MAP Sensor Issue

[MCE7]

First, I would like to give a big thank you to all the posters on this forum. I have been lurking here for the last three months every since acquiring my 2004 sport. I have been able to solve many problems and improve the drivability just by doing a simple search and learning what others have done.

Now my problem.
I have been chasing a drivability issue and determined I likely have glogged catalytic converters. My secondary O2 sensor voltages bounce all over and my cat inlet temps are too high. But, before I replace my cats I am trying to determine why they clogged.

I believe the issue is with my MAP sensor. When connecting a vacuum gauge to the MAP sensor and using a OBD scanner, the vacuum gauge will show 17 inHg and the Scanner live data will show 12inHg at idle. When I increase the RPM to 2000 the vacuum gauge will read roughly 20 inches while the scanner reading increases to 9 inches.

Seems like the voltage supply and sensor wires might be reversed, but I checked it against the wiring diagram and all seems ok. I can't say for sure but it looks like the PO may have replaced the MAP sensor.

Any help is greatly appreciated.

 

[Kid Mechanic]

Disconnect the exhaust and run your tests again to get more data points. That way you can eliminate the “possibility” it’s the cats and get solid confirmation one way our the other and then go from there with more info.

 

[pagrey]

The factory service manual says the map sensor varies from 0.5 V to 4.5 V which corresponds to a pressure swing of 0-15 psi. The scanner you are using probably just doesn't know what it's looking at so it gives you values with units of inches of mercury. I don't know for sure but that's probably why the numbers don't make sense.