whats a smog pump?
 

I really dont know what a smog pump is. I have a off road h pipe. should i take the smog pump out?? do i even have one??? 89 5.0 lx hatch maf. Also, has anyone tried enlarging the hole between your stock airbox and the fender???? thanks:)

I'm no emissions expert, but this is my understanding of a smog pump:

It basically just pumps fresh air into your exhaust pipe to help dilute the emissions that get measured on the other end. There's a couple of vacuum operated valves that have some sensors somewhere that control the amount of air pushed to the exhaust. I'm sure all the CA guys have a good handle on emissions.;) . Ask them for a better explaination.

It won't hurt anything if you leave it hooked to your offroad pipe. You can take it off or leave it on. Be sure to take your belt off and check that it turns freely by hand. Had a buddy replacing a harmonic balancer recently and when he had the belt off, he found that his smog pump was so bound up that it could barely be turned by hand.

The air pump is used to keep the cats at a good operating temp (to warm them up when you start your car, they work better the hotter they get). If you have no cats (offroad pipe), you don't need it.

From what understand, it is the opposite. The smog pump pumps exhaust FROM the H-pipe into the motor. Somehow the fumes are supposed to do some kind of black magic and allow it to burn off un-used fuel or something.

Anyway, you don't need it.....that's all that's important

929
I think the EGR valve is what allows exhaust gases back into the intake. On my car the EGR vlv was connected directly to #3 header tube.

the air pump pumps exhaust gas from the tubes on the back of your heads down into a valve, then into a tube right before your cats on the h-pipe. Its only mission in life is to get those cats hot

The EGR valve introduces exhaust gas into the intake manifold to reduce oxides of nitrogen (NOx) by reducing peak cylinder temperature and pressure. Unfortunately, high cylinder pressure equals power.

Ah yes, as memory serves me.....you are correct.

Yeah, see, at least I got the theory right.:D

Here's what I've always understood the smog pump to do. It pumps fresh air into the hot exhaust which adds some additional oxygen molecules to the carbon mon-oxide resulting in more carbon di-oxide.

There were smog pumps long before Cats, so I'm sure they are not for heating them up.

You remove the pump, you get some more power and some more pollution...everything's a trade off.

I think I can find it in my heart to cope with the additional pollution....;)

Well, then you would be wrong.

The smog pump is nothing more than an air pump. It's original purpose was to send fresh air into the exhaust to dilute the emissions, but with the advent of catalytic convertors nearly 30 years ago, their purpose changed. Their purpose is to improve the efficiency of the cats, and, as mentioned, to help them warm up faster. In fact, they play such an important role now, that if you remove the pump without removing the cats, you will clog up your exhaust.

Take care,
~Chris