Measuring AFR

[WB9YZU]

Tom:
http://www.aces.edu/~parmega/efi/temp/wb/guide.html

-Ron

 

[old_man]

Thanks for the link. I will be designing my own setup to use an Arduino and do some fancy graphics on a colored LCD screen, but it never hurts to see how someone else dealt with the design issues.

 

[WB9YZU]

Sounds cool Tom, looking forward to seeing what you come up with

-Ron

 

[JeepBTDT]

Other Generalities-
Best hp afr 12.5-12.8:1
Best torque afr 13.1-13.2:1
Boosted 11.5:1 to 12.0:1.
This is just a basic tuning guide. Some Engines like a little more or less fuel due to many reasons... Cams, heads, pistons, turbo, supercnarger, and fuel used.

 

[JeepBTDT]

Voltage--AFR relationship

 

[JeepBTDT]

double post.
http://cherrypicker.tripod.com/id12.html

 

[old_man]

Thanks for the link. Designing a controller for a UEGO wideband is not a trivial task. You actually don't measure the output of the sensor directly, but the voltage that is required to control the pump cell to keep the sensor balanced. A PID controller is normally used due to the accuracy and dynamic needs of the control.

I am working on the electronics to actually drive the cell, and the code for the Arduino to control the hardware and display the results. I am tinkering with the idea of using an output from the throttle position sensor along with the UEGO results and feeding the signal back into the Renix MAP circuit to cause an automatic adjustment (tweak).

 

[Talyn]

I am tinkering with the idea of using an output from the throttle position sensor along with the UEGO results and feeding the signal back into the Renix MAP circuit to cause an automatic adjustment (tweak).

You might also want to take in an RPM signal for that. All the map adjusters I have seen that have multiple points use RPM + map/tps. It also wouldn't be a bad idea for it to store the modifications in a table so the changes wouldn't be so abrupt. Or.. make a table your self and have the Arduino modify as needed. This would be a neat project.

 

[old_man]

Careful this is a slippery slope. If I add tach, I might as well just roll the whole thing.:laugh:

 

[sidewaysstarion]

Will you have enough speed with an arduino to measure all of those parameters and output the correct voltage in a timely manner?

 

[old_man]

I could easily do real time control, but I intend to let the ECU do the heavy lifting, and only have the Arduino keep it in the range the ECU can handle.

I could easily have the Arduino custom re-map the curves from the MAP sensor in real time rather than just shift them up and down overall.

If I was going to do anything else, I would grab the CPS signal and use some smarts to vary the timing to better deliver power when I want it. No need for a high altitude CPS when you could dial the timing.

 

[Talyn]

Will you have enough speed with an arduino to measure all of those parameters and output the correct voltage in a timely manner?

There is a guy on JeepStrokers that I believe is using an Ardunio for engine control.

If I was going to do anything else, I would grab the CPS signal and use some smarts to vary the timing to better deliver power when I want it. No need for a high altitude CPS when you could dial the timing.

How would you implement this?