Jurrel

Okay this is a 1984 Pontiac firebird. It's ran rough more or less since I got it 6 months ago. I have done a general tune up, but nothing has solves the rough running. I have noticed where the Baro sensor should be there is no sensor. The plug is there however. Should this car have one? how much would it cost for one? And most importantly what damage is it doing by not being there?

Thanks!

KED85

I have kinda same vehicle you do, but I am unaware of this item you speak of.
My 1985 Blazer is a 2BBL 2.8 Federal version.

Hit the yards & check the 2.8 FWD cars, too.
Same things.
To a point

Jurrel

Well I have the Pontiac service Manual for the 1984 Firebird, it mentions the Barometric Pressure sensor. I have no idea if they were used on Chevy Blazers, as it is a peice of smog/emissions equipment. Was hopeing other Carb'd V6'ers might reply if theirs came with the Baro sensor or not.

Jurrel

Yes I am replying to myself allready.

After sitting down and seeing nothing intresting on TV I have started to read the service manual from cover to cover. I finally found the section on the Baro in particular. That part is on all 2.8L V6 firebirds...except those sold in California..which mine was, so I guess I have answered my questions

Thanks ked for the attempt You always have good ideas at least.

KED85

Bump up your timing that CAN assist

KED85

Here's a road map that may assist also.
But yeah the FWD to a certain year are identical
COULD BE UP TO 1984 model years

82-T/A [Work]

I could be wrong, but from what I understand the barometric sensor is the temperature sensor on the air cleaner. It's part of the thermac system. The thermac system serves no purpose other than to help you warm up your car faster in cold starts.

The thermac is that valve at the end of the neck on the air cleaner. When closed, it pulls air from what would look like a dryer tube. The dryer tube usually connects to a series of tin-work that surrounds an exhaust manifold or y-pipe.

Since it pulls air through there, it sucks the air past the hot exhaust manifolds, heating the air, which is then pulled directly into the motor to heat it up quicker.

When the valve is opened, it pulls air regularly from the end of the air cleaner neck. Now, this thermac valve is controlled by vacuum. There is a constant positive vacuum on this line at all times. What shuts the vacuum on or off is a temperature sensitive plate that's usually riveted to, or bolted to the inside lower portion of the air cleaner housing.

In other cars, the thermac valve is controlled by a coolant temperature sensor on the intake manifold.

The Thermac also does provide some emissions control while the car is running too... in the case where it has the temperature valve on the air cleaner, if the air comming in is much cooler, it can pull hotter air through the thermac... thus, increasing the overall temperature of the exhaust. This is so that the exhasut can be converted better by the catalytic converter.

CC_HotRod

Are you talking about the sensor in the air cleaner that has 2 vacuum lines going to it?

82-T/A [Work]

Yep, that one. Is that one "technically" calle the barometric temperature sensor?

or no?

CC_HotRod

The chilton calls it a Temperature Sensor, but it does like you described above. Chilton calls the Air Cleaner a Thermostatic Air Cleaner (Thermac)

OPERATION: "All engines use the THERMAC system. This system is designed to warm the air entering the carburetor when underhood teperatures are low, and to maintain a controlled air temperature into the carburetor at all times. By allowing preheated air to enter the carburetor, the amount of time the choke is on is reduced, resulting in better fuel economy and lower emissions. Engine warm up time is also reduced. The THERMAC system is composed of the air cleaner body, a filter, sensor unit, vacuum diaphragm, damper door, and associated hoses and connections. Heat radiating from the exhaust manifold is trapped by a heat stove and is ducted to the air cleaner to supply heated air into the carburetor. A moveable door in the air cleaner case snorkel allows air to be drawn in from the heat stove (cold operation). The door position is controlled by a vacuum motor, which receives intake manifold vacuum as modulated by the temperature sensor. **A vacuum door which remains open will cause carburetor icing and poor cold driveability and a door which remains closed during normal engine operating temperatures can cause sluggishness, engine knocking and overheating."

Jurrel

That is the THERMAC not the Baro sensor, the Baro looks alot like your MAP sensor and is located on the passanger side of the firewall. It does not appear to ba apart of any california cars however.