do i need a smog pump for my cats to work?

on my car and all other foxbodys for that matter if you have cats you need a smog pump right? what if you run cats and no smog pump? what happens?

and why dont newer stangs run smog pumps? are the cats different?
 
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sure you can run w/o smog pump and with cats, but i would bet the cats dont last as long or work as effectively. do you have stock H-pipe and cats?

good luck.
 
Today's fuel injection systems, chamber design/fuel-air mixing, and ecu's do a much better job of delivering an even cleaner mixture to the cats - so they don't have to work as hard as they used to.

Many people post and indicate that their cats clog more quickly without the air pump -- don't know how scientific that is, but it seems to be true.
 
intrcptrstng said:
Damn, this is like the 5th post about smog pumps/cats i have read tonight. Weird.
most of the country is frozen (not me - it was 70* and sunny today!). i think people are bored and doing some winter projects. :)
 
Hydrocarbon said:
I believe the main reason the smog pump was used, was to help the cats with the rich mixture during warm up, which was when most vehicles failed testing.
not sure about things in Medford, but testing is generally not done on anything but a hot motor. the smog pump sends air to the exhaust upstream of the cats during warm up, as i recall.
 
Hydrocarbon said:
Actually I was referring to tests the EPA made Ford do during engine development.
ahhhh-so. i did not read enough into what you wrote. my bad. :)

with your username, i expect excellence from you, especially on emissons threads. :cheers:
 
The cats aren't hot enough during initial warm up to help as they don't light off - that's why the air pump output is shifted to the heads on cold starts - so the cold air from it doesn't slow down cat warm up and light off. What helped control emissions to lower levels immensely during cold start up was heated O2 sensors. Instead of the 90-120 seconds needed to get the non-heated ones to operating temp (they have to get to 570F before they generate a stable signal), the heated O2's can be ready to go in 15-30 seconds, allowing the car to go into closed loop MUCH sooner on cold starts. Not only improved drivability, but allowed for better mixture control when cold - until the cats get hot enough to help. Air pump output gets switched to the cats once they're hot enough to light off.
 
Mr. Probst says:

The extra air from the Thermactor (smog pump) helps burn leftover HC and CO from the fuel-air mixture. The hot exhaust gasses resulting from the burning fuel-air mixtures in the exhaust manifolds help to heat the cats quicker.
 
They certainly do - and the reason the gases are still oxidizing (exothermic) in that part of the system (the cat) is because the air was injected at the back of the head when the engine was cold. Once the cats are warm enough to operate, the (cold) air is shifted from the head to be injected directly into the cat where the precious metals on the cat's ceramic matrix catalyze the very same reaction -which begins to take place in the cat, and continue oxidizing downstream of the cat.
 
Hydrocarbon said:
Mr. Probst says:

The extra air from the Thermactor (smog pump) helps burn leftover HC and CO from the fuel-air mixture. The hot exhaust gasses resulting from the burning fuel-air mixtures in the exhaust manifolds help to heat the cats quicker.
Also in addition, to deleting the thermactor, you continue to heat the cats up without the addition of the cooler air from the pump near closed loop. So while you drive around with no thermactor, you are actually defeating full-efficiency of the converters and they have been tested to run much hotter than designed to. This extra heat (and we are talking about a definite measureable amount) is what casues premature failure.

If you want to take it further the air pump moves oxygen of course. So one of the problems with vehicles equipped with a downstream O2 sensor (post converter) is that it will not read the extra oxygen that the computer automatically takes into account when figuring how much fuel to send for the correct stoich. air/fuel ratio. So the oxygen sensor doesn't see this and in turn tells the computer that the exhaust is either too rich and the engine needs to run leaner, or in reference to the upstream O2 sensor (which it relates to for cat. converter efficiency), it relates it as just that - a defective converter.