Whats this? - Ford Forums

89F150 · 03-08-2004, 01:41

Theres a 1/2 inch pipe that runs from behind the engine down around behind the first cat. Whats that for? I'll try and get photos if you don't understand me.

'92BigBronco · 03-10-2004, 16:20

That's for the smog pump. The purpose of the smog pump is to force more oxygen(from the outside air) into the exhaust system right before the catalytic converter. Doing so allows the converter to catalyze more of the unburned hydrocarbons by providing more oxygen for the process, thus reducing emissions.

Catalytic converters are not 100% efficient. If they were, the only thing coming out of the tail pipe would be pure water vapor and oxygen. Pumping air into it brings the efficiency up. The only other way to completely eliminate emissions, and the need for a catalytic converter for that matter, is to attain 100% combustion.....which isn't possible at this time because of the impurities and additives in gasoline along with limitations in current engine designs.

Hope this clears things up a bit.

Brian

89F150 · 03-10-2004, 23:57

Thanks Brian for the help. I was just wondering because that little pipe broke away from my exhaust the other day and it made it sound like crap.

'92BigBronco · 03-11-2004, 10:14

Yup, it will do that. If it broke off, you basically now have a nice big hole in your exhaust pipe. It'll hiss like nobody's business under acceleration.

89F150 · 03-11-2004, 22:32

Yeah it sounded like crap but its all fixed now.