FreeFuel ECU patch - a flex fuel implementation to Evo ECU
Dec 23, 2012, 05:17 PM
#47
Are you testing any software or are you just installing the flex fuel sensor/ECA hardware. If you're working with some flex fuel software what ROM are you on and would you be able to share any info or is it super secret?
Dec 30, 2012, 02:07 PM
#50
Happy almost New Years.
I'm working on a no frills simple HZ to DC converter that has the least amount of components for failure. Also, I want it to be CHEAP. I've been doing some research and after building my JAW 1.04B after almost 4 years, I gained some motivation.
I chose the LM2917-8 and an LM317 as a voltage regulator. I'm no EE by any means, and I don't have a real oscilloscope, but I came up with this based on posted calculations, specs, forum results, and a crude spreadsheet. Call me a Reverse EE ha.
I have 10 pcs. of the LM2917-8 on order ETA a day or three and the "new" flexfuel (previous post) sensor is at the UPS hub waiting for me. I'll mock this up with my own power supply and may build a 555-driven astable frequency generator to "tune" the circuit or see if it is doable (it should be fine). I may just drive the FF sensor on the bench too.
Capacitances and resistances may be off by 10% or so until this is tested. Feel free to breadboard it up if you have the parts and are bored like me over the holidays. The voltage regulation part may not be necessary or maybe the voltage can even be stepped down a hair to fight dropout but this will not supply 12v to the sensor (again may not be an issue as people have driven it dry on the bench at 9v at gotten a HZ output) and create more heat on the regulator.
From what I see on the roms, lower floor and upper ceilings can be adjusted (in case output may range from say 1.4V-4.4V) so this may still work. The design should also be nice and linear.
...or...I'll just buy a ZT gauge haha (but after I test this). Any input from skilled EE's would be appreciated.
I'm working on a no frills simple HZ to DC converter that has the least amount of components for failure. Also, I want it to be CHEAP. I've been doing some research and after building my JAW 1.04B after almost 4 years, I gained some motivation.
I chose the LM2917-8 and an LM317 as a voltage regulator. I'm no EE by any means, and I don't have a real oscilloscope, but I came up with this based on posted calculations, specs, forum results, and a crude spreadsheet. Call me a Reverse EE ha.
I have 10 pcs. of the LM2917-8 on order ETA a day or three and the "new" flexfuel (previous post) sensor is at the UPS hub waiting for me. I'll mock this up with my own power supply and may build a 555-driven astable frequency generator to "tune" the circuit or see if it is doable (it should be fine). I may just drive the FF sensor on the bench too.
Capacitances and resistances may be off by 10% or so until this is tested. Feel free to breadboard it up if you have the parts and are bored like me over the holidays. The voltage regulation part may not be necessary or maybe the voltage can even be stepped down a hair to fight dropout but this will not supply 12v to the sensor (again may not be an issue as people have driven it dry on the bench at 9v at gotten a HZ output) and create more heat on the regulator.
From what I see on the roms, lower floor and upper ceilings can be adjusted (in case output may range from say 1.4V-4.4V) so this may still work. The design should also be nice and linear.
...or...I'll just buy a ZT gauge haha (but after I test this). Any input from skilled EE's would be appreciated.
Dec 30, 2012, 04:54 PM
#51
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Yikes!!!! That's a lot more motivation than I. I don't know that would not want to be able to see what the sensor is seeing. Its helpful to know the the ecu is interpreting the same values of if there is an issue.
Dec 30, 2012, 06:33 PM
#52
Thats where logging will come in handy...
Then we can think about gauges, blinking lights, you know and such. But I wanted to keep the proto-parts under like 30 bucks and I have A LOT of passive components laying around. Like bez (one of the early guys who navigated the EVO's ecu code) said years ago, it's "so my brain won't die."
Then we can think about gauges, blinking lights, you know and such. But I wanted to keep the proto-parts under like 30 bucks and I have A LOT of passive components laying around. Like bez (one of the early guys who navigated the EVO's ecu code) said years ago, it's "so my brain won't die."
Dec 31, 2012, 09:18 AM
#53
Newbie
Thread Starter
I also experimented with LM2917 based converter some time ago. My schematic did work but it was not completely linear and it's kind of hard to get good output voltage range as there's the 50 Hz offset in the sensor. Also the output stability is a compromise. More filtering offers stable output but slows it down and vice versa. That's the nature of the analog circuit, it's not perfect. However in my opinion it should still be good enough for most applications when properly tuned.
I tried to tune my circuit so that the accuracy and response speed should be acceptable for most cases. Here's the circuit I experimented with. I might still have my measurement results for this circuit somewhere on paper. If I find those I'll post them. I did use square wave from a function generator to simulate sensor output, oscilloscope to verify the frequency and output stability and a high accuracy benchtop voltage meter to measure the output voltage.
