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New wideband controller ALM compared to Innovate LM-2
http://forum.diyefi.org/viewtopic.php?f=14&t=1033
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Author:  Fred [ Mon Jan 30, 2012 9:20 am ]
Post subject:  Re: New wideband controller ALM compared to Innovate LM-2

I tweaked your post, I hope you don't mind. And I have some questions:

- Are the readings taken digitally with serial and/or I2C or from the analogue ports?
- Is the noise on the LC1 trace a result of the PWM heater wiring? And if not, what is it?
- Am I right that it looks like the LC1 is tracking the sensor pretty closely and that your one kind of "snaps" to the correct value?
- What would your unit look like when confronted with a fast moving smooth signal? Would it step through the wave form or would it track it?

LOL @ LC1 + Error8, that's terrible...

Thanks for this info!

Fred.

Author:  toalan [ Mon Jan 30, 2012 10:24 pm ]
Post subject:  Re: New wideband controller ALM compared to Innovate LM-2

Readings are taken from the linear analog output

Not sure where the noise is coming from, I was just after response time in that screen capture.

The snapping, I do not know if this is representative of how the gas is hitting the sensor. Generally I would prefer a smoother curve, I might put in some firmware filtration to smoothen the signal out. I am not happy with either my current curve or the LC1 curve, the readings should show slightly richer than 0.8 (lower voltage) then quickly recover to 0.8 lambda, the pressure of the gas hitting the sensor should cause the sensor to read a bit more rich. Both look like an overly dampened response to me.

I do not have any data backing up how my unit will behave with a fast moving but slow changing gas, I would expect the output to be smooth, but I can not simulate that and get clean scope traces on my bench.

Author:  HelmutVonAutobahn [ Mon Nov 30, 2015 10:37 am ]
Post subject:  Re: New wideband controller ALM compared to Innovate LM-2

Quote:
the readings should show slightly richer than 0.8 (lower voltage) then quickly recover to 0.8 lambda, the pressure of the gas hitting the sensor should cause the sensor to read a bit more rich. Both look like an overly dampened response to me.


Pardon the thread necromancy. But, that sounds exactly like the trace I got testing the new AEM gauge, in the "Widebands That You Would or Wouldn't Buy" thread. I hit a sensor, in free-air, with a shot of CO2. It "overshot" to about lambda 0.98 for about 10ms. Then it recovered to 1.00, over the next 10ms. You think that is from the pressure wave? I thought, maybe, shock-cooling of the element. Or, a combination of both.

Author:  toalan [ Sun Jan 17, 2016 2:15 am ]
Post subject:  Re: New wideband controller ALM compared to Innovate LM-2

The trace in question was My spartan 1 and the Innovate LC1. Neither use PID to control the sensor.

The AEM uses PID to control the sensor as it relies on the Bosch IC and the Bosch IC uses a classic PID approach to control the sensor.

In a PID system an over or under dampened response can be attributed to the PID control loop, it is hard to say if the response is reflective of the sensor response or due to the PID control or due to both.

Spartan 1 and the LC1, do not use a PID loop, so you can rule out PID as the culprit.

Author:  HelmutVonAutobahn [ Tue Jan 19, 2016 8:35 am ]
Post subject:  Re: New wideband controller ALM compared to Innovate LM-2

Hey Alan :)

if you check out at the pictures of the new AEM gauge PCB that I posted, there is no Bosch chip there. Just amps and switches. ( and a big inductor for the heater )

http://forum.diyefi.org/viewtopic.php?f=6&t=2267&start=140

The trace that I got out of it, hitting it w/ CO2, is on the next page. It doesn't appear to have the characteristic "rounding off / tapering" as it settles on its target value, like a PID. It does go slightly over-rich ( ~ lambda 0.98 ) for about 20ms.

With the dv/dt it shows, approaching its target value, that "dip" cant be a characteristic of a control PID. But, it could be the pressure sensitivity of the sensor, if there is a pressure wave? The spec shows about +1% dIp/Ip per psi. I guess 20ms isn't too hard to believe.

Or... it could be a quick temperature variation from the cold shot? Spec gives dIp/Ip = 4% / 100C

Or, some combination. Or something completely unrelated? You seemed to predict this behavior. So, I thought I'd get your take on it :)

I have seen a similar "dip" on an LC-1 running in "instant mode", with the same test. But, there was not nearly as much resolution, time-wise ( maybe 3 samples ). And, it was harder to pick it out of the noise. But, it's there.

I guess I could repeat the test with the sensor already saturated at lambda 1.0 and look for the reaction to the shot. But, then, I'd have to set it all up again :roll:

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