Originally Posted by Bones
I thought this was only true if you have an o2 sensor post cat. A lot of early OBD only has a O2 sensor pre cat, so the PCM really isn't monitoring the effectiveness of your cat.
Scooter can correct me if I am wrong
For catalyst efficiency, the only way I've ever seen a MIL associated with it has been as Bones said - need a post - O2 sensor to monitor the exhaust after the cat.
Originally Posted by rverjeeper
I appreciate the feedback guys. One thing I didn't think to mention in my first post is this vehicle does NOT have a catalytic converter, it never did. If there were still leaded gas pumps around, the larger nossle would fit the gas filler tube.
Without the smog pump belt, the pumps just idle, no further modification, the vehicle seem to run fine for a 30 mile each way trip.
With the added information, any wisdom definitely welcome.
Then those pumps feed directly into your exhaust manifolds and could be removed and have the lines capped. When you have pumps and no cat, there is a benefit to plumbing the air into the exhaust right after the valve. At this point, the exhaust is still hot enough to enable the extra oxygen from the pump to burn some of the unburned exhaust gasses right in the cast-iron manifold.