First off I have a electronic controlled carbureted 305 T-5 86 IROC. I first had 3 codes, 13,21,24,32. these were O2 sensor, throttle positioning sensor, VSS, and differential pressure sensor. I was told the VSS could be causing some of the other codes so I took another gauge cluster I have that came from an 86 TPI 305 car. I hooked it up, cleared the codes drove it down the road. the engine light came back on BUT when I checked the codes it only had 2 codes: 21- Throttle positioning sensor and 32 Differential pressure sensor. Now the question is this, I know the TPS is on the left side of the carb but I need to know where for sure the differential pressure sensor is. Is it the same as a map sensor? My repair manual shows a pic of a carb engine with a "Baro Sensor" mounted close to the brake booster and it shows another pic of a fuel injected engine with a MAP sensor mounted by the heater box on the firewall. Here's the kicker mine has both! They both have electrical connections going to them but the one by the booster has a vac line going to the back of the carb (like drawing under the hood shows) but the one by the heater box doesn't have a hose going to it and there's not one loose anywhere close either. Anyone have any ideas?

 

Yes, your 1986 system should have both a MAP and a BARO sensor.

The sensor with the vacuum line connected is the MAP (called a "Vacuum Sensor" in 1986). Its vacuum source line should be connected to the angled "N" port on the rear of the throttle body/base of the carb. The MAP should have a black, gray, and light green wire connected to it.

The BARO sensor will not have a hose connected, since it senses atmospheric (barometric) pressure, not manifold vacuum (or Manifold Absolute Pressure). The BARO should have a black, gray, and gray/red striped wire connected to it.


I have lots of ideas, but I'll spare you rather than bore you to tears with my musings.