O2 signal - backpressure compensation

Testing and development of Megasquirt 3

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O2 signal - backpressure compensation

Postby thedrew » Wed Oct 25, 2017 4:21 pm

I see an old thread in 2012 about this, but nothing since then.

For those of us wanting to monitor O2 before the turbo, this would save us buying an external unit to do the compensation for us.

Was wondering if this is planned or somehow managed already?
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Re: O2 signal - backpressure compensation

Postby racingmini_mtl » Wed Oct 25, 2017 5:28 pm

The O2 compensation has to be done by the WBO2 controller because that is dependent on the Nernst cell current inside the sensor. This is not visible externally so it cannot be done in the MS3.

So you need a controller that supports this. The MegaSpartan from 14point7 does support it and is designed for easy integration with the MS3. There are likely others but I'm not familiar with them.

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Re: O2 signal - backpressure compensation

Postby thedrew » Thu Oct 26, 2017 2:09 pm

thanks. I'll look into Alan's solution -- he says the backpressure stuff isn't done yet, but in a couple months the new firmware will be out.

The AEM 4-channel CANBUS unit uses the LSU 4.2 sensor. A rep said using the LSU 4.9 sensor is "on the horizon" -- whatever that means.
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Re: O2 signal - backpressure compensation

Postby chips60bug » Thu Oct 26, 2017 8:31 pm

thedrew wrote:thanks. I'll look into Alan's solution -- he says the backpressure stuff isn't done yet, but in a couple months the new firmware will be out.

The AEM 4-channel CANBUS unit uses the LSU 4.2 sensor. A rep said using the LSU 4.9 sensor is "on the horizon" -- whatever that means.

Have you heard from him on this recently?
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Re: O2 signal - backpressure compensation

Postby thedrew » Fri Oct 27, 2017 8:05 am

yeah, i emailed him about it this week and got this:
The pressure compensation feature is still being worked on, a new firmware will be released in about 2 months. The firmware is end user updateable.

I will carry and sell the pressure sensor once the new firmware is released.
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Re: O2 signal - backpressure compensation

Postby chips60bug » Fri Oct 27, 2017 8:11 am

Good to know. I have firmware in mine right now that is supposedly doing the comp stuff. I sent some datalogs to him early this week, hopefully he can do good things with what I gave him, cuz my car is done for the season, requiring some pretty major TLC.
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Re: O2 signal - backpressure compensation

Postby thedrew » Fri Oct 27, 2017 8:15 am

Yeah, I'm about ready to pull the trigger on the megaspartan -- my cars done till the spring, so I hope the firmware is done by then.

I can't decide if I want the 5 channel (to pick up the average) or is the 4 channel all I'll ever need.
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Re: O2 signal - backpressure compensation

Postby chips60bug » Fri Oct 27, 2017 9:26 am

I use the 4, with an outside 5th till i trust the device. The computer creates an average and uses it to tune your ve table with. Running a 5th will be difficult to do and not confuse the computer. I currently run my 5th as a generic sensor, i feed it direct to the IOX over serial, then i convert that signal to a 0-5v and use an ADC from the IOX to the MS3 as such. I then just input the Innovate calibration data and created a gauge. That way it doesn't have any affect on the tune. It responds later than the per cylinder devices do, so it definitely made tuning tricky back when i had it listed as a 5th ego.
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Re: O2 signal - backpressure compensation

Postby thedrew » Fri Oct 27, 2017 9:34 am

chips60bug wrote:I use the 4, with an outside 5th till i trust the device. The computer creates an average and uses it to tune your ve table with. Running a 5th will be difficult to do and not confuse the computer. I currently run my 5th as a generic sensor, i feed it direct to the IOX over serial, then i convert that signal to a 0-5v and use an ADC from the IOX to the MS3 as such. I then just input the Innovate calibration data and created a gauge. That way it doesn't have any affect on the tune. It responds later than the per cylinder devices do, so it definitely made tuning tricky back when i had it listed as a 5th ego.



good to know, thanks!
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