I know that Donner is working with the new sensor but it's up to him if he wants to share his findings with us or not. Most important things to verify are the pinout and is the output the same and if not what's the difference?
I tried to tune my circuit so that the accuracy and response speed should be acceptable for most cases. Here's the circuit I experimented with. I might still have my measurement results for this circuit somewhere on paper. If I find those I'll post them. I did use square wave from a function generator to simulate sensor output, oscilloscope to verify the frequency and output stability and a high accuracy benchtop voltage meter to measure the output voltage.
I know that Donner is working with the new sensor but it's up to him if he wants to share his findings with us or not. Most important things to verify are the pinout and is the output the same and if not what's the difference?
Last edited by ast; Dec 31, 2012 at 10:11 AM.
Dec 31, 2012, 10:19 PM
#54
ast, thanks for the input. the Vout of a 2917 is proportional to the Vin which makes it need a regulator at the least-based on the equations in the manual. It may just be an old design.
The lm331 on the other hand does not care about Vin and seems to be a newer chip. A reg is still a great idea anyways. I have that chip on order too and without straying from too many passive components in the technical example in the manual, I can get a pretty linear output (on paper) from the stock equation almost exactly as the above chip. I dunno, we'll see. I pick up an old o-scope and function generator tomorrow for my idea of having a good time.
I do wish someone has some good testing with the rom and off the shelf stuff to see how happy they are. Then I can motivate myself to patch the 9417 SD rom (man I HATE hunting through megs of code manually finding similarities and then compiling and re-checking/at least most areas are found now and I marked that stuff a while ago...I think...)
The lm331 on the other hand does not care about Vin and seems to be a newer chip. A reg is still a great idea anyways. I have that chip on order too and without straying from too many passive components in the technical example in the manual, I can get a pretty linear output (on paper) from the stock equation almost exactly as the above chip. I dunno, we'll see. I pick up an old o-scope and function generator tomorrow for my idea of having a good time.
I do wish someone has some good testing with the rom and off the shelf stuff to see how happy they are. Then I can motivate myself to patch the 9417 SD rom (man I HATE hunting through megs of code manually finding similarities and then compiling and re-checking/at least most areas are found now and I marked that stuff a while ago...I think...)
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pqek666 (Jul 30, 2023)
Jan 1, 2013, 02:46 AM
#55
Newbie
Thread Starter
LM2917 has built in 7.56V Zener diode. With series resistor R1 in my schematic it acts as a voltage regulator. Temperature has some effect on the Zener but that's also true for most external regulators. This is one of the reasons why a microcontroller with good external DA converter and good voltage reference would be best for the application.
Last edited by ast; Jan 1, 2013 at 02:52 AM.
Jan 2, 2013, 11:14 AM
#57
Newbie
Thread Starter
That's very good, finally we'll have information about the new sensor.
I have found with the older sensor that it's enough to have fuel in the sensor to measure quite accurately, it doesn't have to flow constantly. So with relatively small amount of fuels you should be able to measure both gasoline and E85 Hz.
I don't remember is older sensor output is push-pull or open drain type. You may need to add pull-up ressitor to output pin.
I have found with the older sensor that it's enough to have fuel in the sensor to measure quite accurately, it doesn't have to flow constantly. So with relatively small amount of fuels you should be able to measure both gasoline and E85 Hz.
I don't remember is older sensor output is push-pull or open drain type. You may need to add pull-up ressitor to output pin.
Jan 2, 2013, 11:22 AM
#58
Newbie
Thread Starter
FreeFuel v1.1 patch with boost interpolation is out!
Check the first posts for information and files. New zip archives also contain the old v1.0 files if somebody needs them.
Testing the boost control has been very limited as I don't use ECU boost and my car is standing in the garage over winter. All I can say that code seems to work in simulator when I stepped it through and also in the ECU by logging RAM debug variables. But I was not able to drive the car so it was just testing stationary with engine running. In TephraMod V7 the boost is gear based so I was not able to verify that it works properly at speed. So be careful and don't go to full boost immediately!
I wish everyone a Happy New Year!
Check the first posts for information and files. New zip archives also contain the old v1.0 files if somebody needs them.
Testing the boost control has been very limited as I don't use ECU boost and my car is standing in the garage over winter. All I can say that code seems to work in simulator when I stepped it through and also in the ECU by logging RAM debug variables. But I was not able to drive the car so it was just testing stationary with engine running. In TephraMod V7 the boost is gear based so I was not able to verify that it works properly at speed. So be careful and don't go to full boost immediately!
