Smog pump / air pump

The smog pump (air pump) injects fresh air into the exhaust stream so there is a combustable mixture that enters the CAT, which heats up and burns the remaining fuel so that result is cleaner exhaust.

The exhaust stream contains unburnt fuel. The CAT burns this fuel through a combustion process, but combustion requires three things, air, fuel, and heat. The fuel is the remaining unburnt gas. The heat is the CAT itself. The air is injected by the smog pump.

So, yes, the smog pump is required.

As I recall, you are in California. CA smog rules *require* all of the factory emissions components, and if any of the ocmponents is missing, you automatically fail the smog insepection. It is entirely possible to have a vehicle that is modified and emits clean air, but if the smog equipment is missing, the car will fail. In order to remove smog equipment, you have to replace the system with a CARB (Calif. Air Resources Board) approved system.

We also talked the other day about your R12 air conditioning system. You will not be able to install a new R12 system, or rebild the missing parts of the R12 system you already have. You are forced to install an R134a system, and this can turn out to be an expensive proposition.

Thanks for the input. But I can get the ac system recharged with r12 for $150.00. Doe's that sound about right to you? Thanks Jamie

Does is not a contraction, you do not need the apostrophy.

Yes, $150 sounds reasonable for charging a system.

It does not really matter how much it costs to charge the system though, if you take the smog pump off. Without the smog pump, you can not drive the truck, and the AC won't help much when it is parked in the driveway. Allow me to restatet that, you can drive the truck okay, but you can not get the license tags renewed so that you can drive it on the street.

No combustion takes place in the catalytic converter. It is a chemical reaction. It is an exothermic reaction which is why the cat gets hotter - especially with an over rich mixture - but there's no fire.

Supposedly the air injected into the exhaust stream in the upper exhaust manifold or exhaust port is to allow combustion to continue into the manifolds. Since emissions tests measure the ratio of pollutants to air rather than the total amount of pollution, I figure all air injection really does is put clean air in the exhaust - which makes it register cleaner on a sniffer test.

Will it pass a sniffer test with the pump removed? If the engine is in good condition and the catalytic converter is nice and hot, probably.

Will it be legal? Technically, no. Depends on your state whether you can get away with it. In my area, there's no sniffer tests but functioning emission control equipment is part of our yearly state safety inspection. In a neighboring state, cars have to pass a sniffer test but that's all. You'd probably be okay there.

In California, forget it.

But why? Wasn't a truck like yours made with both smog pump and AC compressor? Go raid a junk yard and get the right parts.

You didn't mention the year or model - if it's OBD2 then who knows what will happen.

There is no combustion per se, but the CAT needs fresh air to work its magic on the exhaust. If all the CAT needed was heat, they would not be inclined to inject fresh air. The fresh air, remaining fuel, and heat all converge in the CAT to finish burning the remaining fuel.

If your theory of why they inject fresh air were true, they could inject the fresh air at any point in the exhaust system. The put it where it will combine with the fuel that is later exposed to heat and a chemical layer inside the CAT, where the NO is stripped out of the molecules and the unburnt gasoline is burned.

They do put clean air into the exhaust, and the exhaust then reads cleaner on the sniffer test, but the clean air they inject is doing more than diluting the crap that is in the exhaust.

I had to read the Wiki on that. In an ideal condition the NOx reaction would release enough O2 to feed the CO reaction. But it's not always idea conditions. Thus the air pipe.

How about if I make it look like it never had the smog pump to start with? And my truck is 25 years old this year. That means to what I understand It doe's not need to be smoged anymore if the car is 25 years old or older.

Some people have an addiction to drink... Some people have an addiction to drugs.... I just have an addiction to 4x4's and their accessories....

It's different in every state.

Can I just say I bought the truck from out of state if they ask where is the smog pump? The truck doe's have new plates. If I did not hate California's smog laws so munch I would not get so munch joy out of fighting there smog laws LOL.

Some people have an addiction to drink... Some people have an addiction to drugs.... I just have an addiction to 4x4's and their accessories....

Yea I was thinking that to.But It says on DMV that if a car is over 25 years or older it doe's not need to be smoged. But and then it says A car made before 1976 doe's not need to be smoged. I do not know what that means. DMV's web site It is telling me 2 thing that are 7 years a part. Can someone please tell me why there is 2 different things they are telling me. Thanks Jamie

If you're in California then you will need all the emission controls installed and functioning. Get the right parts.

KK thanks.