I did a LT1 swap into my 91 RS which originally had a 305 TBI. The 305 emissions stuff is long gone. I still have the emissions stuff for the LT1.

I am planning to put the emissions accessories back on the car.

The 305 oem pump had a line going to the cat. The LT1 oem pump is supposed to be plummed to the exhaust manifolds. My headers are not equipped for the AIR tubes, however the cat has a capped-off inlet.

Can I plumb my LT1 AIR pump to the cat rather than the headers like it is designed. I am curious if this would cause any issued or not make a difference.

Thanks in advance for any advice.

 

What year ECM/PCM will it be using? Many of the LT1s had electric AIR pumps that only operate when the engine is warming up. If that is the case, the pump will do you no good without injection fittings on the header tubes. The later cars have no aspirator tube at the converter.

 

1995 computer (The original that came with the engine/smog pump).

I heard that some of the Caprices had problems with the pumps, so the dealers just turned tham off in the computer and the cars still passed emissions. Is this true?

We do not have emission testing of any sort here, but I would rather have the stuff on and working so if we do get it down the road, I dont have to scramble to find all of the parts that will eventually get lost/tossed if not on the car.

 

On the '94-up ECMs and PCMs, the AIR pump only runs until the oxygen sensors are active, then shuts off. There is no port/divert valve. There is no air injection once the engine is warmed, and they pass the sinffer tests easily. The later design cat converters don't need the additional air to complete conversion provided the mixture is maintained correctly. There are typically oxygen sensors installed behind the cats to monitor their effectiveness. If you install the entire 1995 system, everything will be fine,and the system should be cleaner than any 1991 system.

 

Thanks

 

Correct, they are junk. For some reason, being a design flaw or whatnot, they seize up due to water buildup. They only turn on for about 30 seconds when the engine is cold to help warm up the cats faster and then they shut off.

 

When you do get emission testing the emission system will most likely be determined by the car model, or engine whichever is newer.

 

The problem is not with the pump itself, but the moisture admitted from the exhaust stream when one of the AIR check valves begins to fail and leaks backward. The moisture (containing mild acids) has its way with the air pump in short order after that. As long as the air valves are maintained, the pump survives. My '94 has 126K miles on the original air pump, and two new check valves. Still sounds like a canister vacuum every time it starts, for about the first 90 seconds, anyway.

 

Hmm, sounds interesting. My LT1 pump had 134k when it died. Still looks like new. Where are the check valves located exactly?

 

Each exhaust pipe has a 1/4" or so pipe rising to a common 1" manifold pipe, one end of the pipe is closed the other has the check valve on it. There should be a cross-over pipe from the left side check valve to the right side check valve which tee's into the air pump.