hello so I just got a 1986 firebird v6 MPFI. I just replaced the EGR switch and as I finished a found a broken vacuum pipe. I found this diagram for the car and can see it goes to the Vac. Sw. what exactly is that? Any help is appreciated!

 

 

The vacuum switch , pictured in the above drawing as part of the "electronic vacuum regulator valve" but is in reality a physically separate component , is a confirmation to the ECM that the command to open the EGR valve has actually produced the intended result . The ECM commands the solenoid to open , putting vacuum on the EGR valve to open it . When that vacuum is applied , it also closes the vacuum switch "telling" the ECM that the vacuum was in fact applied to the EGR valve . The ECM will then look for a bump in the O2 sensor reading , confirming the EGR valve did actually physically open , and the happy emission control system doesn't throw an EGR code . Let the solenoid be commanded and the switch not close , or let the solenoid be commanded and the switch close but no bump in the O2 reading , and the unhappy system will throw the EGR code and put the check engine light on .

 

Ah ok cool. Could this possibly cause a lot of power loss from the engine?

 

Ok so I replaced most of the bad hoses. I’m trying to find the vacuum switch but I’m having a hard time locating it. It wouldn’t happen to be the MAP sensor would it?

 

The vacuum switch should be mounted to the same bracket with the EGR solenoid , and no that is not a MAP sensor . You said your car is a 1986 2.8 , that will be a MAF rather than a MAP setup . EGR valve problems will usually mess up your idle more so than causing a lot of power loss from the engine . If this is your goal , diagnosing why it's down on power , I'd suggest that after you finish making sure all of the vacuum hoses are good and doing all the normal tune up stuff to then do all the normal basic tests ; Hook a vacuum gauge up to it , do a compression test , check the fuel pressure , those kinds of things ...

 

That’s what I figured with the sensor. I looked on the bracket and i think I may have found it but I’m not entirely sure.

Is it the connector with the pink/black wire?

this is basically what I found when I first started repairing the vacuum system. Not sure where it goes. It connects to a T on the regulator.