I had some work done on my car by a local shop. They removed the air pump and left the main stock cat. I have had my car back for 4 months. Now it seems like I am going through way to much gas, and my car runs really rich. I drove 25 miles on a 1/4 tank. My cars to stumble when I add boost. Could it be that my main cat is screwed up and clogged. The mods I have are small street port, intake, dp, cb, no airpump and no a/c, stock ecu for now. Any information would be great.

 

yeah, you should take out that main cat and put in a Mid Pipe.
But it sound like a ECU issue. Get a PFC before the Mid Pipe though..

 

Just removing the air pump makes it run super rich at idle and vacuum or cruising. This destroys gas milage. You either have to put the air pump back on or get a different ecu. Also, having a cat in there will cause it to get clogged with unburned fuel. I don't know if a clogged cat will cause your car to stumble, you might have other problems.

 

The "stock cat + no air pump = trouble" equation is a popular rumor, but I doubt it is true. That doesn't mean that your cat isn't clogged, but a clogged cat is not the guaranteed result of removing the air pump.

The gas mileage and stumble might indicate a leaky injector. Do you have problems starting the car when the engine is warm (flooding)?

-Max

 

Dont remove the maincat with out porting your WG, Especialy if you dont have a Aftermarket ECU, other wize you will creep