Just a couple of questions regarding the smog stuff on my 1983 Ford F150 (300 inline 6 cylinder). I have a four port Thermal Vacuum Switch (TVS). If I decide to unhook all my smog stuff (air pump, EGR valve, etc...), are there any of the vacuum lines that come from the TVS that I will need to leave connected? Also, does the TVS send info to the temp guage on the dash and if so, will this still work? If not, can I remove the TVS and plug the opening off that this screws into?
Lastly, does the system that operates the damper door in the breather operate differently from the smog stuff and will it continue to operate if I unhook the air pump and EGR valve?

 

Does the truck have a Microcomputer Control Unit? MCU?

If the truck has a MCU....

The MCU relies on the ported TVS for information on if the engine has come to operatiing temperature, or if the engine is still cold.

There are Four Vacuum switches on the rear of the truck hooked to the valve cover. The first one is the temp switch, that is hooked up to the ported TVS. The Second/third and Fourth are either the closed throttle, wide open throttle, or the Crowd #3. All these switches will have to work properly for the computer to run the engine right, and to adjust the fuel mixture on the carb accurately.

The MCU controls the following:

Fuel Mixture, via the Feedback solinoid and O2 sensor
Spark Retard, via the Spark Retard Solinoid
Thermactor System Via the Tab and Tad solinoids a air pump and catalitic converters
Charcoal Canister Purge via the Purge solinoid and the PCV valve.
Cold and Warm drivability (richens or leans mixture) via the ported TVS and another electical vaccume switch stated earlier.

You can remove the EGR and the Airpump (part of the thermactor system) but, It could cause some driveability problems (egr etc..) such as ping or predetonation on some system calibrations. Or it could cause the computer to be placed in limp home mode, etc... causing more fuel consumption, etc...

To safely remove the EGR and Airpump, and other smog devices like you are wanting, and to dispence with the possibility of driveability problems, you will need to exchange the computer and feedback carb, with those from a non feedback system.

You have to ask yourself the question. "Why am I removing the smog?" Is it because you want better performance? or because the stuff don't work anymore?

If it's because you want better performance or gas mileage, you could possibly make it worse by removing the components from the smog system. The earlier non computer models tend to get less gas mileage (15/18 Mpg) than the later carberated computerized models (19/21 MPG) on average.

If there is something wrong with the system, then it may be cheaper to fix the problem than to modify the system to an earlier calibration.

To answer your other questions, The TVS doesn't control your Dash guage on this year model, you have a seperate sending unit for that, but the computer does rely on it working as stated earlier.

The "damper door" is controled by manifold vacuum and seperate TVS switches located inside the aircleaner. It shouldn't be affected by removing the EGR or Airpump.

Hope all this helps you out.

 

Thanks for the info. Luckily, I do not have the computer controlled system. It is an earlier model with simple smog stuff.