Denso MAP sensor testing
 

Does anyone have data on how the Denso MAP sensor works?

http://www.peachparts.com/shopforum/...1&d=1530730024

I can't find information on how this thing works but I was just playing around with it and discovered some values I would like to confirm.

Pin 1 - Purple stripe gray wire - Signal
Pin 2 - Brown - Ground
Pin 3 - Red stripe green wire - 5V

Atmospheric pressure = 3.755V
~25 in Hg vacuum = 0.700V
~20psi pressure = 4.90V

Positive correlation between pressure and voltage. As pressure goes up, voltage goes up and as pressure drops and vacuum is introduced, voltage goes down? Does this sound right and do my voltage ranges seem correct?

The sensing element in a MAP sensor is typically a piezoelectric strain gauge.

Is the 20psi pressure that you quote absolute, or above atmospheric?

Above atmospheric. I put a hose from my air compressor regulated to about 20 psi on the output and fed it to the MAP sensor to see what value I get from the voltmeter.

A factory manual might provide a pressure / voltage chart.

What car is this sensor from? I'm putting the # 011-542-06-17 in the post to help others searching for info.

This sensor specifically came from a 96 W202 C280, but it should be pretty universal from 1995-2000 in any of the cars.

My W124 manuals don't have any reference for this particular sensor (or at least I can't find it) and I don't have the later W202 manuals to look up. I was hoping someone could provide the pressure/voltage curve for me to compare against.

J5:

The 4.9V which you observed when pressurized is usually the max output, irrespective of the designed range (in atmospheres). The difference between a 1atm sensor and a 3atm sensor is in resolution. The max output of both is 4.9V.

If your pressure regulator is sensitive enough, try slowly increasing pressure until the 4.9V point is reached, then note the pressure at that voltage. You can then plot the three points, and check for linearity.

It's really odd that a normally aspirated engine's MAP sensor will read boost. In GM land, one must move to a 2 or 3 bar sensor if running boost.

At least on the 97 C 280 / E 320 / SL 320, they use Bosch ME 2.0 / 2.1 engine control. I'm pretty sure the MAP is only used for OBD diagnosis and / or maybe transmission control but don't quote me on that.

Pre 97ish had a hydraulic trans so trans control would not be possible on early cars.

Given the sensor is Denso ( Japan ) there has to be a turbo car out there that uses a similar sensor that you can compare pressure to voltage.

Found the values in TunerStudio, I didn't even need to do this work myself.

For anyone searching this topic in the future:

0V = -20 kPa
5V = 146.7 kPa

http://www.peachparts.com/shopforum/...1&d=1531203651

edit: just noticed units aren't kPa, but %. Not sure what that means, but the sensor is working with the Toyota Denso predefined values.