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Discussion Starter · #1 · (Edited)
Thought that this was a interesting scope pattern with the AEM controller.
AEM_WB_controller.JPG

The square wave had me going there for a few minutes.

Warming up the engine
AEM_WB_controller_coldengine_warm_up.JPG

Then warm engine and goosing the throttle.
AEM_WB_bumping_the_throttle.JPG
EDIT: After looking at this I need to add more channels for clarity with what's going on.
Next time I'll also grab the TPS voltage to show the rate of throttle opening along with the MAF values.
 

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I used one of these on a MRS turbo project. They are pretty good, but I had to recalibrate it every once in a while and clean it quite often. I'm not quite sure what you're showing though. Also what program are you using to show the wave form?
 

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Discussion Starter · #3 ·
It's a screen capture from a modis.
Any idea whats causing the small square wave?
 

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Oh, wow that is a modis. I haven't used one of those since i was a mechanic. Quite a nice tool, and quite expensive if I remember. Wouldn't mind adding one of those to my tool kit :cool:

Well if I recall correctly the wideband sensor sent out a signal to the Aem controller that came with it. Then the controller turned this signal into a 0-5v signal for use with an aftermarket ecu of choice or just to view the out put signal to see what the lambada was.

I can imagine the sensor it's self emitting a small square wave almost like a regular 02 sensor. But the controller it is suppose to be hooked into, I think, would be outputting a sine wave 0-5v.

I can't really remember what the e- manage and profec e-01 I was using at the time showed.( This was a project back in '03 ) But if you are reading directly from the sensor without using the controller I could see you getting a small square wave i suppose.

Also there was an output from the controller that was suppose to be what a stock and standard o2 would send to cars original ecu so it throw and codes. If you were looing at this output as well it would probably be a small square wave.

Oh I just looked at the pics a little more and think all the other stuff I said is irrelevant .

I'm not a electrical engineer or anything, but I'm thinking at this point that maybe you have to much clarity on the signal. Maybe the way the controller works is just not so great so it's leaving some of the square in the wave. I imagine if it worked better you would just see a nice flowing line. Maybe it doesn't filter the original square as well as it should, or maybe the modis is just to good. But I bet if you stepped it back some it would look like a regular sine wave. All I know is ecu's read it fine, and that's fine with me :)
 

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Discussion Starter · #5 · (Edited)
Ok now I'm confused.
First I thought that by running the brown(analog -) spliced into
the black (ground) was the cause.

After cutting the splice I still got this waveform.
AEM_free_air_cal.JPG
As you can see the scope is averaging the voltage of the square wave.

Then I stepped it way back.
100V scale over a five second time frame.
The square wave can still be seen.
AEM_highscaling_long time_frame.JPG
 

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Well I'm not exactly sure. I never hooked one directly to a O-scope.
Maybe that is just how it outputs. I know the controller is suppose to put out a linear DC voltage, is this what a linear DC voltage signal looks like?
Maybe there is a little interference because they are grounded separately.
As I said I'm no E.E. I'm a wanna be M.E. who's just trying to be a R.E(thanks Da vinci)

Are you using the inline controller or the gauge type?

After calibrating it as long as it reads correctly and moves as it should (+/- V) when the throttle is applied then it should be fine.

Pop on a E.E forum and ask. I'm kind of interested now too. I could never find a pic of what a linear DC signal looks like or anyone else who has put an AEM controller directly to a o-scope
 
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