i have a 91 rs with a tbi 305. im bolting on some headers this winter and i want to pull off the smog pump. i wanted to know if it will screw w/ my ECM. i also wanted to know if there was an intake manifold i could bolt the the stock tbi on that isnt egr and if my car would still run. i appreciate the help guys.. -matt

 

I know with me I am not running a smog pump and no problems at all.

 

wont affect the computer at all, take it out, throw it into a storage area, and take pride in the space you made in your engine bay.

EGR is a different story though.....

Just remember to get a belt thats 2-3 inches longer for when you re-route it after the pump is removed.

 

well what about egr?

 

Keep the egr. Its actually good for mileage. It also saves your o-rings.

 

so i can get away w/ headers w/o the AIR tubes, the egr comes back to the intake thru passages in the heads, am i right?

 

Yes and yes

 

i took everything but the AC off my car and rerouted the serpentine belt the only problem with changed the route of the belt is when the motor is cold everything is turning a little faster so the belt squels a bit but once you drive the car it goes away

 

You might want to heat the area around the torx bit that holds the smog pump on before you attack it. I rounded mine off (I hate torx bits so much) and couldnt even turn the head with a set of vice grips. I dont think my air pump will ever come off now lol.

 

YES!!!!!! Im not the only one!!!!!!!!!! I had to take a offset drill and drill the bolt out, and trim the bracket when that happened to me ... suck horribly

 

damn friend of mine had that happen to him i was lucky on my car it came loose

 

Is it OK to remove the air pump and leave the cat or will that screw up the cat? With LT1s, the air pump is electric and I believe it only runs for a little while when the car is started. Will the cat eventually get hot enough to work without the air pump?

 

I think the air pump is there to cool the cat, isn' it?

and i removed my pump, and my headers have the AIR tubes blocked. runs fine.

 

Actually the air pump is to pre-heat the cat, it helps get the cat up to the correct temp.

your car will work fine without it...I have been running without it for 2 years I have not had a problem with anything

 

How do you figure that everything is turning a little faster now? You still have the same size pulley on the crank and that is the pulley which determines the speed of everything else. The only way something is going to spin faster (without an increase in RPM) is placing a smaller pulley on that one item (the alternator, for example) while keeping the crank pulley the same size.

Picture this... take a bicycle (single speed BMX type bike). The front spocket is a 48 tooth and the rear is an 12 tooth. Now, just for this example, that same bike has a ten-speed type idler on it (you know, that thing in the back that moves the chain to a different size spocket). Ok, remember now.... we have the front spocket, the rear spocket, and the idler. With this setup it takes a 48" chain. With this ratio, with one full revolution of the pedals, the rear tire will turn 4 times... a 1:4 ratio.

Now, the idler we don't need, takes up room and actually does nothing at all (for this application since it's only a single speed bike)! We remove the idler and shorten the chain. That's it. We still have that same 1:4 ratio because we never changed the either of the spockets....

You just removed the AIR pump and got a shorter (or longer) belt. Nothing else changed as far as ratios are concerned.

As for the squeling sound, it sounds like your belt is a little on the loose side and the idler is not applying enough pressure. But none of your accessories are running any faster or slower than what there were before you took off your AIR pump.

Later,
Mike

 

i didnt have any trouble getting my torx bits out. Just unbolt all the brackets and go to advance auto and get a 3/8'' bolts the same lengths and run regular hex bolts.

 

Your car will work fine without the air pump, but it is not there to "preheat" the cat. Air pumps were around years before cats. Airpumps reduce hydrocarbons by introducing O2 into the exhaust as close to the valve as possible, to keep the exhaust gases buring as they go through the exhaust. Without the pump, the gases would stop buring as they ran out of O2 in the exhaust system. By eliminating the pump, you will get better performance, and better gas milage. can' loose!
Tom

 

...thats what I always thought it was for (get the cat quickly up to optimum temp), but if you think about it.....what you put below sorta makes sense.

 

if your worried about the cat just take it out to even better sound, performance and milage then. Once again a win win situation.

 

Can someone please explain the difference between the EGR system and the A.I.R. Pump......I always thought they were the same things???

I'm lost....

 

The EGR is Exhaust Gas Recirculation. It routes exhaust back into the engine for further burning. It reduces emissions and cools the combustion temperatures. There's a computer controlled solenoid that controls when and how much exhaust is allowed into the intake, and the exhaust pressure pushes the fumes into the intake - no mechanical loss, just loss due to reduced oxygen content in the intake charge. On the TPI setup the EGR lives under the plenum (don't know where the TBI version sits). Disabling the EGR will set engine codes since the ECM can and does test to make sure its working.

The air pump (aka smog pump) pumps fresh air into the exhaust system. The pump bolted onto the front of the engine and is belt driven. It pumps air into the exhaust manifold right next to the head and, at least on the TPI setup, directly into the cats. The LT1's went to an electric air pump that doesn't run very much and didn't pump air directly to the cats. It would seem the air pump is more optional than the EGR.

 

So you can remove all the pipes leading to the cat, headers, the black box where they all meet.....the pump on the belt.....and the egr won't be affected??

 

that is correct