Can anyone tell mewhat this is and if I need it?
car is a 86 T/A 305 4bbl AC delete. smog delete.

 

It is the baro sensor. It measures ambient pressure - obviously, intake manifold vacuum is the difference between this and the MAP reading.

If you still have the ECM, you need it.

 

looks like it use to have something on the vacuum type fitting? maybe a filter, can it be tested to see if it is working?

 

It is the baro sensor. It did not have anything attached. There may at one time have been a foam filter of some sort inside the thing that looks like a hose would go there. It measures atmospheric pressure.

I know of no good way to test it.

 

The only way to test it is by monitoring the output voltage (0-5VDC) and a known pressure. I have pressure/output tables for MAP sensors, but unfortunately, not for a BARO sensor.

 

Thanks for the info! I had always assumed baro sensors were like map sensors (as regards the vacuum line).

For what it's worth, http://www.sunpro.com has a great deal in their garage sale link (under test & tune) for a sensor tester that can read MAP and MAF sensors. (It was replaced by Sunpro with a more advanced tester that reads even more sensors...)

 

Thanks for the information. I'm just trying to clean up under the hood, and get rid of unnecessary stuff like wiring for AC ans fuel injection which I don't have. So if I don't know what it is, this is a great place to find out before I make a bad mistake.