i have a ? about smog pump can you pass emissions with it out and is it really worth taking it out. i am also guessing it probably has something to do with emissions
The catalytic converters on the 5.0 Mustang were designed to use the extra air provided by the smog pump to complete the catalytic reaction. Without the smog pump, emissions go up and the cats will clog up and choke the engine.
Later model cars had cleaner running engines that did not require a smog pump. Trying to adapt the smog pumpless catalytic converters to a 5.0 Mustang will not work because the exhaust is too dirty. The cats will clog up and choke too.
Some review of how it works...
The Thermactor air pump (smog pump) supplies air to the heads or catalytic converters. This air helps burn the excess HC (hydrocarbons) and CO (carbon monoxide). The air supplied to the catalytic converters helps create the catalytic reaction that changes the HC & CO into CO2 and water vapor. Catalytic converters on 5.0 Mustangs are designed to use the extra air provided by the smog pump. Without the extra air, the catalytic converters will clog and fail.
The Thermactor air pump (smog pump) puts air into the heads when the engine is cold and then into the catalytic converters when it is warm. The Thermactor control valves serve to direct the flow. The first valve, TAB (Thermactor Air Bypass) or AM1 valve) either dumps air to the atmosphere or passes it on to the second valve. The second valve, TAD (Thermactor Air Diverter valve or AM2 valve) directs it to the heads or the catalytic converters. The air serves to help consume any unburned hydrocarbons by supplying extra oxygen to the catalytic process. The computer tells the Thermactor Air System to open the dump valve at WOT (wide open throttle) minimizing engine drag. The dump valve reduces the parasitic drag caused by the smog pump to about 2-4 HP at WOT.
Computer operation & control for the Thermactor Air System
Automobile computers use current sink technology. They do not source power to any relay, solenoid or actuator like the IAC, fuel pump relay, or fuel injectors. Instead the computer provides a ground path for the positive battery voltage to get back to the battery negative terminal. That flow of power from positive to negative is what provides the energy to make the IAC, fuel pump relay, or fuel injectors work. No ground provided by the computer, then the actuators and relays don't operate.
troubleshhooting
One side of the any relay/actuator/solenoid in the engine compartment will be connected to a red wire that has 12-14 volts anytime the ignition switch is in the run position. The other side will have 12-14 volts when the relay/actuator/solenoid isn't turned on. Once the computer turns on the clamp side, the voltage on the computer side of the wire will drop down to 1 volt or less.
In order to test the TAD/TAB solenoids, you need to ground the white/red wire on the TAB solenoid or the light green/black wire on the TAD solenoid.
To test the computer, you can use a test light across the TAB or TAD wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker.
what about a stock H-pipe with the 2 rear cats removed....are the front 2 going to plug up or are they different inside. I want to get a OR H pipe but if mine is prety much one now I will just leave it on my car and bypass all the smog crap (no e-test's here)