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Hi, i'm fitting a digital air fuel controller, as some of you know.

At the moment, i'm doing some debuggin in regards to what makes my output signal from my controller different to the original map output signal, as the ecu does not like it.

I'm after anyones personal accounts inregards to what the signal's wave form should look like on an oscilloscope, between the maps output signal and ground.

My brother and i hooked up our oscilloscope to the output and ground with the map sensor's original signal, and with my controllers output signal.

We found both to be a sine wave form, both oscillating positive and negative at a high frequency, with frequency decreasing and amplitude increasing with throttle (ie: increase in load and decrease in vaccuum). the only difference was that the frequency of the controller's output was of a lower frequency, and we believe that was due to the controller having a max of 22Hz processing ability (which included it trying ot keep up with the signals wave form and opening up tabled stored values in its other IC's).

We believe that the controller can not keep up with the frequency of the map sensor, and hence it comes out at a lower frequency that the ecu doesn't like (and hence the engine light comes on and the car goes into a safe mode).

This sine wave form is typical (from my research) of that of a digital map sensor, mainly found on fords. My controller would work fine on an analogue map sensor with a voltage that just goes up and down according to throttle and does not oscillate.

What kind of wave forms do you get on your 5sfe map sensor? does anyone know conclusively if its meant to be digital or analogue? My controller is guaranteed to work on MAF, but says it also works on map. assuming it only works for analogue.
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1990 Celica GTS
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You've got a lot more info then we do. Don't think many know how to use an oscilloscope or even own one.
I'll say your MAP sensor is the same as everyone else. So whatever you got is what we got too.
 
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