my test bench and I used various dirty voltage sources along with flimsy breadboarding and soldering. It's pretty simple and should work just fine. I think there are some already using it in the field and I have 100% faith in the circuit as it sits. I'm sure ast's new solution has more features, but this will get you going.
I would test dry (50hz) and then with some 190-200 proof alcohol (155 hz) (lol) while it's connected to the ECU to get your floor and max values if you want a perfect cal. Or, just verify your tank with known gasoline or ethanol sources and go from there. You should be fine! This unit takes about a second or two to register a change in ethanol mix.
The LM2917 was designed for RPM circuits and if you build on a better power supply (mine is a little crude, but 100% functional), it will be rock solid.
Good luck!
I would test dry (50hz) and then with some 190-200 proof alcohol (155 hz) (lol) while it's connected to the ECU to get your floor and max values if you want a perfect cal. Or, just verify your tank with known gasoline or ethanol sources and go from there. You should be fine! This unit takes about a second or two to register a change in ethanol mix.
The LM2917 was designed for RPM circuits and if you build on a better power supply (mine is a little crude, but 100% functional), it will be rock solid.
Good luck!
I've been using the LM2917N for 2 years with no issues. The circuit diagram I posted is solid and it is an easy build for anyone with basic soldering skills. All up cost including sensor is less than $200 for a working ECA that you can connect direct to the ECU.
Quick check did not reveal any memory area overlaps or changed position of parts where code jumps are inserted. So it's hard to say why it doesn't work.
You could try Donner's 3D SD ROM at http://www.petterimutteri.fi/ROMS/96536706/ although I'm not supporting it in any way but I have done the check for memory area overlaps earlier. Also there's no documentation available.
You could try Donner's 3D SD ROM at http://www.petterimutteri.fi/ROMS/96536706/ although I'm not supporting it in any way but I have done the check for memory area overlaps earlier. Also there's no documentation available.
After well over a year I have finally gotten around to installing my ethanol content sensor into my car along with the frequency to voltage converter box made following cdrinkh2o's diagram.
I am having an issue though. When I measure voltage at the input pin to the ecu from the converter box I get 1.92 volts, which is about right for the E10 fuel I am using. However, when I log mut 83, I read 1.09V (scaling of 5/255*x). I would maybe expect maybe a slight difference as the converter box is grounded at a different place to the ECU, but this is too much of a difference. Anyway, If I measure the voltage at the pin with my volt meter grounded at a few different places I still get 1.92 volts. Anyone have any suggestions?
EDIT: As far as I have read mut 83 is the raw input voltage to the ECU. Can someone confirm this?
I am having an issue though. When I measure voltage at the input pin to the ecu from the converter box I get 1.92 volts, which is about right for the E10 fuel I am using. However, when I log mut 83, I read 1.09V (scaling of 5/255*x). I would maybe expect maybe a slight difference as the converter box is grounded at a different place to the ECU, but this is too much of a difference. Anyway, If I measure the voltage at the pin with my volt meter grounded at a few different places I still get 1.92 volts. Anyone have any suggestions?
EDIT: As far as I have read mut 83 is the raw input voltage to the ECU. Can someone confirm this?
Last edited by wreckleford; Sep 22, 2015 at 05:32 PM.
bummer that the X guys seem to have this figure out. if we could do flex fuel, i'd have NO problem running e85 any time i got a chance.
right now i'm tired of having to drain fuel before events (i can never seem to time my empty tanks in time with track days).
right now i'm tired of having to drain fuel before events (i can never seem to time my empty tanks in time with track days).
The patch is working for others, but it's not available for the 9. My issue seems unique. If I flash my regular non flex fuel rom to my ECU I still get the voltage difference when logging MUT 83.
if i had any knowledge, i'd help. all i can do is sit here and hope someone gets it figured out LOL
And people laugh at me for going to a Haltech. At least with the Haltech I didn't have any of these issues just plug it in set the tables up add fuel and tune it. It sucks your having problems but this is why I did not want to go this route. Talk to Tscompusa I know he has done a bunch of these maybe he can answer your question.