I wish everyone a Happy New Year!
Jan 2, 2013, 09:31 PM
#59
Badass ast on the boost interpolation.
Ok. Don't judge my o-scope. I bought is for 25 bucks yesterday with a function generator and a new probe from Fry's off of craigslist. It's vintage. I'm just learning now and you don't start out with a Ferrari. Just saying.
New sensor and pigtail. Part numbers are in my previous post. Seems to be made by Continental for GM. VCC, GND, and, VOUT are labeled on the casing too!:
Edit: See attachments
Quick and dirty test:
12V DC Power supply (3A/12.3V out)
NTE 6V regulator (about 6.03V out)
All grounds tied.
10K Pull-Up resistor.
1x probe setting
2V/Div setting.
5ms/Div setting.
Trigger functioning thank god.
New, dry, and capped flexfuel sensor. Room temperature.
Looks like a near perfect 50HZ! Dont judge:
Edit: See attachments
This flexfuel sensor *should be a fine replacement for the older units. I will get a syringe and inject fuel into it tomorrow or so and try to keep it controlled and safe for pump 93 and then pump e85 and will list the gas station too using two new jugs. This way people can be confident with buying this thing as a cheaper replacement with their ZT or other units.
I'm still waiting for my IC's but have modeled everthing in LTSpice and have added an active TL082 filter with and passive filter after it (5 bucks in parts lol). about 0.5-0.6s response time. It may be okay, but the models are near perfect linear from 1.6v-4.8v (12.5HZ steps siumlated) and .004v ripple at 50HZ exponentially getting smaller as HZ increase. We'll see if it's usable and works in real life that way or close. Everyone else, by a ZT guage or equiv and sensor lol.
Ok. Don't judge my o-scope. I bought is for 25 bucks yesterday with a function generator and a new probe from Fry's off of craigslist. It's vintage. I'm just learning now and you don't start out with a Ferrari. Just saying.
New sensor and pigtail. Part numbers are in my previous post. Seems to be made by Continental for GM. VCC, GND, and, VOUT are labeled on the casing too!:
Edit: See attachments
Quick and dirty test:
12V DC Power supply (3A/12.3V out)
NTE 6V regulator (about 6.03V out)
All grounds tied.
10K Pull-Up resistor.
1x probe setting
2V/Div setting.
5ms/Div setting.
Trigger functioning thank god.
New, dry, and capped flexfuel sensor. Room temperature.
Looks like a near perfect 50HZ! Dont judge:
Edit: See attachments
This flexfuel sensor *should be a fine replacement for the older units. I will get a syringe and inject fuel into it tomorrow or so and try to keep it controlled and safe for pump 93 and then pump e85 and will list the gas station too using two new jugs. This way people can be confident with buying this thing as a cheaper replacement with their ZT or other units.
I'm still waiting for my IC's but have modeled everthing in LTSpice and have added an active TL082 filter with and passive filter after it (5 bucks in parts lol). about 0.5-0.6s response time. It may be okay, but the models are near perfect linear from 1.6v-4.8v (12.5HZ steps siumlated) and .004v ripple at 50HZ exponentially getting smaller as HZ increase. We'll see if it's usable and works in real life that way or close. Everyone else, by a ZT guage or equiv and sensor lol.
Last edited by evoredy; Jul 24, 2016 at 07:53 PM.
Jan 3, 2013, 01:17 AM
#60
Newbie
Thread Starter
Thank's, very good information. Waiting for the results with fuel.
Do you have a close-up picture of the sensor connector without the harness attached? With the old sensor I used a universal 3-pin connector that I can get locally. It required just minor cut to fit the keying used in sensor, otherwise it did seal and fit perfectly.
One thing to note is that at least the old sensor was transmitting fuel temperature by varying pulse width. Pulse width also affects the analog circuit a bit as there might not be enough pulse width to charge capacitors at very low fuel temp. So if you can adjust pulse-width in your function generator, test with different widths. If I remember the pulse width range for the old sensor was 1 ms - 5 ms.
Do you have a close-up picture of the sensor connector without the harness attached? With the old sensor I used a universal 3-pin connector that I can get locally. It required just minor cut to fit the keying used in sensor, otherwise it did seal and fit perfectly.
One thing to note is that at least the old sensor was transmitting fuel temperature by varying pulse width. Pulse width also affects the analog circuit a bit as there might not be enough pulse width to charge capacitors at very low fuel temp. So if you can adjust pulse-width in your function generator, test with different widths. If I remember the pulse width range for the old sensor was 1 ms - 5 ms.
Last edited by ast; Jan 3, 2013 at 01:20 AM.